Getty Mark Garlick/Science Photo Library

In the first quarter of the 20th century, it was an intense time to be a physicist. It seemed like every day someone was coming out with a new theory that completely revolutionized our understanding of the universe. In 1905 Einstein published his Theory of Special Relativity, which changed the way physicists thought about space and time. Ten years later, Einstein published his Theory of General Relativity, which was even more revolutionary. OK so it was a lot of Einstein, but still.

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At about the same time, a group of physicists were beginning to study very tiny particles like electrons, as well as the weird things that can happen with light. They began to develop a theory called quantum mechanics, which contains the idea that at the smallest level, measurements of position, momentum, energy, and other quantities are uncertain.

Many physicists spent their entire careers trying to unify these two titans of 20th century physics. In 1928, one man finally succeeded, and in the process, managed to predict the existence of antimatter. As PBS Space Time explains:

Physicists trying to unite relativity and quantum mechanics had a bit of a problem. One of the key ideas of relativity is that time and space are relative, and everything depends on where you are and how fast you're moving. But that idea doesn't show up anywhere in quantum mechanics.

British Physicist Paul Dirac decided to fix this problem by combining Einstein's famous E=mc2 equation with Schroedinger's equation from quantum mechanics. What he got could only be described as an ugly mess. But Dirac saw a way to fix it.

Paul Dirac in 1928.

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However, his solution was a bit strange. In order for the math to work, he needed to add in an extra type of electron, with negative energy. Nobody knew what this was or even what it meant, but it made the end result so simple and elegant that Dirac just knew it was true.

Only a few years later, observations of cosmic rays in the upper atmosphere discovered the first antimatter particles, confirming Dirac's hypothesis. He showed that relativity and quantum mechanics could be combined after all, creating a completely new branch of physics: quantum field theory.

Source: PBS Space Time

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In 1928, One Physicist Accidentally Predicted Antimatter - Popular Mechanics

June 23, 2017 by Carla Reiter Here 3 symbolizes an Efimov molecule comprised of three atoms. While all 3s look about the same, research from the Chin group observed a tiny 3 that is clearly different. Credit: Cheng Chin

New research by physicists at the University of Chicago settles a longstanding disagreement over the formation of exotic quantum particles known as Efimov molecules.

The findings, published last month in Nature Physics, address differences between how theorists say Efimov molecules should form and the way researchers say they did form in experiments. The study found that the simple picture scientists formulated based on almost 10 years of experimentation had it wronga result that has implications for understanding how the first complex molecules formed in the early universe and how complex materials came into being.

Efimov molecules are quantum objects formed by three particles that bind together when two particles are unable to do so. The same three particles can make molecules in an infinite range of sizes, depending on the strength of the interactions between them.

Experiments had shown the size of an Efimov molecule was roughly proportional to the size of the atoms that comprise ita property physicists call universality.

"This hypothesis has been checked and rechecked multiple times in the past 10 years, and almost all the experiments suggested that this is indeed the case," said Cheng Chin, a professor of physics at UChicago, who leads the lab where the new findings were made. "But some theorists say the real world is more complicated than this simple formula. There should be some other factors that will break this universality."

The new findings come down somewhere between the previous experimental findings and predictions of theorists. They contradict both and do away with the idea of universality.

"I have to say that I am surprised," Chin said. "This was an experiment where I did not anticipate the result before we got the data."

The data came from extremely sensitive experiments done with cesium and lithium atoms using techniques devised by Jacob Johansen, previously a graduate student in Chin's lab who is now a postdoctoral fellow at Northwestern University. Krutik Patel, a graduate student at UChicago, and Brian DeSalvo, a postdoctoral researcher at UChicago, also contributed to the work.

"We wanted to be able to say once and for all that if we didn't see any dependence on these other properties, then there's really something seriously wrong with the theory," Johansen said. "If we did see dependence, then we're seeing the breakdown of this universality. It always feels good, as a scientist, to resolve these sorts of questions."

Developing new techniques

Efimov molecules are held together by quantum forces rather than by the chemical bonds that bind together familiar molecules such as H2O. The atoms are so weakly connected that the molecules can't exist under normal conditions. Heat in a room providing enough energy to shatter their bonds.

The Efimov molecule experiments were done at extremely low temperatures50 billionths of a degree above absolute zeroand under the influence of a strong magnetic field, which is used to control the interaction of the atoms. When the field strength is in a particular, narrow range, the interaction between atoms intensifies and molecules form. By analyzing the precise conditions in which formation occurs, scientists can infer the size of the molecules.

But controlling the magnetic field precisely enough to make the measurements Johansen sought is extremely difficult. Even heat generated by the electric current used to create the field was enough to change that field, making it hard to reproduce in experiments. The field could fluctuate at a level of only one part in a milliona thousand times weaker than the Earth's magnetic fieldand Johansen had to stabilize it and monitor how it changed over time.

The key was a technique he developed to probe the field using microwave electronics and the atoms themselves.

"I consider what Jacob did a tour de force," Chin said. "He can control the field with such high accuracy and perform very precise measurements on the size of these Efimov molecules and for the first time the data really confirm that there is a significant deviation of the universality."

The new findings have important implications for understanding the development of complexity in materials. Normal materials have diverse properties, which could not have arisen if their behavior at the quantum level was identical. The three-body Efimov system puts scientists right at the point at which universal behavior disappears.

"Any quantum system made with three or more particles is a very, very difficult problem," Chin said. "Only recently do we really have the capability to test the theory and understand the nature of such molecules. We are making progress toward understanding these small quantum clusters. This will be a building block for understanding more complex material."

Explore further: Exotic, gigantic molecules fit inside each other like Russian nesting dolls

More information: Jacob Johansen et al. Testing universality of Efimov physics across broad and narrow Feshbach resonances, Nature Physics (2017). DOI: 10.1038/nphys4130

University of Chicago scientists have experimentally observed for the first time a phenomenon in ultracold, three-atom molecules predicted by Russian theoretical physicist Vitaly Efimov in 1970.

An exotic physical effect based on the attraction among three particles has a similar universality to that of common two-body interactions, Yusuke Horinouchi from the University of Tokyo and Masahito Ueda from the RIKEN Center ...

An international team of physicists has converted three normal atoms into a special new state of matter whose existence was proposed by Russian scientist Vitaly Efimov in 1970.

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New research by physicists at the University of Chicago settles a longstanding disagreement over the formation of exotic quantum particles known as Efimov molecules.

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Physicists settle debate over how exotic quantum particles form - Phys.Org

June 22, 2017 Artist's rendering of a quantum thermometer. Credit: Emily Edwards/JQI

In an arranged marriage of optics and mechanics, physicists have created microscopic structural beams that have a variety of powerful uses when light strikes them. Able to operate in ordinary, room-temperature environments, yet exploiting some of the deepest principles of quantum physics, these optomechanical systems can act as inherently accurate thermometers, or conversely, as a type of optical shield that diverts heat. The research was performed by a team led by the Joint Quantum Institute (JQI), a research collaboration of the National Institute of Standards and Technology (NIST) and the University of Maryland.

Described in a pair of new papers in Science and Physical Review Letters, the potential applications include chip-based temperature sensors for electronics and biology that would never need to be adjusted since they rely on fundamental constants of nature; tiny refrigerators that can cool state-of-the-art microscope components for higher-quality images; and improved "metamaterials" that could allow researchers to manipulate light and sound in new ways.

Made of silicon nitride, a widely used material in the electronics and photonics industries, the beams are about 20 microns (20 millionths of a meter) in length. They are transparent, with a row of holes drilled through them to enhance their optical and mechanical properties.

"You can send light down this beam because it's a transparent material. You can also send sound waves down the beam," explained Tom Purdy, a NIST physicist who is an author on both papers. The researchers believe the beams could lead to better thermometers, which are now ubiquitous in our devices, including cell phones.

"Essentially we're carrying a bunch of thermometers around with us all the time," said JQI Fellow Jake Taylor, senior author of the new papers. "Some provide temperature readings, and others let you know if your chip is too hot or your battery is too cold. Thermometers also play a crucial role in transportation systemsairplanes, carsand tell you if your engine oil is overheating."

But the problem is that these thermometers are not accurate off the shelf. They need to be calibrated, or adjusted, to some standard. The design of the silicon nitride beam avoids this situation by relying on fundamental physics. To use the beam as a thermometer, researchers must be able to measure the tiniest possible vibrations in the beam. The amount that the beam vibrates is proportional to the temperature of its surroundings.

The vibrations can come from two kinds of sources. The first are ordinary "thermal" sources such as gas molecules buffeting the beam or sound waves passing through it. The second source of vibration comes purely from the world of quantum mechanics, the theory that governs behavior of matter at the atomic scale. The quantum behavior occurs when the researchers send particles of light, or photons, down the beam. Struck by light, the mechanical beam reflects the photons, and recoils in the process, creating small vibrations in the beam. Sometimes these quantum-based effects are described using the Heisenberg uncertainty relationshipthe photon bounce leads to information about the beam's position, but because it imparts vibrations to the beam, it adds uncertainty to the beam's velocity.

"The quantum mechanical fluctuations give us a reference point because essentially, you can't make the system move less than that," Taylor said. By plugging in values of Boltzmann's constant and Planck's constant, the researchers can calculate the temperature. And given that reference point, when the researchers measure more motion in the beam, such as from thermal sources, they can accurately extrapolate the temperature of the environment.

However, the quantum fluctuations are a million times fainter than the thermal vibrations; detecting them is like hearing a pin drop in the middle of a shower.

In their experiments, the researchers used a state-of-the-art silicon nitride beam built by Karen Grutter and Kartik Srinivasan at NIST's Center for Nanoscale Science and Technology. By shining high-quality photons at the beam and analyzing photons emitted from the beam shortly thereafter, "we see a little bit of the quantum vibrational motion picked up in the output of light," Purdy explained. Their measurement approach is sensitive enough to see these quantum effects all the way up to room temperature for the first time, and is published in this week's issue of Science.

Although the experimental thermometers are in a proof-of-concept phase, the researchers envision they could be particularly valuable in electronic devices, as on-chip thermometers that never need calibration, and in biology.

"Biological processes, in general, are very sensitive to temperature, as anyone who has a sick child knows. The difference between 37 and 39 degrees Celsius is pretty large," Taylor said. He foresees applications in biotechnology, when you want to measure temperature changes in "as small an amount of product as possible," he said.

The researchers go in the opposite direction in a second proposed application for the beams, described in a theoretical paper published in Physical Review Letters.

Instead of letting heat hit the beam and allow it to serve as a temperature probe, the researchers propose using the beam to divert the heat from, for example, a sensitive part of an electromechanical device.

In their proposed setup, the researchers enclose the beam in a cavity, a pair of mirrors that bounce light back and forth. They use light to control the vibrations of the beam so that the beam cannot re-radiate incoming heat in its usual direction, towards a colder object.

For this application, Taylor likens the behavior of the beam to a tuning fork. When you hold a tuning fork and strike it, it radiates pure sound tones instead of allowing that motion to turn into heat, which travels down the fork and into your hand.

"A tuning fork rings for a long time, even in air," he said. The two prongs of the fork vibrate in opposite directions, he explained, and cancel out a way for energy to leave the bottom of the fork through your hand.

The researchers even imagine using an optically controlled silicon nitride beam as the tip of an atomic force microscope (AFM), which detects forces on surfaces to build up atom-scale images. An optically controlled AFM tip would stay cooland perform better. "You're removing thermal motion, which makes it easier to see signals," Taylor explained.

This technique also could be put to use to make better metamaterials, complex composite objects that manipulate light or sound in new ways and could be used to make better lenses or even so-called "invisibility cloaks" that cause certain wavelengths of light to pass through an object rather than bouncing from it.

"Metamaterials are our answer to, 'How do we make materials that capture the best properties for light and sound, or for heat and motion?'" Taylor said. "It's a technique that has been widely used in engineering, but combining the light and sound together remains still a bit open on how far we can go with it, and this provides a new tool for exploring that space."

Explore further: Fundamentally accurate quantum thermometer created

More information: "Quantum correlations from a room-temperature optomechanical cavity" Science (2017). science.sciencemag.org/cgi/doi/10.1126/science.aag1407

Xunnong Xu et al. Cooling a Harmonic Oscillator by Optomechanical Modification of Its Bath, Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.118.223602

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Quantum thermometer or optical refrigerator? - Phys.Org

By Ivan Potocki, ContributorPublished: June 22, 2017 07:01 EST

Many of the answers to lifes great questions have been laid at the door of the mega-brained scientists who specialise in quantum physics. Is there evidence of a god? How did the universe begin?

But what about using the theories to revolutionize how we play casinos?

A team of scientists from China and Bristol has come up with the idea of a gambling protocol that doesnt depend on the integrity of the participants. Instead, this new protocol is founded on the idea of rationality the rational notion that both parties will make decisions they perceive give them the best winning chances.

This new protocol is based on the mix of game theory and quantum mechanics, and scientists believe it could find its application in casinos and lotteries sometime in the future.

It is nearly impossible for two players to gamble, putting something of value on the line, without having a third party supervising the game because of the temptation to bend the rules or cheat. This third party is necessary to make sure everything is fair, and everyone keeps their end of the bargain. However, it seems that quantum mechanics has a solution that would remove the need for the third party altogether.

The idea of quantum gambling revolves around the concept of a theoretical machine constructed between two participating players. The machine works based on two important principles: quantum superposition and Heisenbergs uncertainty principle.

The uncertainty principle is a bit hard to understand for people not familiar with quantum mechanics, but it basically states that observing a particle will create changes in its behavior. Quantum superposition means that the particle can be in the two different states at once.

If this sounds confusing, thats because it is.

But, the gist of it all is, it would create a situation where one player knows the state of two particles on his or her side but doesnt know if the states will change by the time they reach the other player. The other player has an option to try and guess the state of the particle hes been sent, or ask for a different one.

In theory, this would create an environment where both players need to adhere to the best strategy, creating Nash equilibrium.

In this situation, they are playing a zero sum game, and there is no need for third parties to supervise the game. Although this idea only exists on paper at this time, scientists believe it can be used to develop a range of new gambling protocols based on quantum mechanics.

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How quantum physics could revolutionize casinos and betting if you can understand it - Casinopedia

Big data is a challenge for all automakers, but especially German companies because they target affluent customers who want the latest technology.

At the same time, the focus on computing pits the automakers against Silicon Valley tech companies with far more experience in the field, and creates an opening for firms like Apple and Google, which are already encroaching on the car business.

Google has long been working on self-driving or autonomous cars, and Tim Cook, the chief executive of Apple, said this month that the company best known for making iPhones is focusing on autonomous systems for cars and other applications.

That has put pressure on automakers. German companies in particular have already made investments in ride-sharing services, in part to combat the rise of Uber, and are now looking further into the future.

Efforts by Volkswagen, trying to remake itself as a technology leader as it recovers from an emissions scandal, show how far into exotic realms of technology carmakers are willing to go.

Volkswagen, a German company, recently joined the handful of large corporations worldwide that are customers of D-Wave Systems, a Canadian maker of computers that apply the mind-bending principles of quantum physics.

While some experts question their usefulness, D-Wave computers housed in tall, matte black cases that recall the obelisks in the science fiction classic 2001: A Space Odyssey can in theory process massive amounts of information at unheard-of speeds. Martin Hofmann, Volkswagens chief information officer, is a believer.

For us, its a new era of technology, Mr. Hofmann said in an interview at Volkswagens vast factory complex in Wolfsburg, Germany.

First theorized in the 1980s, quantum computers seek to harness the strange and counterintuitive world of quantum physics, which studies the behavior of particles at the atomic and subatomic level. While classical computers are based on bits with a value of either 1 or 0, the qubits in a quantum computer can exist in multiple states at the same time. That allows them, in theory, to perform calculations that would be beyond the powers of a typical computer.

This year Volkswagen used a D-Wave computer to demonstrate how it could steer the movements of 10,000 taxis in Beijing at once, optimizing their routes and thereby reducing congestion.

Because traffic patterns morph constantly, the challenge is to gather and analyze vehicle flows quickly enough for the data to be useful. The D-Wave computer was able to process in a few seconds information that would take a conventional supercomputer 30 minutes, said Florian Neukart, a scientist at a Volkswagen lab in San Francisco.

Such claims are met with skepticism by some experts, who say there is no convincing proof that D-Wave computers are faster than a well-programmed conventional supercomputer. And unlike a quantum computer, a supercomputer does not have components that must be kept at temperatures colder than deep space.

If this were an application where D-Wave were actually faster, then it would be the first time wed ever seen that, said Scott Aaronson, a vocal D-Wave skeptic who is a professor of theoretical computer science at the University of Texas at Austin.

It would be particularly astonishing that this milestone should happen first for a Volkswagen application problem, Mr. Aaronson said in an email.

Volkswagen executives say they will publish the results of their work with D-Wave computers, allowing outsiders to try to debunk them.

If the D-Wave collaboration proves to be a misstep for Volkswagen, it would illustrate the hazards of big data for companies whose main focus for the past century has been the internal combustion engine. It also reflects the stakes for one of the worlds biggest carmakers.

Suppliers are also gearing up for an era of automotive big data. Bosch, the electronics maker based in a suburb of Stuttgart, said Monday that it would invest 1 billion euros, or $1.1 billion, to build a new factory in Dresden to produce chips for a variety of applications, including the sensors used in self-driving cars.

Bosch prefers to build its own chips rather than buy them from a supplier, said Christine Haas, director for connected services at the company. When you have done it yourself, then you have a much deeper understanding of the technology, she said.

Some car companies have decided to concentrate on what they do best and let others handle the computing.

Volvo Cars has been a pioneer in marrying digital technology and automobiles. It has turned to outside providers like Ericsson, a Swedish maker of telecommunications equipment, for computer technology. In May, Volvo said it would install Googles Android operating system in new cars beginning in 2019. And the company is cooperating with Uber to develop self-driving cars.

We are trying to embrace it, said Martin Kristensson, senior director for autonomous driving and connectivity strategy at Volvo, of the challenge from Silicon Valley.

But, like Volkswagen, many are trying to develop capabilities in-house. Mr. Stolle of BMW said that the carmaker which hired more information technology specialists last year than mechanical engineers needs huge data-crunching capability.

The company has a fleet of 40 prototype autonomous cars it is testing in cooperation with Intel, a chip maker; Mobileye, an Israeli self-driving technology company; and Delphi, an auto components supplier.

BMW uses artificial intelligence to analyze the enormous amounts of data compiled from test drives, part of a quest to build cars that can learn from experience and eventually drive themselves without human intervention.

After test sessions, hard disks in the cars are physically removed and connected to racks of computers at BMWs research center near Munich. The data collected would fill the equivalent of a stack of DVDs 60 miles high, Mr. Stolle said.

That is much more than could be efficiently transmitted over the internet to remote data storage facilities operated by outside providers in the cloud.

A large part of the data center has to be on premises, Mr. Stolle said. The amount is so huge it doesnt work in the cloud.

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BMW and Volkswagen Try to Beat Apple and Google at Their Own Game - New York Times

Schrdingers Cat

Even if youre not that into heavy science, youre probably familiar with Schrdingers cat, the thought experiment that allows us to consider quantum states in which more than one state is possible at once. The cat is in a box that is closed, and with it is a vial of poison, a hammer that can smash the vial, a geiger counter, and a trace amount of radioactive material. The radioactive material, however, is such asmall amount that the geiger counter has only a 50 percent chance of detecting it. If it does, it will trigger the hammers smashing of the vial, and the cat will die.

We wont know until we open the box if the cat is alive or dead. We just know that each possibility it getting killed or surviving is equally likely. So, until the box is open, the cat exists in a kind of super position both alive and dead. Schrdingers point was that demonstrating its impossibility and silliness. But thanks to quantum physics, we now knowits not that silly and not necessarily impossible.

Speaking of thought experiments used to talk about quantum physics that were devised by people who never even considered quantum physics, lets consider the Zeno effect and the anti-Zeno effect. Zeno of Elea was a philosopher who made it his life mission to prove that everything was B.S., and he did that by devising paradoxes to demonstrate that even things that seem obviously true to us are, in fact, false. One of these is the arrow paradox, from which arises the Zeno effect and its corollary.

The Zeno effect works like this: in order to measure or observe something at aparticular moment,it must be motionless. Say you want to see if an atom has decayed or not. In reality, although there are two possible states, most of the time the chances are not 50/50. Thats because it takes time for something to decay at least a tiny bit of time. Therefore, if you check on the atom quickly and often enough, it wont decay.The corollary anti-Zeno effect is also true. If you delay measurement until the atom is likely to have decayed, then keep this pattern going, you can force the system to decay more rapidly.

Scientists at Washington University in St. Louis wanted to know what happens if you disturb the system again and again, but dont relay any data. In other words, they wanted to see if it is the act of measurement and observation or simply the disturbing influence that causes the Zeno effect. To find out, they experimented with qubits and devised quasimeasurement,in which the atom is disturbed, but no information about it is measured or relayed.

The team found that even quasimeasurements cause the Zeno effect. The quantum environment doesnt need to be connected to the outside environment for the disturbance to achieve the effect. These findingsare interesting because they open up new areas of research into how we might beable to control quantum systems.

Oh, and by the way: no cats, philosophers, or physicists were hurt in the experiments.

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How Schrdinger's Cat Helps Explain the New Findings About the Quantum Zeno Effect - Futurism

June 21, 2017• Physics 10, 68

A team of experimentalists and theorists proposes a scalable protocol for quantum computation based on topological superconductors.

Adapted from T. Karzig et al., Phys. Rev. B (2017)

The Herculean thrust to realize a quantum computer by many research groups around the world is, in my opinion, one of the most exciting endeavors in physics in quite some time. Notwithstanding the potential applications that have motivated many companies in this endeavor, a quantum computer represents the most promising avenue to peer into quantum phenomena on a macroscopic scale. As with any such great effort, the race to build a quantum computer has many competitors pursuing a variety of approaches, some of which appear to be on the verge of creating a small machine [1]. However, such small machines are unlikely to uncover truly macroscopic quantum phenomena, which have no classical analogs. This will likely require a scalable approach to quantum computation. A new study by Torsten Karzig from Microsoft Station Q, California, and colleagues [2] brings together the expertise of a large and diverse group of physicists, ranging from experimentalists to topologists, to lay out a roadmap for a scalable architecture based on one of the most popular approaches.

Karzig and colleagues paper represents a vision for the future of a sequence of developments that started with the seminal ideas of topological quantum computation (TQC) as envisioned by Alexei Kitaev [3] and Michael Freedman [4] in the early 2000s. The central idea of TQC is to encode qubits into states of topological phases of matter (see Collection on Topological Phases). Qubits encoded in such states are expected to be topologically protected, or robust, against the prying eyes of the environment, which are believed to be the bane of conventional quantum computation. This is because states of topological phases are locally indistinguishable from each other, so that qubits encoded in such states can evade the destructive coupling to the environment. But experimentally accessible topological phases of matter with the requisite properties for TQC, such as the ability to host quasiparticles known as Majorana zero modes, have been elusive. A milestone in this direction was reached in 2010, when researchers realized [57] that the combination of rather conventional ingredients, such as special semiconductors, superconductors, and magnetic fields, could result in one such phasea topological superconductor. This realization motivated experimentalists to discover signatures of this topological phase just a few years after its prediction [8]. However, the topological superconductors, or Majorana nanowires as they are often called, made in these first experiments were plagued by device imperfections such as impurities [8]. While topological robustness is supposed to protect devices from small imperfections, it is sometimes overlooked that the strength of such imperfections must be below a pretty low threshold for topological robustness to be operative.

A new wave of optimism swept the search for TQC-ready topological superconductors in 2016. Thats when experimental groups from the University of Copenhagen and from the Delft University of Technology, led by Charlie Marcus and Leo Kouwenhoven, respectively, demonstrated high-quality Majorana nanowires that were likely to be in the topological regime [9, 10]. These devices, fabricated through epitaxial growth of superconducting aluminum on indium antimonide semiconductors, showed evidence of a high-quality superconducting gap [10] and also of near energy degeneracy between the topological qubit states [9]; a large energy difference between qubit states is often related to the detrimental decoherence rate of a qubit. However, the rules of the game of designing and fabricating Majorana nanowire devices have proven to be rather different from what had been anticipated. For example, it turns out that it is quite straightforward to drive the newly fabricated devices [9] into the desirable Coulomb blockade regime (where the quantization of electronic charge dominates charge transport) but difficult to fabricate controllable contacts to connect the devices to superconducting circuitry. Interestingly, concurrent theoretical work has clarified that the topological qubit state of a Majorana nanowire can be measured via the phase shift of electron transport through the device when the transport is in the Coulomb blockade regime. This work led to suggestions that the basic operations for TQC could be performed using a procedure that relied on measurements of topological qubits.

Karzig and colleagues study comes at a point in time where there is optimism for the realization of TQC using Majorana nanowires but possibly along a path with several constraints. For example, branched structures of a nanowire could be used to generate a network of wires for TQC, but superconducting contacts are only easy to make at the ends of the wire. This would mean that superconducting contacts must be avoided in making a large network of wires. Also, the qubit lifetime will ultimately likely be limited by quasiparticle poisoning, a phenomenon in which an anomalously large number of unwanted quasiparticles, arising from Cooper electron pairs broken by stray microwaves, exists in the devices. The Karzig study brings together a large number of authors with expertise in device fabrication, in strategies for TQC, and in the solid-state-physics issues involving Majorana nanowires. The researchers propose a protocol for scalable TQC based on the existing Majorana nanowires, assuming that they can be brought into the topological phase.

The protocol involves designing a network from small sets of Majorana wires and performing a sequence of measurements on the sets (Fig. 1). The central idea is to use physical constraints on the network, such as aligning all wires with a global magnetic field, to predict which sets may be measured easily to perform TQC. For example, the researchers considered networks made from sets of four and six wires (tetron and hexon designs) together with the rule that only nearby Majorana zero modes could be measured in each configuration. They then devised a strategy for TQC that optimizes robustness to quantities such as environmental temperature and noise as well the size of the network. The result of the analysis is a few scalable architectures that future experimental groups could pick between, depending on their device-construction capabilities and computational goals. The hexon architectures are likely to be computationally more efficient than the tetron architectures but will probably be more difficult to construct.

While the scope of this work might be limited to these specific devices, detailed analysis of this kind is absolutely key to motivating both experimentalists and theorists to make progress towards a realistic platform for TQC that actually works in practice. The Karzig study likely lays the foundation for analogous work with other topological platforms as they become experimentally viable candidates for TQC. I must also clarify that the significance of this work does depend on whether future experiments meet the outstanding experimental challenges, foremost among which is the reliable generation of Majorana nanowires in a topological phase. That being said, I think Karzig and co-workers paper will serve as a case study to follow, even if the properties of topological superconducting systems turn out to be somewhat different from the ones assumed.

This research is published in Physical Review B.

Jay Sau is an Assistant Professor of Physics at the University of Maryland (UMD), College Park. He holds a B.Tech. in electrical engineering from the Indian Institute of Technology (IIT) in Kanpur, India, and a Ph.D. in physics from the University of California at Berkeley. After postdoctoral positions at UMD and Harvard University, he joined the Physics Department at UMD in 2013. His research group develops theoretical tools in condensed-matter physics to predict and understand topological phases that might one day be used to perform topological quantum computation.

Torsten Karzig, Christina Knapp, Roman M. Lutchyn, Parsa Bonderson, Matthew B. Hastings, Chetan Nayak, Jason Alicea, Karsten Flensberg, Stephan Plugge, Yuval Oreg, Charles M. Marcus, and Michael H. Freedman

Phys. Rev. B 95, 235305 (2017)

Published June 21, 2017

Torsten Karzig, Christina Knapp, Roman M. Lutchyn, Parsa Bonderson, Matthew B. Hastings, Chetan Nayak, Jason Alicea, Karsten Flensberg, Stephan Plugge, Yuval Oreg, Charles M. Marcus, and Michael H. Freedman

Phys. Rev. B 95, 235305 (2017)

Published June 21, 2017

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Viewpoint: A Roadmap for a Scalable Topological Quantum Computer - Physics

In Brief Chinese physicists managed to demonstrate long-distance quantum entanglement in space, breaking previous records. This development, made possible by a novel method, could lead to improved information storage and transfer in the future. Spooky Action Gets to Space

When it comes to weird science stuff, quantum entanglement is probably nearthe top of the list, especially back in the days when Einstein referred to it as that spooky action at a distance. Physicists have since demonstrated the spookyphenomenon to be possible, but now theywant to extend itsreach. A new study shows its possible for quantum entanglement to spanfar longer distances than previously demonstrated.

We have demonstrated the distribution of two entangled photons from a satellite to two ground stations that are 1,203 kilometers [748 miles] apart, lead author Juan Yin, physicist at the Science and Technology University of China in Shanghai, explained in aresearch paper published in the journal Science. The previous record for entanglement distribution reached only 100 kilometers (62 miles).

Yins team used the Micius, the worlds first quantum-enabled satellite which China launched in 2016, to transmit entangled photons to several ground stations separated by long distances. They managed to achieve this feat by using laser beams to prevent the light particles from gettinglost as they traveled.

The result again confirms the nonlocal feature of entanglement and excludes the models of reality that rest on the notions of locality and realism, Yin and his colleagues wrote.

Though quantum entanglement is incredibly complex, its possible to explain itin simple terms. Two or more particles are entangled or linked when a change in ones state or properties instantaneously affects the others. What makes this stranger is that this link works regardless of distance. This phenomenon becomes particularly useful in storing information as in the case of using quantum bits (qubits) in quantum computing.

By proving that quantum entanglement can be maintained in space over such a long distance, this work paves the way for long-distance satellite quantum communication and maybe even realize the possibilities for quantum teleportation. Long-distance entanglement distribution is essential for the testing of quantum physics and quantum networks, Yins team wrote.

Advances in quantum cryptography, which rely heavily on extending entanglement, could change the way information is stored and transferred in the future opening up applications in improved security in communication and even payment systems.

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Physicists Demonstrate Record Breaking Long-Distance Quantum Entanglement in Space - Futurism

Quantum mechanics is the body of scientific laws that describe the wacky behavior of photons, electrons and the other particles that make up the universe.

Quantum mechanics is the branch of physics relating to the very small.

It results in what may appear to be some very strange conclusions about the physical world. At the scale of atoms and electrons, many of the equations ofclassical mechanics, which describe how things move at everyday sizes and speeds, cease to be useful. In classical mechanics, objects exist in a specific place at a specific time. However, in quantum mechanics, objects instead exist in a haze of probability; they have a certain chance of being at point A, another chance of being at point B and so on.

Quantum mechanics (QM) developed over many decades, beginning as a set of controversial mathematical explanations of experiments that the math of classical mechanics could not explain. It began at the turn of the 20th century, around the same time that Albert Einstein published histheory of relativity, a separate mathematical revolution in physics that describes the motion of things at high speeds. Unlike relativity, however, the origins of QM cannot be attributed to any one scientist. Rather, multiple scientists contributed to a foundation of three revolutionary principles that gradually gained acceptance and experimental verification between 1900 and 1930. They are:

Quantized properties: Certain properties, such as position, speed and color, can sometimes only occur in specific, set amounts, much like a dial that "clicks" from number to number. This challenged a fundamental assumption of classical mechanics, which said that such properties should exist on a smooth, continuous spectrum. To describe the idea that some properties "clicked" like a dial with specific settings, scientists coined the word "quantized."

Particles of light: Light can sometimes behave as a particle. This was initially met with harsh criticism, as it ran contrary to 200 years of experiments showing that light behaved as a wave; much like ripples on the surface of a calm lake. Light behaves similarly in that it bounces off walls and bends around corners, and that the crests and troughs of the wave can add up or cancel out. Added wave crests result in brighter light, while waves that cancel out produce darkness. A light source can be thought of as a ball on a stick beingrhythmically dipped in the center of a lake. The color emitted corresponds to the distance between the crests, which is determined by the speed of the ball's rhythm.

Waves of matter: Matter can also behave as a wave. This ran counter to the roughly 30 years of experiments showing that matter (such as electrons) exists as particles.

In 1900, German physicist Max Planck sought to explain the distribution of colors emitted over the spectrum in the glow of red-hot and white-hot objects, such as light-bulb filaments. When making physical sense of the equation he had derived to describe this distribution, Planck realized it implied that combinations of only certaincolors(albeit a great number of them) were emitted, specifically those that were whole-number multiples of some base value. Somehow, colors were quantized! This was unexpected because light was understood to act as a wave, meaning that values of color should be a continuous spectrum. What could be forbiddingatomsfrom producing the colors between these whole-number multiples? This seemed so strange that Planck regarded quantization as nothing more than a mathematical trick. According to Helge Kragh in his 2000 article in Physics World magazine, "Max Planck, the Reluctant Revolutionary," "If a revolution occurred in physics in December 1900, nobody seemed to notice it. Planck was no exception "

Planck's equation also contained a number that would later become very important to future development of QM; today, it's known as "Planck's Constant."

Quantization helped to explain other mysteries of physics. In 1907, Einstein used Planck's hypothesis of quantization to explain why the temperature of a solid changed by different amounts if you put the same amount of heat into the material but changed the starting temperature.

Since the early 1800s, the science ofspectroscopyhad shown that different elements emit and absorb specific colors of light called "spectral lines." Though spectroscopy was a reliable method for determining the elements contained in objects such as distant stars, scientists were puzzled aboutwhyeach element gave off those specific lines in the first place. In 1888, Johannes Rydberg derived an equation that described the spectral lines emitted by hydrogen, though nobody could explain why the equation worked. This changed in 1913 whenNiels Bohrapplied Planck's hypothesis of quantization to Ernest Rutherford's 1911 "planetary" model of the atom, which postulated that electrons orbited the nucleus the same way that planets orbit the sun. According toPhysics 2000(a site from the University of Colorado), Bohr proposed that electrons were restricted to "special" orbits around an atom's nucleus. They could "jump" between special orbits, and the energy produced by the jump caused specific colors of light, observed as spectral lines. Though quantized properties were invented as but a mere mathematical trick, they explained so much that they became the founding principle of QM.

In 1905, Einstein published a paper, "Concerning an Heuristic Point of View Toward the Emission and Transformation of Light," in which he envisioned light traveling not as a wave, but as some manner of "energy quanta." This packet of energy, Einstein suggested, could "be absorbed or generated only as a whole," specifically when an atom "jumps" between quantized vibration rates. This would also apply, as would be shown a few years later, when an electron "jumps" between quantized orbits. Under this model, Einstein's "energy quanta" contained the energy difference of the jump; when divided by Plancks constant, that energy difference determined the color of light carried by those quanta.

With this new way to envision light, Einstein offered insights into the behavior of nine different phenomena, including the specific colors that Planck described being emitted from a light-bulb filament. It also explained how certain colors of light could eject electrons off metal surfaces, a phenomenon known as the "photoelectric effect." However, Einstein wasn't wholly justified in taking this leap, said Stephen Klassen, an associate professor of physics at the University of Winnipeg. In a 2008 paper, "The Photoelectric Effect: Rehabilitating the Story for the Physics Classroom," Klassen states that Einstein's energy quanta aren't necessary for explaining all of those nine phenomena. Certain mathematical treatments of light as a wave are still capable of describing both the specific colors that Planck described being emitted from a light-bulb filament and the photoelectric effect. Indeed, in Einstein's controversial winning of the 1921Nobel Prize, the Nobel committee only acknowledged "his discovery of the law of the photoelectric effect," which specifically did not rely on the notion of energy quanta.

Roughly two decades after Einstein's paper, the term "photon" was popularized for describing energy quanta, thanks to the 1923 work of Arthur Compton, who showed that light scattered by an electron beam changed in color. This showed that particles of light (photons) were indeed colliding with particles of matter (electrons), thus confirming Einstein's hypothesis. By now, it was clear that light could behave both as a wave and a particle, placing light's "wave-particle duality" into the foundation of QM.

Since the discovery of the electron in 1896, evidence that all matter existed in the form of particles was slowly building. Still, the demonstration of light's wave-particle duality made scientists question whether matter was limited to actingonlyas particles. Perhaps wave-particle duality could ring true for matter as well? The first scientist to make substantial headway with this reasoning was a French physicist named Louis de Broglie. In 1924, de Broglie used the equations of Einstein'stheory of special relativityto show that particles can exhibit wave-like characteristics, and that waves can exhibit particle-like characteristics. Then in 1925, two scientists, working independently and using separate lines of mathematical thinking, applied de Broglie's reasoning to explain how electrons whizzed around in atoms (a phenomenon that was unexplainable using the equations ofclassical mechanics). In Germany, physicist Werner Heisenberg (teaming with Max Born and Pascual Jordan) accomplished this by developing "matrix mechanics." Austrian physicist ErwinSchrdingerdeveloped a similar theory called "wave mechanics." Schrdinger showed in 1926 that these two approaches were equivalent (though Swiss physicist Wolfgang Pauli sent anunpublished resultto Jordan showing that matrix mechanics was more complete).

The Heisenberg-Schrdinger model of the atom, in which each electron acts as a wave (sometimes referred to as a "cloud") around the nucleus of an atom replaced the Rutherford-Bohr model. One stipulation of the new model was that the ends of the wave that forms an electron must meet. In "Quantum Mechanics in Chemistry, 3rd Ed." (W.A. Benjamin, 1981), Melvin Hanna writes, "The imposition of the boundary conditions has restricted the energy to discrete values." A consequence of this stipulation is that only whole numbers of crests and troughs are allowed, which explains why some properties are quantized. In the Heisenberg-Schrdinger model of the atom, electrons obey a "wave function" and occupy "orbitals" rather than orbits. Unlike the circular orbits of the Rutherford-Bohr model, atomic orbitals have a variety of shapes ranging from spheres to dumbbells to daisies.

In 1927, Walter Heitler and Fritz London further developed wave mechanics to show how atomic orbitals could combine to form molecular orbitals, effectively showing why atoms bond to one another to formmolecules. This was yet another problem that had been unsolvable using the math of classical mechanics. These insights gave rise to the field of "quantum chemistry."

Also in 1927, Heisenberg made another major contribution to quantum physics. He reasoned that since matter acts as waves, some properties, such as an electron's position and speed, are "complementary," meaning there's a limit (related to Planck's constant) to how well the precision of each property can be known. Under what would come to be called "Heisenberg'suncertainty principle," it was reasoned that the more precisely an electron's position is known, the less precisely its speed can be known, and vice versa. This uncertainty principle applies to everyday-size objects as well, but is not noticeable because the lack of precision is extraordinarily tiny. According to Dave Slaven of Morningside College (Sioux City, IA), if a baseball's speed is known to within aprecision of 0.1 mph, the maximum precision to which it is possible to know the ball's position is 0.000000000000000000000000000008 millimeters.

The principles of quantization, wave-particle duality and the uncertainty principle ushered in a new era for QM. In 1927, Paul Dirac applied a quantum understanding of electric and magnetic fields to give rise to the study of "quantum field theory" (QFT), which treated particles (such as photons and electrons) as excited states of an underlying physical field. Work in QFT continued for a decade until scientists hit a roadblock: Many equations in QFT stopped making physical sense because they produced results of infinity. After a decade of stagnation, Hans Bethe made a breakthrough in 1947 using a technique called "renormalization." Here, Bethe realized that all infinite results related to two phenomena (specifically "electron self-energy" and "vacuum polarization") such that the observed values of electron mass and electron charge could be used to make all the infinities disappear.

Since the breakthrough of renormalization, QFT has served as the foundation for developing quantum theories about the four fundamental forces of nature: 1) electromagnetism, 2) the weak nuclear force, 3) the strong nuclear force and 4) gravity. The first insight provided by QFT was a quantum description of electromagnetism through "quantum electrodynamics" (QED), which made strides in the late 1940s and early 1950s. Next was a quantum description of the weak nuclear force, which was unified with electromagnetism to build "electroweak theory" (EWT) throughout the 1960s. Finally came a quantum treatment of the strong nuclear force using "quantum chromodynamics" (QCD) in the 1960s and 1970s. The theories of QED, EWT and QCD together form the basis of theStandard Modelof particle physics. Unfortunately, QFT has yet to produce a quantum theory of gravity. That quest continues today in the studies of string theory and loop quantum gravity.

Robert Coolman is a graduate researcher at the University of Wisconsin-Madison, finishing up his Ph.D. in chemical engineering. He writes about math, science and how they interact with history. Follow Robert@PrimeViridian. Followus@LiveScience,Facebook&Google+.

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What Is Quantum Mechanics? - livescience.com

The Hindu

A quantum step to a great wall for encryption The Hindu Quantum mechanics (QM) is the dark arts of physics. Though physics in the Newtonian mould tells us how every object will precisely behave when pushed and hurled, QM deals with the invisible world of subatomic particles, where counter-intuitive ... New Quantum-Entanglement Record Could Spur Hack-Proof CommunicationsYahoo News Scientists Make Quantum Leap Toward Secure Quantum InternetNewsFactor Network 'Hack-proof' quantum internet networks closer to reality, studies sayCBC.ca Newburgh Gazette -Chicago Tribune -The Monitor Daily all 14 news articles »

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A quantum step to a great wall for encryption - The Hindu

Quantum physics is an often mind-boggling branch of science filled with strange behavior and bizarre implications. For many people, the mere mention of the term is enough to send us hurtling in the opposite direction, like an electron bouncing off the center of an atom.

But evidence is mounting that the future of technology lies in quantum mechanics, which focuses on how the smallest things in our universe work. And a new breakthrough by scientists in China has just brought the world one very big step closer to this quantum revolution. Hundreds of miles closer, in fact. So its as good a time as any to understand why quantum physics is making such waves.

An Atlas 5 rocket, a national security satellite, launched from California in 2008. Chinese physicists have used a satellite to beat the distance record for quantum entanglement. Gene Blevins/Reuters

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Quantum physics is all about waves. And particles. Together. Sort of.

Mostly, we think of light as something that occurs in waves and matter as distinct particles. But theorist Max Plancks attempt in 1900 to explain observations about colors emitted from hot objects started scientists down a path that transformed our understanding of how life works at the very smallest scale.

The first step was realizing that light behaves like a stream of individual particles, called photons. Albert Einstein came to this conclusion following Plancks work. Each photon contains a discrete amount of energy.

Subsequent research by Niels Bohr and others disrupted what physicists understood about electrons, the negatively charged particles that swirl around the heavy centers of the atoms that make up the elements (gold, silver, potassium, calcium, etc.) that in turn make up matter. That disruption was accentuated by Louis de Broglie, who realized that if light can behave like a particle, then maybe electrons, which physicists had always thought of as particles, could behave like waves. Numerous experiments proved that to be the case. Photons behave like waves and particles. Electrons behavelike waves and particles. The type of measurement you do determines how a photon or an electron behave.

One of the most intriguing effects of quantum physics is something called entanglement. With quantum entanglement, two particles derived from the same source behave the same way, even when they are far apart. The state of either particle cannot be determined until it is measured, and the act of measuring is what determines its state. And the measurement of one particle affects the measurement of the other particle. This thinking is embodied by Erwin Schrdingers thought problem about his famous cat.

If you split photon A into a photon pairB and Cmeasuring B will tell you, with absolute certainty, the measure of C. Paul Kwiat, physicist at the University of Illinois, gives the analogy of flipping a coin. If one flipped coin results in heads, heads, tails, heads, tails, tails, head, then the entangled coin, placed hundreds of miles away, would follow the same sequence. Thats not a behavior you see with coins, says Kwiat. Thats where quantum entanglement is pretty weird. Two things hundreds of miles away behaving as one: Thats quantum entanglement. And its real. Albert Einstein called it spuckhafte ferwirklung, or spooky action at a distance.

For more on the history of quantum physics and the entanglement phenomenon, author Chad Orzel, who teaches physics at Union College in Schenectady, New York, has some excellent videos.

Beyond the weirdness factor, quantum entanglement has broad implications for computing and information sharing. Entanglement distributionfor example, the splitting of a single photon into two linked photonscould be used to create a secure internet connection. The technology, called quantum cryptography, would allow the users to detect any eavesdropper on the channel. The reason you can detect the eavesdropper is that such an intruder would necessarily alter the entangled photons by his or her presence.

The principle allows for a secure communication channel that is unhackable, says Jonathan Dowling, a physicist at Louisiana State University When the Chinese roll out this type of communications nationwide, which is their plan, says Dowling, then no matter how many NSA computers you string together, you are never going to be able to tap into their system.

A new study in Science, by Juan Yin and colleagues at the University of Science and Technology in China and several other institutions there, has brought this future technology within much closer reach. The researchers split a photon on a satellite and sent the two resulting photons in two different directions, aimed at ground stations in China. The ground stations were more than 700 miles apart from one another. The distance from the satellite, which was constantly in motion, to each ground station varied from 300 to 1,200 miles.

The researchers managed to send photon pairs to different ground stations repeatedly and confirmed that the photons were entangled. Using a laser pointer-like source, they made about 6 million photon pairs per second. About one pair per second reached the ground stations. Kwiat says its like throwing a dime into a toll booth bucket while driving at high speed, only youre throwing a much tinier object from much farther awayand at a much faster speed. Measurements confirmed that the photon pairs had the same polarization, proving that they were entangled.

Although previous studies have managed to achieve similar results, never has it been done over such a great distance and from a satellite. (The prior record demonstrated entanglement across two of the Canary Islands, about 89 miles apart.) Its a beautiful experiment, says Kwiat. They demonstrated the persistence of entanglement over a longer distance than any experiment before by roughly a factor of 10.

Dowling says that this achievement proves that the quantum-based technologies many physicists envision are attainable. The long-term goal is to build a quantum internet where future computers around the globe are linked together in an uncrackable network of extraordinary computational power, says Dowling. The satellite will go down in history as the first link in the quantum internet.

The Chinese physicists are not the only team on the quest for this technology. Quantum cryptography systems are commercially available and researchers in several countries, including the U.S., Canada, Italy and Singapore are also forging the way ahead, says Kwiat, who is among them. Google is also working on quantum information science.

Still, the new study is a huge breakthrough because it proves entanglement can be achieved from a satellite and across this large distance. We have done something that was absolutely impossible without the satellite, says senior author Jian-Wei Pan. The next step, he says, is to perform more experiments with light from space, across yet longer distances and at faster speeds, with a goal of controlling quantum states and understanding how gravity affects quantum behavior.

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Cybersecurity Attacks Are a Global Threat. Chinese Scientists Have the Answer: Quantum Mechanics - Newsweek

Om-nipotent, Om-nipresent, Om-niscient, Om all is wholly undivided, instructed the physicist, David Bohm the enfolded and unfolded, that of formlessness and form from the implicate unmanifest to the explicate manifest born originating from an underlying nonphysical order emerges physical reality with its illusory borders the whole of existence exists in every wee part all is here nowthe cosmos' stern, bow, starboard and port the invisible portion of existence is pure potentiality awareness itself as a field of infinite possibility physical reality a holographic illusion science says sothat's its conclusion the new science is within and is up to you a simple experiment with loving prayer will do following science honestly, one is led inward too with zero biases, mind and reality are seen as not-two who cares what proofs others are uttering live it yourself or you know nothing make a cloud square shape in a oneness experiment repeat thank you square cloud with joyous, grateful intent the results of this being easily duplicatable shows that a unitive conscious universe is no fable Native Americans have their time-tested rain dance a prayer to the Great Spirit resulting in watered plants Jarett Sabirsh, Love All-Knowing: An Epic Spiritual Poem

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Popular Quantum Physics Books - Goodreads

Chinese scientists have just set a record in quantum physics.

For the first time, pairs of entangled photons have been beamed from a satellite in orbit to two receiving stations almost 1,500 miles away on on Earth.

At the same time, the researchers were able to deliberately separate the entangled photon pairs along a greater distance than has ever been recorded.

The experiment, described Thursday in the journal Science, represents the first measurable proof of an idea that has long been theorized but never tested, experts said.

This is the first time you have a quantum channel between a satellite and the ground that you can actually use, said Norbert Ltkenhaus, a professor at the Institute for Quantum Computing at the University of Waterloo in Canada who was not involved in the new work. People have been talking about doing it for many, many years, but these guys actually did it.

Keep reading to learn what this new work means, and why it matters.

Great question. For starters, a photon is a tiny particle of light. In fact, it's the smallest unit that light can be broken into. It has no mass and no charge.

Entangled photons are a pair of photons whose properties are linked, and remain that way no matter how far apart they get.

If you make a measurement on one of the photons, you get a perfectly correlated outcome on the other member of the pair, Ltkenhaus said.

And that will hold true not matter how many times you look at them.

One measurement alone doesnt tell you they are entangled, you need to repeat it many times, he said. With entangled photons no matter what you measure, or how many times you measure, or which side of the pair you measure, you always get perfect correlation.

Another great question. This one is more difficult to answer.

Scientists have not been able to explain why entanglement occurs. All they know is that it exists.

Einstein referred to the phenomena of entanglement as spooky action at a distance. Others have said it is kind of like the physics version of voodoo.

They built a special satellite to do it.

The spacecraft, nicknamed Micius after a famous 5th century Chinese scientist, launched in August 2016.

It is loaded with a special crystal that can split a single incoming photon into two daughter photons with joint properties. For this experiment, instruments on the satellite separated the entangled photons and sent them to different receiving stations on Earth.

To do this, Micius had to aim at its targets with an amazing degree of precision, said Jian-Wei Pan, a physicist at the University of Science and Technology of China who led the work.

Its the equivalent of clearly seeing a human hair at a distance of 900 feet away, he said.

It is extreme. And, experts say, challenging.

Designing, launching and operating a satellite with this capability is no easy feat, Ltkenhaus said. I see this as a great engineering triumph.

But, as the study demonstrates, using a satellite to send beams of entangled photons to Earth is a better strategy than using optical fibers to distribute them.

The greatest distance scientists have been able to separate entangled photons using optical fibers is 62 miles. By sending the entangled photons through space, Pan and his team were able to separate entangled photons by more than 620 miles.

Not immediately, but eventually, it probably will.

For example, distributing entangled photons over large distances could be used to establish unhackable communications via whats known as quantum cryptography.

This application relies on another strange aspect of quantum mechanics namely that the simple act of observing a photon disturbs it and causes it to change its orientation.

Scientists have already been able to establish secure, quantum channels using fiber optics, but there is a limit to how far those can stretch.

Using the space-based quantum channel, the authors have shown it is possible to significantly extend the distance over which one can perform such a secure communication, said Jrgen Volz, a physicist at the Vienna Center for Quantum Science and Technology who was not involved in the work.

In the time of the Internet, when more and more sensitive information is shared and exchanged via the web, this is of tremendous importance, he said.

But experts say an application like that may still be 10 years away.

Although the experiment was successful, the rate of sending and receiving entangled photons described in the paper was still quite low. Of nearly 6 million entangled photon pairs generated by Micius each second, only one pair was detected at stations here on Earth.

The communication rates here are not yet sufficient for a practical application, said Wenjamin Rosenfeld, a physicist at the Ludwig-Maximilians University in Munich.

However, he added that the mission represents a proof-of-principle demonstration of a quantum communication protocol that could be available in the near future.

Pan put it this way: This is the first baby step for quantum entanglement experiments going into space. It is really new!

deborah.netburn@latimes.com

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Chinese satellite breaks a quantum physics record, beams entangled photons from space to Earth - Los Angeles Times

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Quantum Physics News - Phys.org - News and Articles on ...

Its a sunny Tuesdaymorning in late March at IBMs Thomas J. Watson Research Center. The corridor from the reception area follows the long, curving glass curtain-wall that looks out over the visitors parking lot to leafless trees covering a distant hill in Yorktown Heights, N.Y., an hour north of Manhattan. Walk past the podium from the Jeopardy! episodes at which IBMs Watson smote the human champion of the TV quiz show, turn right into a hallway, and youll enter a windowless lab where a quantum computer is chirping away.

Actually, chirp isnt quite the right word. Its a somewhat metallic sound, chush chush chush, thats made by the equipment that lowers the temperature inside a so-called dilution refrigerator to within hailing distance of absolute zero. Encapsulated in a white canister suspended from a frame, the dilution refrigerator cools a superconducting chip studded with a handful of quantum bits, or qubits.

When it's running, this dilution refrigerator at IBMs Thomas J. Watson Research Center is one of the coldest places in the universe. To cool superconducting bits on a quantum computer processor, it gets down to 15 millikelvin (-459F)colder than outer space.

Photographer: Christopher Payne for Bloomberg Markets

Quantum computing has been around, in theory if not in practice, for several decades. But these new types of machines, designed to harness quantum mechanics and potentially process unimaginable amounts of data, are certifiably a big deal. I would argue that a working quantum computer is perhaps the most sophisticated technology that humans have ever built, says Chad Rigetti, founder and chief executive officer of Rigetti Computing, a startup in Berkeley, Calif. Quantum computers, he says, harness nature at a level we became aware of only about 100 years agoone that isnt apparent to us in everyday life.

Whats more, the potential of quantum computing is enormous. Tapping into the weird way nature works could potentially speed up computing so some problems that are now intractable to classical computers could finally yield solutions. And maybe not just for chemistry and materials science. With practical breakthroughs in speed on the horizon, Wall Streets antennae are twitching.

The second investment that CME Group Inc.s venture arm ever made was in 1QB Information Technologies Inc., a quantum-computing software company in Vancouver. From the start at CME Ventures, weve been looking further ahead at transformational innovations and technologies that we think could have an impact on the financial-services industry in the future, says Rumi Morales, head of CME Ventures LLC.

That 1QBit financing round, in 2015, was led by Royal Bank of Scotland. Kevin Hanley, RBSs director of innovation, says quantum computing is likely to have the biggest impact on industries that are data-rich and time-sensitive. We think financial services is kind of in the cross hairs of that profile, he says.

Goldman Sachs Group Inc. is an investor in D-Wave Systems Inc., another quantum player, as is In-Q-Tel, the CIA-backed venture capital company, says Vern Brownell, CEO of D-Wave. The Burnaby, B.C.-based company makes machines that do something called quantum annealing. Quantum annealing is basically using the quantum computer to solve optimization problems at the lowest level, Brownell says. Weve taken a slightly different approach where were actually trying to engage with customers, make our computers more and more powerful, and provide this advantage to them in the form of a programmable, usable computer.

Marcos Lpez de Prado, a senior managing director at Guggenheim Partners LLC whos also a scientific adviser at 1QBit and a research fellow at the U.S. Department of Energys Lawrence Berkeley National Laboratory, says its all about context. The reason quantum computing is so exciting is its perfect marriage with machine learning, he says. I would go as far as to say that currently this is the main application for quantum computing.

Photographer: Christopher Payne for Bloomberg Markets

Part of that simply derives from the idea of a quantum computer: harnessing a physical device to find an answer, Lpez de Prado says. He sometimes explains it by pointing to the video game Angry Birds. When you play it on your iPad, the central processing units use some mathematical equations that have been programmed into a library to simulate the effects of gravity and the interaction of objects bouncing and colliding. This is how digital computers work, he says.

By contrast, quantum computers turn that approach on its head, Lpez de Prado says. The paradigm for quantum computers is this: Lets throw some birds and see what happens. Encode into the quantum microchip this problem: These are your birds and where you throw them from, so whats the optimal trajectory? Then you let the computer check all possible solutions essentiallyor a very large combination of themand come back with an answer, he says. In a quantum computer, theres no mathematician cracking the problem, he says. The laws of physics crack the problem for you.

The fundamental building blocksof our world are quantum mechanical. If you look at a molecule, says Dario Gil, vice president for science and solutions at IBM Research, the reason molecules form and are stable is because of the interactions of these electron orbitals. Each calculation in thereeach orbitalis a quantum mechanical calculation. The number of those calculations, in turn, increases exponentially with the number of electrons youre trying to model. By the time you have 50 electrons, you have 2 to the 50th power calculations, Gil says. Thats a phenomenally large number, so we cant compute it today, he says. (For the record, its 1.125 quadrillion. So if you fired up your laptop and started cranking through several calculations a second, it would take a few million years to run through them all.) Connecting information theory to physics could provide a path to solving such problems, Gil says. A 50-qubit quantum computer might begin to be able to do it.

Landon Downs, president and co-founder of 1QBit, says its now becoming possible to unlock the computational power of the quantum world. This has huge implications for producing new materials or creating new drugs, because we can actually move from a paradigm of discovery to a new era of quantum design, he says in an email. Rigetti, whose company is building hybrid quantum-classical machines, says one moonshot use of quantum computing could be to model catalysts that remove carbon and nitrogen from the atmosphereand thereby help fix global warming. (Bloomberg Beta LP, a venture capital unit of Bloomberg LP, is an investor in Rigetti Computing.)

The quantum-computing community hums with activity and excitement these days. Teams around the worldat startups, corporations, universities, and government labsare racing to build machines using a welter of different approaches to process quantum information. Superconducting qubit chips too elementary for you? How about trapped ions, which have brought together researchers from the University of Maryland and the National Institute of Standards and Technology? Or maybe the topological approach that Microsoft Corp. is developing through an international effort called Station Q? The aim is to harness a particle called a non-abelian anyonwhich has not yet been definitively proven to exist.

These are early days, to be sure. As of late May, the number of quantum computers in the world that clearly, unequivocally do something faster or better than a classical computer remains zero, according to Scott Aaronson, a professor of computer science and director of the Quantum Information Center at the University of Texas at Austin. Such a signal event would establish quantum supremacy. In Aaronsons words: That we dont have yet.

Yet someone may accomplish the feat as soon as this year. Most insiders say one clear favorite is a group at Google Inc. led by John Martinis, a physics professor at the University of California at Santa Barbara. According to Martinis, the groups goal is to achieve supremacy with a 49-qubit chip. As of late May, he says, the team was testing a 22-qubit processor as an intermediate step toward a showdown with a classical supercomputer. We are optimistic about this, since prior chips have worked well, he said in an email.

The idea of usingquantum mechanics to process information dates back decades. One key event happened in 1981, when International Business Machines Corp. and MIT co-sponsored a conference on the physics of computation at the universitys Endicott House in Dedham, Mass. At the conference, Richard Feynman, the famed physicist, proposed building a quantum computer. Nature isnt classical, dammit, and if you want to make a simulation of nature, youd better make it quantum mechanical, he said in his talk. And by golly, its a wonderful problem, because it doesnt look so easy.

He got that part right. The basic idea is to take advantage of a couple of the weird properties of the atomic realm: superposition and entanglement. Superposition is the mind-bending observation that a particle can be in two states at the same time. Bring out your ruler to get a measurement, however, and the particle will collapse into one state or the other. And you wont know which until you try, except in terms of probabilities. This effect is what underlies Schrdingers cat, the thought-experiment animal thats both alive and dead in a box until you sneak a peek.

Sure, bending your brain around that one doesnt come especially easy; nothing in everyday life works that way, of course. Yet about 1 million experiments since the early 20th century show that superposition is a thing. And if superposition happens to be your thing, the next step is figuring out how to strap such a crazy concept into a harness.

An IBM quantum-computing processor mounted on a circuit board. The silicon chip in the center contains several quantum bits, or qubits.

Photographer: Christopher Payne for Bloomberg Markets

Enter qubits. Classical bits can be a 0 or a 1; run a string of them together through logic gates (AND, OR, NOT, etc.), and youll multiply numbers, draw an image, and whatnot. A qubit, by contrast, can be a 0, a 1, or both at the same time, says IBMs Gil.

Ready for entanglement? (Youre in good company if you balk; Albert Einstein famously rebelled against the idea, calling it spooky action at a distance.) Well, lets say two qubits were to get entangled; Gil says that would make them perfectly correlated. A quantum computer could then utilize a menagerie of distinctive logic gates. The so-called Hadamard gate, for example, puts a qubit into a state of perfect superposition. (There may be something called a square root of NOT gate, but lets take a pass on that one.) If you tap the superposition and entanglement in clever arrangements of the weird quantum gates, you start to get at the potential power of quantum computing.

If you have two qubits, you can explore four states: 00, 01, 10, and 11. (Note that thats 4: 2 raised to the power 2.) When I perform a logical operation on my quantum computer, I can operate on all of this at once, Gil says. And the number of states you can look at is 2 raised to the power of the number of qubits. So if you could make a 50-qubit universal quantum computer, you could in theory explore all of those 1.125 quadrillion statesat the same time.

What gives quantum computing its special advantage, says Aaronson, of the University of Texas, is that quantum mechanics is based on things called amplitudes. Amplitudes are sort of like probabilities, but they can also be negativein fact, they can also be complex numbers, he says. So if you want to know the probability that something will happen, you add up the amplitudes for all the different ways that it can happen, he says.

The idea with a quantum computation is that you try to choreograph a pattern of interference so that for each wrong answer to your problem, some paths leading there have positive amplitudes and some have negative amplitudes, so they cancel each other out, Aaronson says. Whereas the paths leading to the right answer all have amplitudes that are in phase with each other. The tricky part is that you have to arrange everything not knowing in advance which answer is the right one. So I would say its the exponentiality of quantum states combined with this potential for interference between positive and negative amplitudesthats really the source of the power of quantum computing, he says.

Cover artwork: Zachary Walsh

Did we mentionthat there are problems that a classical computer cant solve? You probably harness one such difficulty every day when you use encryption on the internet. The problem is that its not easy to find the prime factors of a large number. To review: The prime factors of 15 are 5 and 3. Thats easy. If the number youre trying to factor has, say, 200 digits, its very hard. Even with your laptop running an excellent algorithm, you might have to wait years to find the prime factors.

That brings us to another milestone in quantum computing: Shors algorithm. Published in 1994 by Peter Shor, now a math professor at MIT, the algorithm demonstrated an approach that you could use to find the factors of a big numberif you had a quantum computer, which didnt exist at the time. Essentially, Shors algorithm would perform some operations that would point to the regions of numbers in which the answer was most likely to be found.

The following year, Shor also discovered a way to perform quantum error correction. Then people really got the idea that, wow, this is a different way of computing things and is more powerful in certain test cases, says Robert Schoelkopf, director of the Yale Quantum Institute and Sterling professor of applied physics and physics. Then there was a big upswelling of interest from the physics community to figure out how you could make quantum bits and logic gates between quantum bits and all of those things.

Two decades later, those things are here.

Asmundsson is editor of Bloomberg Markets.

See the rest here:

Quantum Computing Might Be Here Sooner Than You Think ... - Bloomberg

June 9, 2017 by Lisa Zyga feature (Left) False color photomicrograph and (right) simplified circuit diagram of the superconducting quantum circuit for solving 2 2 linear equations. The method uses four qubits, marked Q1 to Q4, with four corresponding readout resonators, marked R1 to R4. Credit: Zheng et al. 2017 American Physical Society

(Phys.org)Physicists have experimentally demonstrated a purely quantum method for solving systems of linear equations that has the potential to work exponentially faster than the best classical methods. The results show that quantum computing may eventually have far-reaching practical applications, since solving linear systems is commonly done throughout science and engineering.

The physicists, led by Haohua Wang at Zhejiang University and Chao-Yang Lu and Xiaobo Zhu at the University of Science and Technology of China, along with their coauthors from various institutions in China, have published their paper on what they refer to as a "quantum linear solver" in a recent issue of Physical Review Letters.

"For the first time, we have demonstrated a quantum algorithm for solving systems of linear equations on a superconducting quantum circuit," Lu told Phys.org. "[This is] one of the best solid-state platforms with excellent scalability and remarkable high fidelity."

The quantum algorithm they implemented is called the Harrow, Hassidim, and Lloyd (HHL) algorithm, which was previously shown to have the ability, in principle, to lead to an exponential quantum speedup over classical algorithms. However, so far this has not been experimentally demonstrated.

In the new study, the scientists showed that a superconducting quantum circuit running the HHL algorithm can solve the simplest type of linear system, which has two equations with two variables. The method uses just four qubits: one ancilla qubit (a universal component of most quantum computing systems), and three qubits that correspond to the input vector b and the two solutions represented by the solution vector x in the standard linear system Ax = b, where A is a 2 x 2 matrix.

By performing a series of rotations, swappings of states, and binary conversions, the HHL algorithm determines the solutions to this system, which can then be read out by a quantum nondemolition measurement. The researchers demonstrated the method using 18 different input vectors and the same matrix, generating different solutions for different inputs. As the researchers explain, it is too soon to tell how much faster this quantum method might work since these problems are easily solved by classical methods.

"The whole calculation process takes about one second," Zhu said. "It is hard to directly compare the current version to the classical methods now. In this work, we showed how to solve the simplest 2 x 2 linear system, which can be solved by classical methods in a very short time. The key power of the HHL quantum algorithm is that, when solving an 's-sparse' system matrix of a very large size, it can gain an exponential speed-up compared to the best classical method. Therefore, it would be much more interesting to show such a comparison when the size of the linear equation is scaled to a very large system."

The researchers expect that, in the future, this quantum circuit could be scaled up to solve larger linear systems. They also plan to further improve the system's performance by making some straightforward adjustments to the device fabrication to reduce some of the error in its implementation. In addition, the researchers want to investigate how the circuit could be used to implement other quantum algorithms for a variety of large-scale applications.

"Our future research will focus on improving the hardware performance, including longer coherence times, higher precision logic gates, larger numbers of qubits, lower crosstalk, better readout fidelity, etc.," Wang said. "Based on the improvement of the hardware, we will demonstrate and optimize more quantum algorithms to really show the power of the superconducting quantum processor."

Explore further: Physicists uncover similarities between classical and quantum machine learning

More information: Yarui Zheng et al. "Solving Systems of Linear Equations with a Superconducting Quantum Processor." Physical Review Letters. DOI: 10.1103/PhysRevLett.118.210504. Also at arXiv:1703.06613 [quant-ph]

2017 Phys.org

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(Phys.org)Physicists have experimentally demonstrated a purely quantum method for solving systems of linear equations that has the potential to work exponentially faster than the best classical methods. The results show ...

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I don't know why people say there are no quantum computers. And this one executes not a niche function like simulated annealing but the highly applicable system of linear equations. It really is a breakthrough.

Interesting but not much advanced beyond analog computers of the 1970s.

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Solving systems of linear equations with quantum mechanics - Phys.Org

WYOMING A University of Wyoming graduate student has received a National Science Foundation (NSF) fellowship that is taking him to New Zealand this summer to study quantum mechanics.

Josh Heiner, who is pursuing a Ph.D. in UWs Department of Physics and Astronomy, received funding for the research under NSFs East Asia and Pacific Summer Institutes program, in conjunction with the Royal Society of New Zealand.

Heiner will work with Dr. Joshua Bodyfelt, a research officer with the New Zealand Institute for Advanced Study, who earned his bachelors degree in physics from UW in 2003.

I was able to make this contact because (Bodyfelt) is an alumnus who has kept in contact with our department at UW, Heiner says. Basically, he has the expertise and skill set needed to help model an innovative way to understand the interaction of subatomic particles, also known as quantum mechanics.

Heiner works under UW physics Professor David Thayer, who was the first to suggest the innovative nonlinear dynamic modeling of quantum particles.

Heiner will work under Dr. Bodyfelts supervision to seek further insights into the new approach, preliminary results of which were published last month by Heiner and Thayer in the International Journal of Advanced Research in Physical Science. Heiner will have access to a supercomputer at Massey University in Auckland, New Zealand, for the highly complicated nonlinear computational modeling involved in the research.

Heiner, who is originally from Star Valley, received his bachelors degree from Brigham Young University-Idaho in 2014 and then came to UW to pursue graduate studies.

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UW Grad Student from Star Valley Earns Quantum Mechanics Fellowship - SweetwaterNOW.com

June 6, 2017

Scientists all over the world are working towards new methods to realize an unhackable internet, an internet based on quantum entanglement an invisible quantum mechanical connection as networking links. The greatest challenge is scaling to large networks that share entangled links with many particles and network nodes. Researchers in Delft and Oxford have now managed to distil a strong entangled link by combining multiple weaker quantum links into one. This method is essential to realize a trustworthy quantum network between several quantum nodes. This innovative new work has now been published in Science magazine.

Spooky internet

Safe communication is one of today's greatest digital challenges. There is a world-wide scientific effort towards new methods to realize a truly safe internet based on the laws of quantum mechanics. With such networks, secret eavesdropping is fundamentally impossible. However, realizing strong links in a quantum network, based on the powerful but fragile principle of quantum entanglement, is a great scientific challenge.

"Entangled particles behave as one, independent of distance. Any observation of such entangled electrons result in correlated information," Professor Ronald Hanson explains. Measuring one particle therefore instantaneously influences the other, even when they are light-years apart. Albert Einstein did not believe such a connection could exist, but a carefully designed experiment from the group of Professor Hanson in Delft in 2015 reached the world press for showing that this really is the case. They were able to succeed at this long-standing challenge by entangling quantum information over distances of over a kilometre via light particles. Scientists are now working towards ground-breaking technologies based on entanglement. Strong connections via quantum entanglement can be the basis for information sharing. 'The information exists at both places and there is no need for sensitive information to travel in between," Hanson elaborates, "we expect fundamentally safe future networks based on entanglement between quantum nodes: a quantum internet." The power of quantum entanglement is that it is invisible for third parties: the information is impossible to eavesdrop.

Entanglement distillation

The research group of Ronald Hanson at QuTech is famous for realizing networking links based on quantum entanglement. They are now building on this work to construct the first quantum internet. Ronald Hanson: "We are now taking an important step forward. Whereas we first realized entangled information between two electrons in diamonds, we now also are using one of the nuclear spins present in each diamond to temporarily store the entangled information." With the information stored safely, the scientist can entangle the electrons again. Hanson: 'Now we have two entanglement links. By combining these in a smart way, we manage to generate one strongly entangled link using two weaker entangled links, just like distilling whisky out of lower-alcoholic ingredients." In principle, this process of entanglement distillation can be repeated over and over, until high-quality entanglement is obtained."

Extending possibilities

The demonstrated method is an important step towards the quantum internet. Norbert Kalb, one of the leading authors of the paper: "To realize such a network, we need all the ingredients of the current internet: a memory, a processor and networking links. Now we have demonstrated that nuclear spins can be employed as memories that are not disturbed by regenerating entanglement between the electron spins, the processors," says Kalb.

In this publication, Hanson and his team showed that entanglement can be stored in nuclear spins while regenerating entanglement between electron spins. Hanson explains the future possibilities: "We could now entangle electrons in additional quantum nodes such that we can extend the number of networking links towards a first real quantum network. Scientifically, a whole new world opens up." This entanglement distillation is essential for the future quantum internet, which requires multiple networking links of high quality. Hanson thinks the future is within reach: "In five years we will connect four Dutch cities in a rudimentary quantum network."

Explore further: Envisioning a future quantum internet

More information: Entanglement Distillation between Solid-State Quantum Network Nodes. Science, DOI: 10.1126/science.aan0070 , https://arxiv.org/abs/1703.03244

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There's more to hacking than just listening in.

The other thing in the real world is that wiretapping is a small part of listening in, a large part is the backdoor which transmits the data out for 'debugging purposes' which 'accidentally' gets triggered by a hack, sending data to wherever. But its cool stuff nonetheless, just to have it be possible.

Also, quantum cryptography is still vulnerable to man-in-the-middle attacks. I think they're exaggerating with the unCRackable claims.

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One step closer to the quantum internet by distillation - Phys.Org

Hear us out

June 5, 2017 Marielle Wakim Theater

In The Road Not Taken, Robert Frost wrote, Two roads diverged in a yellow wood / And sorry I could not travel both. But what if you could travel both? What if an alternate version of you is traveling the other road right now, except youre wearing cleaner jeans and went with cereal, not eggs, for breakfast? That mind-melting concept is the basis of Constellations, a two-character play opening June 6 at the Geffen Playhouse.

Photograph by Luke Fontana

Playwright Nick Payne conceived his career-launching 2012 drama after stumbling on The Elegant Universe, a documentary by physicist Brian Greene. It turned Payne onto the Quantum Multiverse, the idea that different scenarios play out in endless parallel realities. Constellations zooms in on the infinite loop lived by beekeeper Roland (Downton Abbeys Allen Leech) and cosmologist Marianne (Once Upon a Times Ginnifer Goodwin). Take, for instance, the pairs introduction at a barbecue, a meeting that is repeated a few times over to various ends: In one version, Roland has a girlfriend. In another, hes married. Theres a round in which Marianne wins him over with small talk and another when she doesnt. Over 70 minutes, they break up and stay together, marry and divorce, cheat on and stay true to each other. The effect is engrossing, fueling daydreams about what couldve been if only wed taken the red pill instead of the blue. Chance is our saving grace and our Achilles heel, Payne once wrote. We are both wildly autonomous and utterly powerless.

Goodwin, for whom quantum physics is a pastime (really), calls the plays structure enrapturing. She may be biased, but audiences were smitten when the production ran in London and, three years later, on Broadway, where Jake Gyllenhaal and Ruth Wilson (The Affair) starred. Critics felt the same, if not a little mystified; The New Yorkers John Lahr described it as a singular astonishment but also admitted that he hadnt grasped for certain what it means. Payne is in the same boat. I dont really know what its meaning is, he says. Im very happy not to know and to allow audiences to take from it what they wish. I suspect it might be more about death and love, though, than it is about theoretical physics.

Tags: Allen Leech, Constellations, Downton Abbey, Ginnifer Goodwin, Once Upon A Time, The Geffen Playhouse

This article originally appeared in the June 2017 issue.

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Quantum Physics and Love are Super Weird and Confusing, but This Play Makes Sense of Them Both - LA Magazine

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It's widely abused as a buzzword. But can quantum mechanics explain how we think? National Post But deterministic physics is outdated. The core of quantum mechanics is that there is not much certain at the subatomic level. Everything is more or less potential, probabilistic, at least until you observe and measure it. Then, the various ...

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It's widely abused as a buzzword. But can quantum mechanics explain how we think? - National Post