Category Archives: Quantum Physics

June 27, 2017 UQ's Mr Nicolas Mauranyapin, Professsor Warwick Bowen and Dr Lars Madsen. Credit: University of Queensland

A diagnostic technique that can detect tiny molecules signalling the presence of cancer could be on the horizon.

The possibility of an entirely new capability for detecting cancer at its earliest stages arises from University of Queensland physicists applying quantum physics to single molecule sensing for the first time.

Australian Research Council Future Fellow Professor Warwick Bowen said the research reported in Nature Photonics this week demonstrated how quantum technologies could revolutionise the study of life's "nanoscale machinery, or biological motor molecules".

"Motor molecules encode our genetic material, create the energy our cells use to function, and distribute nutrients at a sub-cellular level," Professor Bowen said.

"Unlike methods currently available, the technique helps us observe the behaviour of single biomolecules without large-label particles or damaging light intensities."

PhD student Nicolas Mauranyapin said motor molecules drove all of life's primary functions, but scientists did not yet completely understand their workings.

"Our research opens a new door to study motor molecules in their native state, at the nanoscale," Mr Mauranyapin said.

Project researcher Dr Lars Madsen said the project applied techniques used to detect gravitational waves from black holes in outer space to the nanoscale super small world of molecular biology.

"The techniques required to detect extremely faint signals produced by distant black holes were developed over decades," Dr Madsen said.

"Our research translates this technological development over to the biosciences and offers the possibility of a new biomedical diagnostics technique capable of detecting the presence of even a single cancer marker molecule."

Researchers from five countries - Australia, New Zealand, Denmark, France and Pakistan were involved in the project.

It is funded by the United States Air Force Office of Scientific Research, which aims to use the technique to help understand stress on pilot behaviour at the sub-cellular level.

The project is part of the University of Queensland Precision Sensing Initiative, a joint initiative of the schools of Mathematics and Physics and of Information Technology and Electrical Engineering.

It was supported by the ARC Centre of Excellence for Engineered Quantum Systems, which aims to develop next-generation quantum technologies for future Australian industries.

Explore further: UQ, partners taking computing out of this world

More information: N. P. Mauranyapin et al. Evanescent single-molecule biosensing with quantum-limited precision, Nature Photonics (2017). DOI: 10.1038/nphoton.2017.99

University of Queensland researchers have partnered with global technology leader Lockheed Martin to develop next generation computers for aerospace applications.

A new nanoscale sensor has been developed that can help detect cytokinesmolecules that play a critical role in cellular response to infection, inflammation, trauma and disease.

(Phys.org)A team of Australian scientists has developed a powerful microscope using the laws of quantum mechanics to probe the inner workings of living cells.

Next-generation sensors to be used in fields as diverse as mineral exploration and climate change will be turbo boosted thanks to University of Queensland and University of Sussex research.

A team of theoretical physicists has proposed a way to simulate black holes on an electronic chip. Additionally, the technology used to create these lab-made black holes may be useful for quantum technologies. The researchers ...

Quantum mechanics rules. It dictates how particles and forces interact, and thus how atoms and molecules workfor example, what happens when a molecule goes from a higher-energy state to a lower-energy one. But beyond the ...

A diagnostic technique that can detect tiny molecules signalling the presence of cancer could be on the horizon.

A new strategy for sending acoustic waves through water could potentially open up the world of high-speed communications activities underwater, including scuba diving, remote ocean monitoring, and deep-sea exploration.

At the moment they come together, the individual grains in materials like sand and snow appear to have exactly the same probability of combining into any one of their many billions of possible arrangements, researchers have ...

An international team of researchers, working at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley, fabricated an atomically thin material and measured its exotic and durable ...

Using an off-the-shelf camera flash, researchers turned an ordinary sheet of graphene oxide into a material that bends when exposed to moisture. They then used this material to make a spider-like crawler and claw robot that ...

(Phys.org)A team of researchers from institutions in Australia, the U.S. and China has developed a functional prototype nonvolatile ferroelectric domain wall memory. In their paper published on the open access site Science ...

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Physicists make quantum leap in understanding life's nanoscale machinery - Phys.Org

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.

When a two-body relation becomes a three-body relation, the behaviour of the system changes and typically becomes more complex. While the basic physics of two interacting particles is well understood, the mathematical description ...

Some years ago, Rudolf Grimm's team of quantum physicists in Innsbruck provided experimental proof of Efimov states a phenomenon that until then had been known only in theory. Now they have also measured the second Efimov ...

(Phys.org) Chemical reactions drive the mechanisms of life as well as a million other natural processes on earth. These reactions occur at a wide spectrum of temperatures, from those prevailing at the chilly polar icecaps ...

A diagnostic technique that can detect tiny molecules signalling the presence of cancer could be on the horizon.

A new strategy for sending acoustic waves through water could potentially open up the world of high-speed communications activities underwater, including scuba diving, remote ocean monitoring, and deep-sea exploration.

At the moment they come together, the individual grains in materials like sand and snow appear to have exactly the same probability of combining into any one of their many billions of possible arrangements, researchers have ...

An international team of researchers, working at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley, fabricated an atomically thin material and measured its exotic and durable ...

Using an off-the-shelf camera flash, researchers turned an ordinary sheet of graphene oxide into a material that bends when exposed to moisture. They then used this material to make a spider-like crawler and claw robot that ...

(Phys.org)A team of researchers from institutions in Australia, the U.S. and China has developed a functional prototype nonvolatile ferroelectric domain wall memory. In their paper published on the open access site Science ...

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We cannot have nonsense particles without complete annihilation, also a little magic! But no science!

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

In theory, quantum computers could be vastly superior to regular or classical computers in performing certain kinds of tasks, but its been hard to build one. Already a leader in this field, Google is now testing its most powerful quantum chip yet,a 20-qubit processor,which the company looks to more than double in power to 49 qubits by the end of 2017.

Google's qubit devices are built on integrated circuits and can perform calculations using the physics of quantum mechanics.Qubits(or quantum bits) are units of quantum information that can be a mix of 0 and 1at the same time,making them better suited than classical bits for encoding large amounts of data.

Last year, Google actually released a plan on how it will achieve what it called quantum supremacy - getting quantum computers to do something the classical computers cannot, like factoring very large numbers. The paper says that if the processors manage to get to 50 qubits, quantum supremacy would be possible.

One big issue for Google to resolve - figuring out how to simulate what randomly arranged quantum circuits would do. Even a small difference in input into such a system would produce extremely different outputs, requiring a great amount of computing power that doesnt currently exist.

Theyre doing a quantum version of chaos, is how Simon Devitt from the RIKEN Center for Emergent Matter Science in Japan described Googles challenge. The output is essentially random, so you have to compute everything.

Computational difficulties aside, Google and other companies like IBM are moving along quicker than expected in their development. While they figured out the science necessary to create the qubits, the next challenges lie in scaling down their systems and reducing error rates.

The engineer Alan Ho from Googles quantum AI lab revealed that his teams current 20-qubit system has the error measure also known as two-qubit fidelity of 99.5%. The goal for the 49-qubit system would be to reach 99.7% fidelity.

It might take until 2027 until we get error-free quantum computers, according to Ho, meaning that usable devices are still some time away.

For more on how quantum computing works, check out this video:

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Google to Achieve "Supremacy" in Quantum Computing by the End of 2017 - Big Think

While many of us were preoccupied with ISC 2017 last week, the launch of the Chicago Quantum Exchange went largely unnoticed. So what is such a thing? It is a Department of Energy sponsored collaboration between the University of Chicago, Fermi National Accelerator Laboratory, and Argonne National Laboratory to facilitate the exploration of quantum information and the development of new applications with the potential to dramatically improve technology for communication, computing and sensing.

The new hub will be within within the Institute for Molecular Engineering (IME) at UChicago. Quantum mechanics, of course, governs the behavior of matter at the atomic and subatomic levels in exotic and unfamiliar ways compared to the classical physics used to understand the movements of everyday objects. The engineering of quantum phenomena could lead to new classes of devices and computing capabilities, permitting novel approaches to solving problems that cannot be addressed using existing technology.

Lately, it seems work on quantum computing has ratcheted up considerably with IBM, Google, D-Wave, and Microsoft leading the charge. The Chicago Quantum Exchange seems to be a more holistic endeavor to advance the entire quantum research ecosystem and industry.

The combination of the University of Chicago, Argonne National Laboratory and Fermi National Accelerator Laboratory, working together as the Chicago Quantum Exchange, is unique in the domain of quantum information science, said Matthew Tirrell, dean and Founding Pritzker Director of the Institute for Molecular Engineering and Argonnes deputy laboratory director for science. The CQEs capabilities will span the range of quantum information, from basic solid state experimental and theoretical physics, to device design and fabrication, to algorithm and software development. CQE aims to integrate and exploit these capabilities to create a quantum information technology ecosystem.

According to the official announcement, the CQE collaboration will benefit from UChicagosPolsky Center for Entrepreneurship and Innovation, which supports the creation of innovative businesses connected to UChicago and Chicagos South Side. The CQE will have a strong connection with a major Hyde Park innovation project that wasannounced recentlyas the second phase of the Harper Court development on the north side of 53rd Street, and will include an expansion of Polsky Center activities. This project will enable the transition from laboratory discoveries to societal applications through industrial collaborations and startup initiatives.

Companies large and small are positioning themselves to make a far-reaching impact with this new quantum technology. Alumni of IMEs quantum engineering PhD program have been recruited to work for many of these companies. The creation of CQE will allow for new linkages and collaborations with industry, governmental agencies and other academic institutions, as well as support from the Polsky Center for new startup ventures.

IMEs quantum engineering program is already training a new workforce of quantum engineers to meet the need of industry, government laboratories, and universities. The program now consists of eight faculty members and more than 100 postdoctoral scientists and doctoral students. Approximately 20 faculty members from UChicagos Physical Sciences Division also pursue quantum research.

Source: University of Chicago

Link to full article: https://news.uchicago.edu/article/2017/06/20/chicago-quantum-exchange-create-technologically-transformative-ecosystem

The rest is here:

DoE Launches Chicago Quantum Exchange - HPCwire (blog)

June 23, 2017 Single spins in silicon carbide absorb and emit single photons based on the state of their spin. Credit: Prof. David Awschalom

An international team led by the University of Chicago's Institute for Molecular Engineering has discovered how to manipulate a weird quantum interface between light and matter in silicon carbide along wavelengths used in telecommunications.

The work advances the possibility of applying quantum mechanical principles to existing optical fiber networks for secure communications and geographically distributed quantum computation. Prof. David Awschalom and his 13 co-authors announced their discovery in the June 23 issue of Physical Review X.

"Silicon carbide is currently used to build a wide variety of classical electronic devices today," said Awschalom, the Liew Family Professor in Molecular Engineering at UChicago and a senior scientist at Argonne National Laboratory. "All of the processing protocols are in place to fabricate small quantum devices out of this material. These results offer a pathway for bringing quantum physics into the technological world."

The findings are partly based on theoretical models of the materials performed by Awschalom's co-authors at the Hungarian Academy of Sciences in Budapest. Another research group in Sweden's Linkping University grew much of the silicon carbide material that Awschalom's team tested in experiments at UChicago. And another team at the National Institutes for Quantum and Radiological Science and Technology in Japan helped the UChicago researchers make quantum defects in the materials by irradiating them with electron beams.

Quantum mechanics govern the behavior of matter at the atomic and subatomic levels in exotic and counterintuitive ways as compared to the everyday world of classical physics. The new discovery hinges on a quantum interface within atomic-scale defects in silicon carbide that generates the fragile property of entanglement, one of the strangest phenomena predicted by quantum mechanics.

Entanglement means that two particles can be so inextricably connected that the state of one particle can instantly influence the state of the other, no matter how far apart they are.

"This non-intuitive nature of quantum mechanics might be exploited to ensure that communications between two parties are not intercepted or altered," Awschalom said.

Exploiting quantum mechanics

The findings enhance the once-unexpected opportunity to create and control quantum states in materials that already have technological applications, Awschalom noted. Pursuing the scientific and technological potential of such advances will become the focus of the newly announced Chicago Quantum Exchange, which Awschalom will direct.

An especially intriguing aspect of the new paper was that silicon carbide semiconductor defects have a natural affinity for moving information between light and spin (a magnetic property of electrons). "A key unknown has always been whether we could find a way to convert their quantum states to light," said David Christle, a postdoctoral scholar at the University of Chicago and lead author of the work. "We knew a light-matter interface should exist, but we might have been unlucky and found it to be intrinsically unsuitable for generating entanglement. We were very fortuitous in that the optical transitions and the process that converts the spin to light is of very high quality."

The defect is a missing atom that causes nearby atoms in the material to rearrange their electrons. The missing atom, or the defect itself, creates an electronic state that researchers control with a tunable infrared laser.

"What quality basically means is: How many photons can you get before you've destroyed the quantum state of the spin?" said Abram Falk, a researcher at the IBM Thomas J. Watson Resarch Center in Yorktown Heights, N.Y., who is familiar with the work but not a co-author on the paper.

The UChicago researchers found that they could potentially generate up to 10,000 photons, or packets of light, before they destroyed the spin state. "That would be a world record in terms of what you could do with one of these types of defect states," Falk added.

Awschalom's team was able to turn the quantum state of information from single electron spins in commercial wafers of silicon carbide into light and read it out with an efficiency of approximately 95 percent.

Millisecond coherence

The duration of the spin statecalled coherencethat Awschalom's team achieved was a millisecond. Not much by clock standards, but quite a lot in the realm of quantum states, in which multiple calculations can be carried out in a nanosecond, or a billionth of a second.

The feat opens up new possibilities in silicon carbide because its nanoscale defects are a leading platform for new technologies that seek to use quantum mechanical properties for quantum information processing, sensing magnetic and electric fields and temperature with nanoscale resolution, and secure communications using light.

"There's about a billion-dollar industry of power electronics built on silicon carbide," Falk said. "Following this work, there's an opportunity to build a platform for quantum communication that leverages these very advanced classical devices in the semiconductor industry," he said.

Most researchers studying defects for quantum applications have focused on an atomic defect in diamond, which has become a popular visible-light testbed for these technologies.

"Diamond has been this huge industry of quantum control work," Falk noted. Dozens of research groups across the country have spent more than a decade perfecting the material to achieve standards that Awschalom's group has mastered in silicon carbide after only a few years of investigation.

Silicon carbide versatility

"There are many different forms of silicon carbide, and some of them are commonly used today in electronics and optoelectronics," Awschalom said. "Quantum states are present in all forms of silicon carbide that we've explored. This bodes well for introducing quantum mechanical effects into both electronic and optical technologies."

Researchers now are beginning to wonder if this type of physics also may work in other materials, Falk noted.

"Moreover, can we rationally design a defect that has the properties we want, not just stumble into one?" he asked.

Defects are the key.

"For decades the electronics industry has come up with a myriad of tricks to remove all the defects from their devices because defects often cause problems in conventional electronics," Awschalom explained. "Ironically, we're putting the defects back in for quantum systems."

Explore further: Exceptionally robust quantum states found in industrially important semiconductor

More information: "Isolated Spin Qubuits in SiC with a High-Fidelity Infrared Spin-to-Photon Interface," Physical Review X (2017). journals.aps.org/prx/abstract/10.1103/PhysRevX.7.021046

Harnessing solid-state quantum bits, or qubits, is a key step toward the mass production of electronic devices based on quantum information science and technology. However, realizing a robust qubit with a long lifetime is ...

A discovery by physicists at UC Santa Barbara may earn silicon carbide -- a semiconductor commonly used by the electronics industry -- a role at the center of a new generation of information technologies designed to exploit ...

Quantum computersa possible future technology that would revolutionize computing by harnessing the bizarre properties of quantum bits, or qubits. Qubits are the quantum analogue to the classical computer bits "0" and "1." ...

An electronics technology that uses the "spin" - or magnetization - of atomic nuclei to store and process information promises huge gains in performance over today's electron-based devices. But getting there is proving challenging.

For 60 years computers have become smaller, faster and cheaper. But engineers are approaching the limits of how small they can make silicon transistors and how quickly they can push electricity through devices to create digital ...

Entanglement is one of the strangest phenomena predicted by quantum mechanics, the theory that underlies most of modern physics. It says that two particles can be so inextricably connected that the state of one particle can ...

An international team led by the University of Chicago's Institute for Molecular Engineering has discovered how to manipulate a weird quantum interface between light and matter in silicon carbide along wavelengths used in ...

Researchers at the U.S. Department of Energy's Ames Laboratory discovered that they could functionalize magnetic materials through a thoroughly unlikely method, by adding amounts of the virtually non-magnetic element scandium ...

(Phys.org)In the late 1800s when scientists were still trying to figure out what exactly atoms are, one of the leading theories, proposed by Lord Kelvin, was that atoms are knots of swirling vortices in the aether. Although ...

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

Researchers from the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder have demonstrated a new mobile, ground-based system that could scan and map atmospheric gas plumes over kilometer ...

In experiments at the Department of Energy's SLAC National Accelerator Laboratory, scientists were able to see the first step of a process that protects a DNA building block called thymine from sun damage: When it's hit with ...

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How many times is Phys.org going to repeat this fallacy ?

The distance of this influence is definitely limited by decoherence, i.e. the tendency of vacuum fluctuations (which manifest itself like the CMB radiation and thermal noise) to disrupt the entangled state (i.e. to desynchronize pilot waves of entangled objects). Inside the diamond or silicon carbide (which is similar to diamond in many extents) the strength of bonds between atoms is so high, that the effects of thermal vibrations are diminished, which makes these materials perspective systems for storage of spin and another states of atoms. I just don't think, that these states are quantized, because they require many quanta of energy (more than 10.000 photons) for switching their spin state. IMO they're rather close to classical systems of storage information within laser pulses, like the layers of dyes etc.. The another question whether the speed of this influence is infinite is also disputable, despite that we have indicia, in pure quantum system it gets actually superluminal.

Entanglement is two photons created at the source with opposite spins which sum to zero. There is no such thing as spooky action at a distance, full stop.

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Atomic imperfections move quantum communication network closer ... - 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

Better thermometers might be possible as a result of a discovery at the National Institute of Standards and Technology (NIST), where physicists have found a way to calibrate temperature measurements by monitoring the tiny ...

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Elemental metals usually form simple, close-packed crystalline structures. Though lithium (Li) is considered a typical simple metal, its crystal structure at ambient pressure and low temperature remains unknown.

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, ...

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Quantum thermometer or optical refrigerator? - Phys.org - 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.

Continued here:

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.

Follow Jack Ewing on Twitter @JackEwingNYT.

A version of this article appears in print on June 23, 2017, on Page B4 of the New York edition with the headline: Europes Car Giants Race to Outsmart Apple and Google.

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

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

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.

Read more here:

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