Category Archives: Quantum Physics

Bagatelle or pin-board game. Credit: Lorenzo Nocchi

Researchers from the Austrian Academy of Sciences, the University of Vienna and the University of Geneva, have proposed a new interpretation of classical physics without real numbers. This new study challenges the traditional view of classical physics as deterministic.

In classical physics it is usually assumed that if we know where an object is and its velocity, we can exactly predict where it will go. An alleged superior intelligence having the knowledge of all existing objects at present, would be able to know with certainty the future as well as the past of the universe with infinite precision. Pierre-Simon Laplace illustrated this argument, later called Laplaces demon, in the early 1800s to illustrate the concept of determinism in classical physics. It is generally believed that it was only with the advent of quantum physics that determinism was challenged. Scientists found out that not everything can be said with certainty and we can only calculate the probability that something could behave in a certain way.

But is really classical physics completely deterministic? Flavio Del Santo, researcher at Vienna Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences and the University of Vienna, and Nicolas Gisin from the University of Geneva, address this question in their new article Physics without Determinism: Alternative Interpretations of Classical Physics, published in the journal Physical Review A.

Building on previous works of the latter author, they show that the usual interpretation of classical physics is based on tacit additional assumptions. When we measure something, say the length of a table with a ruler, we find a value with a finite precision, meaning with a finite number of digits. Even if we use a more accurate measurement instrument, we will just find more digits, but still a finite number of them. However, classical physics assumes that even if we may not be able to measure them, there exist an infinite number of predetermined digits. This means that the length of the table is always perfectly determined.

Imagine now to play a variant of the Bagatelle or pin-board game (as in figure), where a board is symmetrically filled with pins. When a little ball rolls down the board, it will hit the pins and move either to the right or to the left of each of them. In a deterministic world, the perfect knowledge of the initial conditions under which the ball enters the board (its velocity and position) determines unambiguously the path that the ball will follow between the pins. Classical physics assumes that if we cannot obtain the same path in different runs, it is only because in practice we were not able to set precisely the same initial conditions. For instance, because we do not have an infinitely precise measurement instrument to set the initial position of the ball when entering the board.

The authors of this new study propose an alternative view: after a certain number of pins, the future of the ball is genuinely random, even in principle, and not due to the limitations of our measurement instruments. At each hit, the ball has a certain propensity or tendency to bounce on the right or on the left, and this choice is not determined a priori. For the first few hits, the path can be determined with certainty, that is the propensity is 100% for the one side and 0% for the other. After a certain number of pins, however, the choice is not pre-determined and the propensity gradually reaches 50% for the right and 50% for the left for the distant pins. In this way, one can think of each digit of the length of our table as becoming determined by a process similar to the choice of going left or right at each hit of the little ball. Therefore, after a certain number of digits, the length is not determined anymore.

The new model introduced by the researchers hence refuses the usual attribution of a physical meaning to mathematical real numbers (numbers with infinite predetermined digits). It states instead that after a certain number of digits their values become truly random, and only the propensity of taking a specific value is well defined. This leads to new insights on the relationship between classical and quantum physics. In fact, when, how and under what circumstances an indeterminate quantity takes a definite value is a notorious question in the foundations of quantum physics, known as the quantum measurement problem. This is related to the fact that in the quantum world it is impossible to observe reality without changing it. In fact, the value of a measurement on a quantum object is not yet established until an observer actually measures it. This new study, on the other hand, points out that the same issue could have always been hidden also behind the reassuring rules of classical physics.

Reference: Physics without determinism: Alternative interpretations of classical physics by Flavio Del Santo and Nicolas Gisin, 5 December 2019, Physical Review A.DOI: 10.1103/PhysRevA.100.062107

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Has Physics Ever Been Deterministic? New Insights on the Relationship Between Classical and Quantum Physics - SciTechDaily

Quantum computers will make easy work of our current encryption systems, putting some of the worlds most sensitive data at risk. And John Prisco, CEO of the security company Quantum Xchange, tells Inverse that the time for new encryption is already here.

Traditional cryptography relies on a system of public and private encrypted keys that protect data by creating a decryption process that relies on solving incredibly complex math. Namely, the factoring of prime numbers. For todays computers, trying to solve the answer through brute force (e.g. guessing as many different answers as possible) would be nearly impossible. But for quantum computers, such computational hurdles would be trivial.

Before computers were as powerful as they are today, that [kind of cryptography] was going to be good for a million years, says Prisco. [But] a million years got truncated into just a handful of years.

But such computational might, for the time being, is still fairly theoretical. Google was only able to achieve quantum supremacy (a benchmark that compares its computational abilities to a classical computer) this year and quantum systems are far from office staples. Yet, Prisco tells Inverse that waiting until these machines become more widespread to begin improving our encryption methods would be too late.

People are stealing data today and then harvesting [and] storing it, says Prisco. And when they crack the key, then theyve got the information. So if you have data that has a long shelf life, like personal information, personnel records, you really cant afford to not future proof that.

And government agencies says Prisco, are worried about this too. In 2017 NIST (National Institute of Science and Technology) put out a call for new, quantum-resistant algorithms. Out of the 82 submissions it received, only 26 are still being considered for implementation. But Prisco tells Inverse that simply creating algorithms to combat these advanced computers wont be enough. Instead, we need to fight quantum with quantum.

Thats where Priscos company, Quantum Xchange, comes in. Instead of focusing on quantum-resistant algorithms, Quantum Xchange creates new encryption keys that themselves rely on the physics of quantum mechanics.

Just as todays keys are made up of numbers, says Prisco, their quantum key (called QKD) would be made up of photons.

[The QKDs] photons are encoded with ones and zeros, but rather than relying on solving a difficult math problem, it relies on a property of physics, says Prisco. And that property is associated with not being able to observe a photon in any way, shape, or form without changing its quantum state.

This quantum property that Prisco refers to is a law of physics called the Heisenberg Uncertainty Principle. According to this principle, the quantum state of the QKD is only stable as long as its not observed. So, even if a nefarious actor were to steal the QKD, Prisco tells Inverse, the very act of stealing it would count as observation and would thus change the QKD altogether and render it moot.

You could steal the quantum key, says Prisco, but it would no longer be the key that was used to encrypt and therefore it would no longer be able to decrypt.

Prisco tells Inverse that he believes this new generation of quantum keys would remain resilient as long as the laws of quantum physics did. So in theory, a very, very long time.

While other experts have estimated that it will be ten years until such quantum attacks really start taking place, Prisco tells Inverse he believes it will be less than five. And waiting to develop these technologies will not only put our data at risk, but could put us behind the curve when it comes to competing with other countries in this arena as well. Particularly China, who Prisco says is outspending the U.S. 10-to-1 in quantum technology.

Going forward, Prisco says that the U.S.s best bet will be to incorporate both the quantum-resistant algorithms being developed by NIST and other government agencies as well as a quantum key like their QKD.

Im a proponent for combining what NSA and NIST are doing with quantum-resistant algorithms with quantum keys, says Prisco. You know, it may seem like a revolutionary concept in the United States but I can tell you that Chinas doing this, all of Europes doing this Russias doing this. Everybody kind of realizes that the quantum computer is an offensive weapon when it comes to cryptography. And that the first defensive weapon one can deploy are the quantum keys, and then quantum-resistant algorithms when theyre available.

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Traditional cryptography doesn't stand a chance against the quantum age - Inverse

Inside a stainless steel chamber, LIGO technicians examine the surface of one of the test mass mirrors that will reflect infrared laser light to measure the effect of gravity waves. After installation, all air was vacuumed from this chamber. (Mike Fyffe/LIGO lab)

(Inside Science) -- Physicists have successfully developed a new instrument that significantly reduces quantum-level noise that has thus far limited experiments ability to spot gravitational waves. Collisions between massive black holes and stars are thought to generate these ripples in space-time that werefirst detected in 2015. In all, about 11detections have been fully confirmed so far.

The device marks a major improvement to the Laser Interferometer Gravitational-wave Observatory, or LIGO, increasing its detection range by 15 percent. Since the sky is a sphere, scientists expect to be able to detect about 50 percent more gravitational waves. They now predict that they will catch dozens of these rarely detected events during LIGOs ongoing experiment run through April 2020, which could transform their understanding of the phenomena. The collaborationpublished their findingstoday in the journalPhysical Review Letters.

This is really the turning point, because now we can really do statistics with all these detections, said Lisa Barsotti, an MIT astrophysicist and one of the scientists leading the effort. Thats why its becoming a new era in gravitational wave astronomy.

The LIGO detector in Livingston, Louisiana. (Credit: Caltech/MIT/LIGO Lab)

LIGOs detectors in Hanford, Washington and Livingston, Louisiana reveal an incoming gravitational wave using giant interferometers. These involve lasers bouncing off mirrors and traveling along two L-shaped arms 4 kilometers in length. A gravitational wave strains the arms so that the pair of laser beams become out of phase.

But physicists ability to detect such a tiny signal is limited by seemingly insurmountable quantum noise, due to random fluctuations that slightly modulate the arrival time of photons, the smallest quantum bits of laser light. To remedy that, Barsotti and her colleagues use a quantum squeezer, a crystal in the cavity of the arms of the interferometer that manipulates the interactions between the laser and the quantum vacuum and produces smaller fluctuations among the photons.

The achievement brought together expertise in quantum physics and astrophysics and enables more sensitive detections of black holes and extremely dense neutron stars as they smash into each other. Other colliding objects, like supernova explosions and more typical stars, create gravitational waves that are still too tiny to pick out with current technologies.

Similar quantum squeezing devices are also being tested by LIGOsEuropean counterparts in Advanced Virgo, using detectors built in northern Italy. Barsotti predicts that quantum squeezed light will become the standard for all next-generation detectors, like the proposed Cosmic Explorer, which would have arms stretching 40 kilometers on the ground, further increasing its sensitivity.

[This story originally appeared on InsideScience.org.]

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New Quantum Tech is About to Bring a Major Boost to Gravitational Wave Detections - Discover Magazine

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If you're a fan of the Netflix series "Stranger Things," you've seen the climatic season three scene, in which Dustin tries to cajole his brainy long-distance girlfriend Suzie over a ham radio connection into telling him the precise value of something called Planck's constant, which also happens to be the code to open a safe that contains the keys needed to close the gate to a malevolent alternative universe.

But before Suzie will recite the magic number, she exacts a high price: Dustin has to sing the theme song to the movie "The NeverEnding Story."

This may all have led you to wonder: What exactly is Planck's constant, anyway?

The constant devised in 1900 by a German physicist named Max Planck, who would win the 1918 Nobel Prize for his work is a crucial part of quantum mechanics, the branch of physics which deals with the tiny particles that make up matter and the forces involved in their interactions. From computer chips and solar panels to lasers, "it's the physics that explains how everything works."

Planck and other physicists in the late 1800s and early 1900s were trying to understand the difference between classical mechanics that is, the motion of bodies in the observable world around us, described by Sir Isaac Newton in the late 1600s and an invisible world of the ultrasmall, where energy behaves in some ways like a wave and in some ways like a particle, also known as a photon.

"In quantum mechanics, physics works different from our experiences in the macroscopic world," explains Stephan Schlamminger, a physicist for the National Institute of Standards and Technology, by email. As an explanation, he cites the example of a familiar harmonic oscillator, a child on a swing set.

"In classical mechanics, the child can be at any amplitude (height) on the swing's path," Schlamminger says. "The energy that the system has is proportional to the square of the amplitude. Hence, the child can swing at any continuous range of energies from zero up to a certain point."

But when you get down to the level of quantum mechanics, things behave differently. "The amount of energy that an oscillator could have is discrete, like rungs on a ladder," Schlamminger says. "The energy levels are separated by h times f, where f is the frequency of the photon a particle of light an electron would release or absorb to go from one energy level to another."

In this 2016 video, another NIST physicist, Darine El Haddad, explains Planck's constant using the metaphor of putting sugar in coffee. "In classical mechanics, energy is continuous, meaning if I take my sugar dispenser, I can pour any amount of sugar into my coffee," she says. "Any amount of energy is OK."

"But Max Planck found something very different when he looked deeper, she explains in the video. "Energy is quantized, or it's discrete, meaning I can only add one sugar cube or two or three. Only a certain amount of energy is allowed."

Planck's constant defines the amount of energy that a photon can carry, according to the frequency of the wave in which it travels.

Electromagnetic radiation and elementary particles "display intrinsically both particle and wave properties," explains Fred Cooper, an external professor at the Santa Fe Institute, an independent research center in New Mexico, by email. "The fundamental constant which connects these two aspects of these entities is Planck's constant. Electromagnetic energy cannot be transferred continuously but is transferred by discrete photons of light whose energy E is given by E = hf, where h is Planck's constant, and f is the frequency of the light."

One of the confusing things for nonscientists about Planck's constant is that the value assigned to it has changed by tiny amounts over time. Back in 1985, the accepted value was h = 6.626176 x 10-34 Joule-seconds. The current calculation, done in 2018, is h = 6.62607015 x 10-34 Joule-seconds.

"While these fundamental constants are fixed in the fabric of the universe, we humans don't know their exact values," Schlamminger explains. "We have to build experiments to measure these fundamental constants to the best of humankind's ability. Our knowledge comes from a few experiments that were averaged to produce a mean value for the Planck constant."

To measure Planck's constant, scientists have used two different experiments theKibble balance and the X-ray crystal density (XRCD) method, and over time, they've developed a better understanding of how to get a more precise number. "When a new number is published, the experimenters put forward their best number as well as their best calculation of the uncertainty in their measurement," Schlamminger says. "The true, but unknown value of the constant, should hopefully lie in the interval of plus/minus the uncertainty around the published number, with a certain statistical probability." At this point, "we are confident that the true value is not far off. The Kibble balance and the XRCD method are so different that it would be a major coincidence that both ways agree so well by chance."

That tiny imprecision in scientists' calculations isn't a big deal in the scheme of things. But if Planck's constant was a significantly bigger or smaller number, "all the world around us would be completely different," explains Martin Fraas, an assistant professor in mathematics at Virginia Tech, by email. If the value of the constant was increased, for example, stable atoms might be many times bigger than stars.

The size of a kilogram, which came into force on May 20, 2019, as agreed upon by the International Bureau of Weights and Measures (whose French acronym is BIPM) is now based upon Planck's constant.

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What Is Planck's Constant, and Why Does the Universe Depend on It? - HowStuffWorks

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In 1950, a man named John Bennett, an Australian employee of the now-defunct British technology firm Ferranti, created what may be historys first gaming computer. It could play a game called Nim, a long-forgotten parlor game in which players take turns removing matches from several piles. The player who loses is the one who removes the last match. For his computerized version, Bennett created a vast machine 12 feet wide, 5 feet tall, and 9 feet deep. The majority of this space was taken up by light-up vacuum tubes which depicted the virtual matches.

Bennetts aim wasnt to create a game-playing machine for the sake of it; the reason that somebody might build a games PC today. As writer Tristan Donovan observed in Replay, his superlative 2010 history of video games: Despite suggesting Ferranti create a game-playing computer, Bennetts aim was not to entertain but to show off the ability of computers to do [math].

Jump forward almost 70 years and a physicist and computer scientist named Dr. James Robin Wootton is using games to demonstrate the capabilities of another new, and equally large, experimental computer. The computer in this question is a quantum computer, a dream of scientists since the 1980s, now finally becoming a scientific reality.

Quantum computers encode information as delicate correlations with an incredibly rich structure. This allows for potentially mind-boggling densities of information to be stored and manipulated. Unlike a classical computer, which encodes as a series of ones and zeroes, the bits (called qubits) in a quantum computer can be either a one, a zero, or both at the same time. These qubits are composed of subatomic particles, which conform to the rules of quantum rather than classical mechanics. They play by their own rules a little bit like Tom Cruises character Maverick from Top Gun if he spent less time buzzing the tower and more time demonstrating properties like superpositions and entanglement.

I met Wootton at IBMs research lab in Zurich on a rainy day in late November. Moments prior, I had squeezed into a small room with a gaggle of other excited onlookers, where we stood behind a rope and stared at one of IBMs quantum computers like people waiting to be allowed into an exclusive nightclub. I was reminded of the way that people, in John Bennetts day, talked about the technological priesthood surrounding computers: then enormous mainframes sequestered away in labyrinthine chambers, tended to by highly qualified people in white lab coats. Lacking the necessary seminary training, we quantum computer visitors could only bask in its ambience from a distance, listening in reverent silence to the weird vee-oing vee-oing vee-oing sound of its cooling system.

Wottons interest in quantum gaming came about from exactly this scenario. In 2016, he attended a quantum computing event at the same Swiss ski resort where, in 1925, Erwin Schrdinger had worked out his famous Schrdinger wave equation while on vacation with a girlfriend. If there is a ground zero for quantum computing, this was it. Wotton was part of a consortium, sponsored by the Swiss government, to do (and help spread the word about) quantum computing.

At that time quantum computing seemed like it was something that was very far away, he told Digital Trends. Companies and universities were working on it, but it was a topic of research, rather than something that anyone on the street was likely to get their hands on. We were talking about how to address this.

Wootton has been a gamer since the early 1990s. I won a Game Boy in a competition in a wrestling magazine, he said. It was a Slush Puppy competition where you had to come up with a new flavor. My Slush Puppy flavor was called something like Rollin Redcurrant. Im not sure if you had to use the adjective. Maybe thats what set me apart.

While perhaps not a straight path, Wootton knew how an interest in gaming could lead people to an interest in other aspects of technology. He suggested that making games using quantum computing might be a good way of raising public awareness of the technology.He applied for support and, for the next year, was given to my amazement the chance to go and build an educational computer game about quantum computing. At the time, a few people warned me that this was not going to be good for my career, he said. [They told me] I should be writing papers and getting grants; not making games.

But the idea was too tantalizing to pass up.

That same year, IBM launched its Quantum Experience, an online platform granting the general public (at least those with a background in linear algebra) access to IBMs prototype quantum processors via the cloud. Combined with Project Q, a quantum SDK capable of running jobs on IBMs devices, this took care of both the hardware and software component of Woottons project. What he needed now was a game. Woottons first attempt at creating a quantum game for the public was a version of the game Rock-Paper-Scissors, named Cat-Box-Scissors after the famous Schrdingers cat thought experiment. Wootton later dismissed it as [not] very good Little more than a random number generator with a story.

But others followed. There was Battleships, his crack at the first multiplayer game made with a quantum computer. There was Quantum Solitaire. There was a text-based dungeon crawler, modeled on 1973s Hunt the Wumpus, called Hunt the Quantpus. Then the messily titled, but significant, Battleships with partial NOT gates, which Wootton considers the first true quantum computer game, rather than just an experiment. And so on. As games, these dont exactly make Red Dead Redemption 2 look like yesterdays news. Theyre more like Atari 2600 or Commodore 64 games in their aesthetics and gameplay. Still, thats exactly what youd expect from the embryonic phases of a new computing architecture.

If youd like to try out a quantum game for yourself, youre best off starting with Hello Quantum, available for both iOS and Android. It reimagines the principles of quantum computing as a puzzle game in which players must flip qubits. It wont make you a quantum expert overnight, but it will help demystify the process a bit. (With every level, players can hit a learn more button for a digestible tutorial on quantum basics.)

Quantum gaming isnt just about educational outreach, though. Just as John Bennett imagined Nim as a game that would exist to show off a computers abilities, only to unwittingly kickstart a $130 billion a year industry, so quantum games are moving beyond just teaching players lessons about quantum computing.Increasingly, Wootton is excited about what he sees as real world uses for quantum computing. One of the most promising of these is taking advantage of quantum computings random number generating to create random terrain within computer games. In Zurich, he showed me a three-dimensional virtual landscape reminiscent of Minecraft. However, while much of the world of Minecraft is user generated, in this case the blocky, low-resolution world was generated using a quantum computer.

Quantum mechanics is known for its randomness, so the easiest possibility is just to use quantum computing as a , Wootton said. I have a game in which I use only one qubit: the smallest quantum computer you can get. All you can do is apply operations that change the probabilities of getting a zero or one as output. I use that to determine the height of the terrain at any point in the game map.

Plenty of games made with classical computers have already included procedurally generated elements over the years. But as the requirements for these elements ranging from randomly generated enemies to entire maps increase in complexity, quantum could help.

Gaming is an industry that is very dependent on how fast things run

Gaming is an industry that is very dependent on how fast things run, he continued. If theres a factor of 10 difference in how long it takes something to run that determines whether you can actually use it in a game. He sees today as a great jumping-on point for people in the gaming industry to get involved to help shape the future development of quantum computing. Its going to be driven by what people want, he explained. If people find an interesting use-case and everyone wants to use quantum computing for a game where you have to submit a job once per frame, that will help dictate the way that the technology is made.

Hes now reached the point where he thinks the race may truly be on to develop the first commercial game using a quantum computer. Weve been working on these proof-of-principle projects, but now I want to work with actual game studios on actual problems that they have, he continued. That means finding out what they want and how they want the technology to be [directed].

One thing thats for certain is that Wootton is no longer alone in developing his quantum games. In the last couple of years, a number ofquantum game jams have popped up around the world. What most people have done is to start small, Wootton said. They often take an existing game and use one or two qubits to help allow you to implement a quantum twist on the game mechanics. Following this mantra, enthusiasts have used quantum computing to make remixed versions of existing games, including Dr. Qubit (a quantum version of Dr. Mario), Quantum Cat-sweeper (a quantum version of Minesweeper), and Quantum Pong (a quantum version of, err, Pong).

The world of quantum gaming has moved beyond its 1950 equivalent of Nim. Now we just have to wait and see what happens next. The decades which followed Nim gave us MITs legendary Spacewar in the 1960s, the arcade boom of the 1970s and 80s, the console wars of Sega vs. Nintendo, the arrival of the Sony PlayStation in the 1990s, and so on. In the process, classical computers became part of our lives in a way they never were before. As Whole Earth Catalog founder Stewart Brand predicted as far back as 1972 Rolling Stone in his classic essay on Spacewar: Ready or not, computers are coming to the people.

At present, quantum gamings future is at a crossroads. Is it an obscure niche occupied by just a few gaming physics enthusiasts or a powerful tool that will shape tomorrows industry? Is it something that will teach us all to appreciate the finer points of quantum physics or a tool many of us wont even realize is being used, that will nevertheless give us some dope ass games to play?

Like Schrdingers cat, right now its both at once. What a superposition to be in.

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Inside the weird, wild, and wondrous world of quantum video games - Digital Trends

Paris, France, December 12, 2019 Following on from the 6thmeeting of its Quantum Scientific Council, Atos, a global leader in digital transformation, announces that it is continuing to enrich its quantum development ecosystem, through the creation of a global User Group of the Atos Quantum Learning Machine (QLM), which will be chaired by a representative from French multi-national energy company Total. This announcement follows the commercial success of the QLM, the world's highest-performing quantum programming appliance, allowing for the first time to simulate quantic behaviors. This ecosystem is supported by the Atos Quantum Scientific Council, which includes universally recognized quantum physicists. It is also further enhanced by partners such as leading software company Zapata and start-up Xofia.

Just two years on from its launch in 2017, Atos QLM users continue to grow as the QLM is being used in numerous countries worldwide includingAustria,France,Germany, Ireland, Mexico, the Netherlands,UKand theUnited States, empowering major research programs in various sectors.

The User Group will bring together current QLM customers and their ecosystems of users from around the world, including research centers, universities and global industrial companies. It will be chaired by a representative from Total, Henri Calandra, Expert in Numerical Methods and High Performance Computing. This QLM User Group aims to drive advances in quantum programming and simulation, as well as to develop and enrich collaboration between users and share best practice and support. Feedback will be used to influence Atos QLM evolutions and further enhance the technical support that it provides its customers, paving the road towards the new world of quantum computing.

Atos is committed to enrich its quantum ecosystem and with this, its research program in order to continue to provide researchers worldwide with the right conditions and solutions so that they can take advantage of the innovative opportunities provided by quantum computing. We have some of the worlds leading scientists on our Quantum Scientific Council which, together with our rich base of QLM customers, means we are creating the most advanced quantum ecosystem said Elie Girard, CEO of Atos Now, with the creation of this Group of Atos QLM Users, we are ensuring that we continue to support them to develop new advances in deep learning, algorithmics and artificial intelligence with the support of the breakthrough computing acceleration capacities that quantum simulation provides.

As President of this new User Group, Total is involved in the advancement of quantum research, together with Atos. Quantum simulationenables us to explore new ways of solving complex problems, improve performance and drive significant technological advances to prepare the future of low carbon energy. This contributes to realizing Totals ambition: to become the responsible energy major, said Marie-Noelle Semeria, Senior Vice President, Group CTO at Total.

The Quantum Scientific Council is made up of universally recognized quantum physicists, including Nobel prize laureate in Physics, Serge Haroche; Research Director, CEA Saclay, and Head of Quantronics, Daniel Estve; professor at the Institut dOptique and Ecole Polytechnique, Alain Aspect; Alexander von Humboldt Professor, Director of the Institute for Theoretical Nanoelectronics at the Juelich Research Center, David DiVincenzo; and Professor of Quantum Physics at the Mathematical Institute, University of Oxford and Singapore, Artur Ekert.

Atos ambitious program to anticipate the future of quantum computing and to be prepared for the opportunities as well as the risks that come with it - Atos Quantum program - was launched in November 2016. As a result of this initiative,Atos was the first organization to offer a quantum noisy simulation module, the Atos QLM. Earlier this year, it launched myQLM, a free tool that allows a broader ecosystem to get acquainted with quantum programming and discover some features of the Atos QLM.

Quantum computing should make it possible, in the years to come, to deal with the explosion of data, which Big Data and the Internet of Things bring about. With its targeted and unprecedented compute acceleration capabilities, notably based on the exascale class supercomputerBullSequana, quantum computing should also promote advances in deep learning, algorithmics and artificial intelligence for areas as various as pharmaceuticals or new materials.

For more information:Atos Quantum###

Photo caption: 6thmeeting of its Quantum Scientific Council at its headquarters in BezonsFrom left to right: Cyril Allouche, Director of Atos Quantum Lab, Atos.Philippe Duluc, SVP Big Data and Security Division, Atos.Philippe Vannier, Special advisor to the Chairman and CEO, for Science, Technology and Cybersecurity.Alain Aspect, Professor at the Institut dOptique and at the lcole Polytechnique.Sophie Proust, Chief Technology Office, Atos.Artur Ekert, Professer od quantum physics at the Institute of Mathematics, Oxford University and Singapore University.Elie Girard, CEO of Atos.Daniel Estve, Director of Research CEA Saclay, Director of Quantronics.David DiVincenzo, Professor at the Alexander von Humboldt Foundation, Director of the Institute of Theoretical Nanoelectronics at the at the Jlich Research Centre.Serge Haroche, Professor Emeritus at the Collge de France, Nobel Prize in Physics.

About AtosAtos is a global leader in digital transformation with over 110,000 employees in 73 countries and annual revenue of over 11 billion. European number one in Cloud, Cybersecurity and High-Performance Computing, the Group provides end-to-end Orchestrated Hybrid Cloud, Big Data, Business Applications and Digital Workplace solutions. The group is the Worldwide Information Technology Partner for the Olympic & Paralympic Games and operates under the brands Atos, Atos Syntel, and Unify. Atos is a SE (Societas Europaea), listed on the CAC40 Paris stock index.

The purpose of Atos is to help design the future of the information technology space. Its expertise and services support the development of knowledge, education as well as multicultural and pluralistic approaches to research that contribute to scientific and technological excellence. Across the world, the group enables its customers, employees and collaborators, and members of societies at large to live, work and develop sustainably and confidently in the information technology space.

Press contact:Laura Fau | laura.fau@atos.net | +33 6 73 64 04 18 | @laurajanefau

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Atos boosts quantum application development through the creation of the first Quantum User Group - GlobeNewswire

Natalie Wolchover at Quanta Magazine has a thoughtful but misguided essay on the inevitability of the laws of nature. She writes:

Compared to the unsolved mysteries of the universe, far less gets said about one of the most profound facts to have crystallized in physics over the past half-century: To an astonishing degree, nature is the way it is because it couldnt be any different. Theres just no freedom in the laws of physics that we have, saidDaniel Baumann, a theoretical physicist at the University of Amsterdam.

She cites Baumann to describe the incredible interlocked intricacy of physical laws:

[L]aws essentially dictate one another through their mutual consistency that nature pulls itself up by its own bootstraps. The idea turns out to explain a huge amount about the universe.

Wolchover describes how the forces of nature seem to emerge almost miraculously (the word is chosen by physicist Adam Falkowski in a comment quoted by Wolchover) from the mathematics of quantum mechanics:

[P]hysicists determine how elementary particles with different amounts of spin, or intrinsic angular momentum, can consistently behave. In doing this, they rediscover the four fundamental forces that shape the universe. Most striking is the case of a particle with two units of spin: As the Nobel Prize winner Steven Weinbergshowedin 1964, the existence of a spin-2 particle leads inevitably to general relativity Albert Einsteins theory of gravity. Einstein arrived at general relativity through abstract thoughts about falling elevators and warped space and time, but the theory also follows directly from the mathematically consistent behavior of a fundamental particle.

This beautiful simplicity of the laws of nature seem almost inevitable.

I find this inevitability of gravity [and other forces] to be one of the deepest and most inspiring facts about nature, saidLaurentiu Rodina, a theoretical physicist at the Institute of Theoretical Physics at CEA Saclay who helped tomodernize and generalizeWeinbergs proof in 2014. Namely, that nature is above all self-consistent.

What is inevitable here is not the mathematical beauty of physical law, but the circumlocutions scientists use to evade design in nature. If anything in the universe is inevitable, it is entropy and chaos. Nature falls apart, inevitably. Yet there is nothing inevitable about natures elegant harmony. Mathematical physics indeed reveals deep structure in nature, and most remarkably, that structure is beautiful, full of unexpected simplicity and poetic coincidence. Antimatter is hidden in Diracs relativistic wave equation, and oscillating bodies from galaxies to ocean waves to quarks are described quite elegantly by the simple calculus of oscillating springs. Einsteins metric tensor contains the Big Bang and black holes and an enormous but finite universe curved back in on itself.

None of this splendor and precision is inevitable, any more than a Shakespearean sonnet or the Sistine ceiling are inevitable. The mathematical subtlety of physics is the work of a living Mind of inexpressible grace and power.

The design of nature is not inevitable. Creation is from purpose, not decay. Those select scientists who are privileged to see and understand the intricate mathematical beauty of nature owe its Author a citation.

Photo: Jupiters Cloud Tops: From High to Low, by NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstadt.

Originally posted here:

Are the Laws of the Universe Inevitable? - Discovery Institute

An "action" is anything from crossing the street to making a sophisticated quantum experiment. There's no obvious reason why one type of action should be different than the other. (Credit: Mark Staff Brandl)

Recently, physicist Sean Carroll made my head spin with his explanation of the Many Worlds Interpretation of quantum mechanics. In this view, the world around us is just one version of many, many possible realities. Each time an event occurs with more than one possible outcome, reality splits into different versions. The result is that there are endless other realities containing endless other versions of you.

The idea behind the Many Worlds Interpretation originated with physicist Hugh Everett III in the 1950s. Although it sparked little serious discussion at the time, Many Worlds has recently attracted growing support among theoretical physicists as a way to make sense of what happens during measurements of quantum systems. Out of many possible outcomes, we can observe that only one actually happens. In the Everettian view, all of the other possible outcomes happen as well--they just branch off into other realities.

Not everyone finds the Many Worlds Interpretation useful or convincing, however. While I was researching this topic, I got in contact with physicist Chris Fuchs at the University of Massachusetts at Boston. He had so many outspoken things to say about quantum mechanics that I decided to share his comments in full. In particular, he offers a starkly different way of looking at quantum mechanics, called Quantum Bayesianism or QBism.

Fuchs put together a "picture book" explaining his ideas (it's the source of the images in this article). You can read about them in detail here and here. Or you can simply read on, since Fuchs is an able tour guide to his ideas about a worldview in which everyone--not just physicists--continually participates in the creation of a single reality.

Youve written critically about the Many Worlds (or Everettian) Interpretation ofquantum mechanics. What are its main shortcomings?

Its main shortcoming is simply this: The interpretation is completely contentless. I am not exaggerating or trying to be rhetorical. It is not that the interpretation is too hard to believe or too nonintuitive or too outlandish for physicists to handle the truth (rememberthe movie A Few Good Men?). It is just that the interpretation actually does not say anything whatsoever about reality. I say this despite all the fluff of the science-writing press and a few otherwise reputable physicists, like Sean Carroll, who seem to believe thisvision of the world religiously.

For me, the most important point is that the interpretation depends upon no particular oractual detail of the mathematics of quantum theory. No detail that is, exceptpossibly on an erroneous analysis of the meaning of quantum measurement introduced by John von Neumann in the 1930s, which is based on a reading of quantum states as if they are states of reality. Some interpretations of quantum theory, such as the one known as QBism, reject that analysis.

So your position is that the Many Worlds Interpretation isnt useful because it doesnt constrain our theories of physics?

Allow me to get a bit technical to try to get the point across: Would Many Worlds work if quantum mechanics were based on real vector spaces instead of on complex ones? I would say yes. Would it also work if quantum mechanics used a different product structure than the tensor product? Yes. Would it work if quantum mechanics were nonunitary, i.e., didnt obey the Schroedinger equation? Yes. And so it goes. One could even have a Many Worlds Interpretation of classical physicsas David Wallace, one of the most careful philosophers of the Many Worlds interpretation, once reluctantly admitted in a conference I attended.

The Many Worlds Interpretation just boils down to this: Whenever a coin is tossed (or any process occurs) the world splits. But who would know the difference if that were not true? What does this vision have to do with any of the details of physics?

What would you call the Many Worlds Interpretation, then? Do you regard it more as a narrative about life than a useful interpretation of how physics works?

Yep, pretty much. Heck, Jorge Louis Borges short story Garden of Forking Paths, waswritten already in 1941, whereas Hugh Everett, inventor of the Many Worlds Interpretation, wasnt on the scene until 1957. Have a look at the story. Or consider this passage from Olaf Stapledons 1937 novel Star Maker:

Whenever a creature was faced with several possible courses of action, it took them all, thereby creating many distinct temporal dimensions and distinct histories of the cosmos. Since in every evolutionary sequence of the cosmos there were many creatures and eachwas constantly faced with many possible courses, and all the possible courses were innumerable, an infinity of distinct universes exfoliated from every moment of every temporal sequence in this cosmos.

Sound familiar? These science-fiction fantasies have nothing to do with physics, and that should stand as a lesson for those who think Many Worlds is a necessary or even helpful interpretation of quantum theory.

Does a coin toss create a whole new universe? Physicist Chris Fuchs finds that idea as absurd as asking a penny what it expects from your action. (Credit: Chris Fuchs)

You also object to the idea of multiple alternate worlds on a philosophical level, correct?

Depending in no way on the details of quantum theory, the Many Worlds Interpretation hasalways seemed to me as more of a comforting religion than anything else. It takes away human responsibility for anything happening in the world in the same way that a completely fatalistic, deterministic universe does, though it purportedly saves the appearance of quantum physics by having indeterministic chance in the branches.

Here is the way I expressed what I consider the most important consideration in one of mypapers, Interviewwith a Quantum Bayesian. Id like to quote it at length, if I may:

What is the best interpretive program for making sense of quantum mechanics? [This] question [has it] completely backward. It acts as if there is this thing called quantum mechanics, displayed and available for everyone to see as they walk by itkind of like a lump of something on a sidewalk. The job of interpretation is to find the right spray to cover up any offending smells. The usual game of interpretation is that an interpretation is always something you add to the pre-existing, universally recognized quantum theory.

What has been lost sight of is that physics as a subject of thought is a dynamic interplay between storytelling and equation writing. Neither one stands alone, not even at the end of the day. But which has the more fatherly role? If you ask me, it's the storytellingAn interpretation is powerful if it gives guidance, and I would say the very best interpretation is the one whose story is so powerful it gives rise to the mathematical formalism itself (the part where non-thinking can take over). The interpretation should come first; the mathematics (i.e., the pre-existing, universally recognized thing everyone thought they were talking about before an interpretation) should be secondary

Take the nearly empty imagery of the many-worlds interpretation. Who could derive thespecific structure of complex Hilbert space out of it if one didn't already know the formalism? Most present-day philosophers of science just don't seem to get this: If an interpretation is going to be part of physics, instead of a self-indulgent ritual , it had better have some cash value for physical practice itself.

Thats a lot to take in!

Heres the way I put it a little more colorfully in another paper, QBism, the Perimeter of Quantum Bayesianism: Who could take the many-worlds idea and derive any of the structure of quantum theory out of it? This would be a bit like trying to regrow a lizard from the tip of its chopped-off tail: The Everettian conception never purported to be more than a reaction to the formalism in the first place.

Those papers build on your alternative viewwhat you call Quantum Bayesianism, orQBism. How does it interpret what happens in the world at the quantum level?

A good metaphor for quantum theory from the point of view of QBism is the Boy Scout Manual, in contrast to a Rand McNally World Atlas. The maps in the atlas are an attempt to represent all the places and terrains in the world. Of course, atlases have to be updated from time to time, but the gist of what they are meant to capture in any given edition is a kind of static, timeless entity. (That in effect is what the Everettian universal wavefunction claims to be: A catalog of what is in the world.)

The Boy Scout Manual is quite different. It is also reflective of some features of the world (or else it would have no validity), but only some features. Mostly it is meant to be a pliable guide to better living and better productivity for we who swim in the world, no matter what particular currents we encounter. Likewise, in QBism quantum states are mathematical entities that we agents who swim in the world may use for better navigation through its currents and eddies.

From this point of view, a quantum state is nothing more than a compendium of probabilityassignments: probability assignments for which consequences an agent might experience if she were to take this or that action upon her external world. Or in a less preferred language, probabilities for the outcomes of measurements. Indeed, for QBism, a quantum state is not something out in the world, as it is in the Many Worlds Interpretation. Instead it is a thought in the head of the agent using it. Different agents may even have different quantum states for the same quantum system.

One of the central mysteries of quantum mechanics is commonly described this way: Objects exist as a blurry Schrdinger wave until observed, at which point they collapse to a specific state. How do you account for that collapse?

Thats an example of language that QBism would never use. Objects exist as blurry wave? and Collapse to a specific state? Instead, in QBism, an agentan observerhassome beliefs about the consequences of her actions on a physical system (or, again in less preferred language, a measurement outcome). She takes some action on the system and notes the consequence. That might well cause her to reevaluate her beliefs about the consequences of any future action she might take on it. Those reevaluated beliefs just are the new quantum state assignment. Thats all that collapse is: It is a change of ones expectations based upon ones lived experience. And if thats all there is to it; collapse is no big deal.

It still seems weird that the observer is an integral part of a measurement.

One of the conceptual innovations of QBism was the recognition that the word measurement was always a misnomer for what was is being discussed. Before quantum mechanics, the word measurement was subliminally understood as being about looking and findingboth of them passive processes. In the 1930s, when the various no-hidden-variables theorems in quantum mechanics came up [holding that there is no hidden, deterministic process at work in quantum measurements], a number of people started thinking that looking and finding couldnt work.

Such thinking led them to the idea that measurement is all about looking and creating.Measurement is both passive and active. Things arent there before the looking, but looking somehow brings things into existence. So weird! Indeed, mystical. In contrast, QBism understands measurement as an action an agent takes on her external world with the concern being what are the consequences of the action for the agent.

What does that distinction mean, in practical terms, for understanding the way we interact with the world around us?

Viewed this way, of course measurements have a creative component in an indeterministic universe. Measurement is therefore demoted from being something mystical to being about things as mundane as walking across a busy street: It is an action I can take that has consequences for me. The only difference between such everyday events and the happenings in a quantum optics lab is whether its fruitful to apply the calculus of quantum theory for making better decisions.

Action and experience go hand in hand. To Fuchs, that connection is essential to understanding our relationship to quantum reality. (Credit: Mark Staff Brandl)

Thats the least spooky description of quantum reality I've ever seen. But how can you imagine applying quantum mechanics the universe as a whole, as quantum cosmologists attempt to do?

Youre asking, can a QBist do quantum cosmology? You ask, I assume, because I claim that QBism says that quantum mechanics is like the Boy Scout Manual: Its about making better predictions of the experiences important to me (anyone who uses it) which, by definition, involve me (the same person who uses it). Therefore, for quantum cosmology to exist at all, must it be that I am like a God who can take an action on the universe from outside it. Right?

No, of course not, just as an 11-year-old who opens the Boy Scout Manual is not a God, either. Hes just a kid doing the best he can in light of the character of reality. For QBism, measurement is simply about acting from inside the world. The measurement can be about anything from a small thing in front of me to something big, like a room-sized quantum computer, to everything that completely surrounds me. The last of these is quantum cosmology, but there is nothing special about that case.

These kinds of discussions always leave me wondering, But is it true? What kinds of tests might allow you to distinguish between the Many Worlds Interpretation and QBism, or to falsify one of them?

To the extent that both interpretations are consistent understandings of quantum theory, there can be no experimental test to discriminate between the two.With hindsight, either view can always explain any experiment that can be posed in the language of quantum mechanics.

But thats with hindsight.What about with foresight?Heres where a test between interpretations can come about, but it is purely a pragmatic test: Which interpretation promotes or suggests the most new questions, conceptual and mathematical, in physics?Which interpretation gives more guidance for solving various extant physical problems posed independently of any interpretational concern?

These are the distinguishing marks that make a difference in the real world, not in the church pews. I am proud to say that the road to QBism has led to quite a number of results in quantum information theory in just this way, whereas I really do not believe this is true for the Many Worlds Interpretation. I once asked Daniel Simon, one of the founders of quantum computation, whether Everetts interpretation of quantum mechanics aided him in finding his now-famous quantum algorithm. His response makes me laugh to this day: Everett? Who's Everett? And what is his interpretation?

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Quantum Physics is No More Mysterious Than Crossing the Street: A Conversation with Chris Fuchs - Discover Magazine

This Thursday will be Thanksgiving in the US, which we celebrate by engaging in the most American of activities: eating way too much and watching football. The more serious reason for the holiday, though, is to serve as a day of reflection on the good things in our lives that were grateful for.

For me, like many physicists, that list includes quantum mechanicsand yours should, too. Dont believe me? You think quantum physics is too strange and disturbing to count as a thing to look on with gratitude? Let me try to prove you wrong with this list of quantum phenomena without which life as we know it would be impossible.

A gingerbread couple in their bathing suits working on the perfect tan.

You should be thankful for the particle nature of light. This is the place where quantum mechanics gets its start, with a desperate trick on the part of Max Planck as he tried to find a way to derive the black-body spectrum of light emitted by a hot object like the heating element in the toaster oven you use to heat side dishes for the Thanksgiving feast. Theres a (conceptually) simple way to approach this problem, obvious to physicists circa 1900: you count up all the frequencies of light the object might emit, allocate each one an equal share of the energy available due to the heat of the object, and then youre done.

The problem is, this method fails miserably, because there are infinitely more ways to emit short wavelengths (high frequencies) than long ones, and they suck up all the energy. The simple and obvious method predicts that any hot object should spew out a vast amount of ultraviolet and x-ray light. Thats not a great feature to have in a toaster oven.

Planck fixed this ultraviolet catastrophe by assigning each frequency of light a characteristic energy, a quantum, that depends on the frequency, and saying that light can only be emitted in integer multiples of that frequency one, two, or three quanta, but never half-a-quantum, or pi quanta. For really high frequencies, the characteristic energy is greater than the share of thermal energy that would be allocated to that frequency, so no emission is possible. The short-wavelength radiation is suppressed, the ultraviolet catastrophe is avoided, and your dinner rolls brown nicely rather than being incinerated by a storm of high-frequency radiation.

bstract scientific background

You should be thankful for the wave nature of electrons. The other half of the wave-particle duality, this is one of the features that people find most disturbing about quantum physics. Its easy to think of material objects as particles with a definite position in space and time, but just plain weird to imagine material objects as wavelike disturbances spread over some region of space.

But without this wave nature, atoms as we know them would be impossible. This was first realized back in 1913 when Ernest Marsden and Hans Geiger observed alpha particles bouncing straight backward from collisions with gold atoms. Their boss, Ernest Rutherford realized that this meant that most of the mass of the gold must be concentrated in a tiny nucleus at the center of the atom, and introduced the solar-system model of an atom that kids learn in grade school these days, with negatively charged electrons orbiting a positively charged nucleus.

The problem with this model, as many people quickly pointed out, is that an electron orbiting an atom would constantly be accelerating, and accelerating charges emit radiation. An electron in Rutherfords atom, according to classical physics, should spray out an enormous blast of x-ray radiation (something of a theme, here...), losing energy in the process and spiraling in to crash into the nucleus. Thats not a recipe for the existence of stable matter.

As a solution to this problem, Niels Bohr introduced the idea of the quantum atom in 1915, with electrons existing happily in certain special orbits without emitting any radiation. He didnt have a great justification for this, but the model was undeniably an empirical success. Justification of the idea came in 1923 when Louis de Broglie suggested the idea of electrons having wave nature. A wave-like electron orbiting a nucleus would pick out a special set of states, in which an integer number of waves fit around the circumference. This idea put Erwin Schrdinger on the hunt for a wave equation for the electron, which led to his eponymous equation and one of the first complete formulations of quantum mechanics.

As a physics professor, I am obliged to note that the electron is not, in fact, a wave orbiting in a nice circular path with a little wave-like overlay the real picture is more like a fuzzy ball of probability surrounding the nucleus in one of a limited number of possible states of well-defined energy. On a conceptual level, though, you can understand the whole idea in terms of the wave nature of electrons, so when you look around and see stable atoms that arent furiously emitting x-rays, you have quantum physics to thank.

Wolfgang Pauli (1900 - 1958), winner of the 1945 Nobel Prize for Physics, receives a chocolate ... [+] cockchafer from the Lindau Casino in Bavaria, 27th June 1956. (Photo by Keystone/Hulton Archive/Getty Images)

You should be thankful for electron spin. Bohrs quantum atom, as justified by de Broglie and Schrdinger, is a great thing, but the huge variety of atoms that we see, and the chemical bonds that make complex molecules and give Thanksgiving dinner its wonderful flavor require one more quantum element. This is maybe the strangest of the quantum properties, intrinsic spin, but without it, the everyday world would be impossible.

The fundamental problem is that Bohrs idea gives us a set of allowed energy states within an atom, and works great to explain cases where you only need to worry about a single electron, but it doesnt explain how to distribute multiple electrons among these states in a more complex atom. The simplest way to do this, in fact, would be just to pile all the electrons into the lowest-energy allowed state, which would not allow for the enormous variety of elements we see in the periodic table or the complex chemistry that makes life possible.

The justification for all of that comes from two things introduced by Wolfgang Pauli: one additional quantum property, and one new rule. The new property is now called the spin of the electron, a property that can take on one of two values (typically called up and down, because physicists always default to really boring names). The new rule is that no two particles with spin can share the exact same quantum state.

This Pauli Exclusion Principle limits any of the allowed states in a quantum atom to at most two electrons (one spin-up, one spin-down). This is exactly whats required to explain the pattern of chemical properties seen in the periodic table every time you add an electron, you fill up a state, forcing later electrons to go into higher-energy states. This gives us the rich variety of chemical compounds that make life possible, and big fancy dinners enjoyable.

As if that werent enough, electron spin is also essential for the very existence of macroscopic amounts of matter. In the late 1960s, Freeman Dyson showed that a collection of arbitrary numbers of electrons and nuclei can find a stable configuration only if theyre fermions that is, particles with the right sort of spin to be subject to the Pauli Exclusion Principle. Without that property, it would always be possible for a collection of electrons and nuclei to lower their energy by packing more tightly together, imploding and releasing an enormous blast of x-rays (you knew that was coming...).

(When I was researching and writing Breakfast with Einstein (from which most of these are taken), the most striking thing from the whole process was how essential electron spin is to basically everything. Its the weirdest quantum property in a lot of ways, but absolutely essential for the existence of all the things that make us think its weird.)

Thanksgiving or Friendsgiving holiday celebration party. Flat-lay of friends feasting at ... [+] Thanksgiving Day table with turkey, pumpkin pie, roasted vegetables, fruit and rose wine, top view

So, whether you celebrate the holiday or not, when you sit down to dinner on Thursday, you have quantum physics to thank above all else. Without the particle nature of light, the wave nature of electrons, and the Pauli Exclusion Principle, the cooking, eating, and mere existence of your dinner would be impossible.

Happy Thanksgiving, everyone!

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Why You Should Give Thanks For These Three Quantum Physics Phenomena - Forbes

In a newstudy,called Experimental test of local observer independence, researchers from Heriot-Watt University in Edinburgh demonstrate via a unique experiment that two different observers are entitled to their own facts. The paper that demonstrates the lack of objectivity in quantum mechanics was published in the journalScience Advances.

What is objective reality? This is quite a philosophical question, but you dont doubt yourself when it comes to distinguishing day and night, apples and oranges, or left and right. So how surprised would you be, if you and your friend looked outside the window, and they saw day, while you definitely saw night? (To be clear, this imaginary situation isnt possible beyond the polar circle). Doesnt make any sense, right? Its dark, you see the moon and the stars, youre definitely observing night, so based on your measurements (observations), you say that its night outside, and your friend is stupid, and you want to make some new friends.

Well, quantum mechanics wont help you find new friends, but it can help you make peace with the fact that there is no objective reality. Buckle up, its quantum physics time!

Theres a fundamental principle in this mysterious science, its called quantum superposition. It states that, much like waves, any two quantum states can be added together and the result will be another valid quantum state. RememberSchrdinger's cat? The scenario presents a hypothetical cat that is simultaneously both alive and dead, so a cat is in a state of quantum superposition. However, as soon as any observer checks on the poor animal, the magical superposition state vanishes, and an observer either sees a dead or an alive cat.

The thing with a cat was always a thought experiment (Theres no evidence of Erwin Schrodingermurdering his pets in the name of science), however, there were numerous actual experiments that demonstrated the principle of superposition.

The most famous one is a double-slit experiment. It was first performed on light by Thomas Youngin early19th century. To prove its wavelike nature, scientist fired pure-wavelength light through a sheet with two slits in it, as the light passed through the slits it split in two distinct waves, after passing thought the slits these waves interfered and created an interference pattern, or a series of light and dark fringes on the screen behind the sheet. Without diffraction and interference, the light would simply make two lines on the screen.

About a century later, scientists did quite a similar experiment, but this time the experiment featured electron beam gun that fired electrons through the double-slit apparatus. If particles were sent one at a time, it resulted as a single particle appearing on the screen, as expected. Remarkably, however, an interference pattern emerged when these particles were allowed to build up one by one. The experiment, which was later conducted on whole atoms and even molecules, showed that a particle can behave as a wave, the phenomena was called wave-particle duality.

Theres one problem, though. We cant see such behavior, we can only see the result of many particles behaving this way. As soon as we peek at the particles, they stop behaving as waves and pretend to be good old particles, so elegantly described by classical physicists. Heres an explanation of the experiment performed by talented British physicist Professor Jim Al-Khalili.

But what if an observer of a quantum experiment is being observed? This thought experiment was proposed by the physicistEugene Wigner in 1961. The scenario involves an indirect observation of a quantum measurement. An observer, lets call him Bob, observes another observer, lets call her Sally, who is performing a quantum measurement on a physical system, to make it easier lets do a cat experiment again. The cat is in superposition, its either dead or alive. As soon as Sally peeks at it, the state of superposition comes to an end and the cat is being either dead or alive. Bob, however, stays out of the room, Sally doesnt let him in to check on the cat. So for Bob the whole room with Sally and the experiment is in the state of superposition, moreover, Sally and the cat are entangled, connected.

Bob can verify this superposition using a so-called interference experiment a type of quantum measurement that allows him to unravel the superposition of an entire system, confirming that two objects are entangled.

When Bob and Sally compare notes later on, Sally will insist she saw a definite outcome. And here when its all go pretty quantum. In most of the interpretations of quantum theory, the resulting statements of the two observers contradict each other.

In2018,aslav Brukner at the University of Viennademonstrated that, under certain assumptions, Wigners idea can be used to formally prove that measurements in quantum mechanics are subjective to observers. Scientist performed another thought experiment, but this time there wasnt just Bob and Sally, there was one more pair of friends watching the same quantum experiment. To get it right, we suggest to watch the video that explains the paradox.

Still,these experiments remained purely hypothetical,until now. Researchers at Heriot-Watt University in Edinburgh have actually performed the test experimentally on a small-scale quantum computer made up of three pairs of entangled photons. The first photon pair represented the quantum experiment, the other two played the outcomes of the experiment measuring the polarization of the photons inside their respective box. Outside the two boxes, two more photons remained on each side.

What, do you think, was a result of all this state-of-the-art extremely complicated nonsense? Well, to quote theresearchers who managed to bring the thought experiment to life: this result implies that quantum theory should be interpreted in an observer-dependent way. The experiment therefore demonstrates that, at least for local models of quantum mechanics, we need to rethink our notion of objectivity.

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Confirmed: There is No Objective Reality According to Quantum Mechanics - Asgardia Space News