‘Quantum go machine’ plays ancient board game using entangled photons.

A quantum-mechanical version of the ancient board game go has been  demonstrated experimentally by physicists in China. Using entangled photons, the researchers placed go pieces (called stones) in quantum superpositions to vastly increase the complexity of the game. They foresee the technology serving as the ultimate test for machine players that use ever more sophisticated artificial intelligence (AI).

Go board

In 1997, chess grandmaster Garry Kasparov was defeated by IBM’s Deep Blue computer – but having a machine defeat a go master was considered a greater challenge given the far higher number of possible board positions in go. Game enthusiasts were therefore stunned in 2016 when the world’s leading player, South Korean Lee Sedol, was beaten by a deep-learning algorithm from AI company DeepMind known as AlphaGo.

Developers of AI programs are now looking for an even greater challenges and want to beat humans at games such as poker and the tile-based game mahjong. These involve both randomness and what is known as imperfect information – the fact that one player cannot see another player’s hand.

Challenge to AI

Now, Xian-Min Jin of Shanghai Jiao Tong University and colleagues have used the counter-intuitive effects of quantum mechanics to introduced these elements into go, which is otherwise deterministic and completely transparent. A version of “quantum go” was proposed in 2016 by physicist André Ranchin, although this, like a quantum-mechanical take on chess developed at about the same time, had an educational aim. However, Jin and colleagues have devised their system to challenge game-playing AI programs.

Go involves two players alternately placing black and white stones at the vertices of 19 rows and columns drawn on a board. Each player aims to gradually enclose a greater area of the board with their stones than is enclosed by their opponent. In the process, rival pieces are captured by encirclement.

While based on a handful of simple rules, the game has complex patterns of play. That complexity is boosted even further in quantum go by using the superposition of states. Whereas classical go involves each player laying down a single stone on each move, the quantum version has them place pairs of “entangled” stones. Both pieces remain on the board until they contact a stone at an adjacent vertex, at which point a “measurement” collapses the entangled pair so that only one stone remains in play.

As each entangled pair is added to the board, the number of possible configurations is doubled. This makes it harder for each player to work out the best course of action. As in normal go, a player can capture an opponent’s stones by placing their own pieces on all neighbouring vertices. But those pieces must be classical. If any are in an entangled state, the player will generally not know before they carry out the respective measurements which of the two stones in each pair will remain on the board, and therefore whether or not they will succeed in encircling their opponent.

Imperfect information

Jin and colleagues explain that the measuring process can be tuned by engineering the quantum entanglement. If the two stones in each pair are maximally entangled, then the outcome of the measurement will be completely random. Otherwise, one stone will have a higher probability of remaining on the board than the other. With these probabilities known only to the person positioning the stones, the game loses some of its randomness but gains an element of imperfect information.

A quantum boost for machine learning

The Chinese researchers put these ideas into practice by generating pairs of photons entangled in term of their polarizations, then sending the photons through beam splitters and measuring coincidence counts in four single-photon detectors. With one set of outputs corresponding to a “0” and another to “1”, they were able to generate and then store a random series of 0s and 1s. This series was used to assign collapse probabilities to each half of a pair of virtual stones positioned at random vertices on a virtual go board by Internet bots.

By continuously generating entangled photons and storing the measurement results, the team produced about 100 million collapse probabilities in an hour. That, they point out, is more than enough for any normal game of go. Indeed, it is enough data to support a game with 100 million moves played on a board with 10,000 rows and columns. Analysing the distribution of 1s and 0s in time, they were also able to confirm that there was no significant correlation between one data point and the next. The data, in other words, were indeed random.

Clearly random

Jin points out that some classical physical processes could also generate the random series of 1s and 0s (as opposed to pseudo-random series produced by computers). But he says that these processes are not easy to manipulate. The randomness that his team generated, he argues, is in contrast “much clearer due to the inherent nature of quantum mechanics”.

The team points out that the exact relation between the complexity and difficulty of quantum go “is still an open question”, but argue its beauty lies in being able to cover a wide range of difficulties rather than just one. By increasing the size of the virtual go board and tuning the entanglement, they claim it should be possible to match the difficulty even of those games that hide the most information, such as mahjong. As such, they say, quantum go could provide “a versatile and promising platform for testing new algorithms for artificial intelligence”.

from: https://physicsworld.com/a/quantum-go-machine-plays-ancient-board-game-using-entangled-photons/

New material for quantum computing discovered out of the blue

A common blue pigment used in the £5 note could have an important role to play in the development of a quantum computer, according to a paper published in the journal Nature.

Blue quantum

Phthalocyanine thin film on a flexible plastic substrate, showing the coexistence of long-lived “0” and “1” qubits on the copper spin. The molecules form a regular array together with the metal-free analogues, and the background represents the lattice fringes of the molecular crystals obtained by transmission electron microscopy.

The pigment, copper phthalocyanine (CuPc), which is similar to the light harvesting section of the chlorophyll molecule, is a low-cost organic semiconductor that is found in many household products. Crucially, it can be processed into a thin film that can be readily used for device fabrication, a significant advantage over similar materials that have been studied previously.

Now, researchers from the London Centre for Nanotechnology and the University of British Columbia have shown that the electrons in CuPc can remain in ‘superposition’ – an intrinsically quantum effect where the electron exists in two states at once – for surprisingly long times, showing this simple dye molecule has potential as a medium for quantum technologies.

The development of quantum computing requires precise control of tiny individual “qubits”, the quantum analogs of the classical binary bits, ‘0’ and ‘1’, which underpin all of our computation and communications technologies today. What distinguishes the “qubits” from classical bits is their ability to exist in superposition states.

The decay time of such superpositions tells us how useful a candidate qubit could be in quantum technologies. If this time is long, quantum data storage, manipulation and transmission become possible.

Our research shows that a common blue dye has more potential for quantum computing than many of the more exotic molecules that have been considered previously.

Dr Marc Warner

Lead author Marc Warner from the London Centre for Nanotechnology, said: “In theory, a quantum computer can easily solve problems that a normal, classical, computer would not be able to answer in the lifetime of the universe. We just don’t know how to build one yet.

“Our research shows that a common blue dye has more potential for quantum computing than many of the more exotic molecules that have been considered previously.”

CuPc possesses many other attributes that could exploit the spin of electrons, rather than their charge, to store and process information which are highly desirable in a more conventional quantum technology. For example, the pigment strongly absorbs visible light and is easy to modify chemically and physically, so its magnetic and electrical properties can be controlled.

Dr Warner added: “The properties of copper phthalocyanine make it of interest for the emerging field of quantum engineering, which seeks to exploit the quantum properties of matter to perform tasks like information processing or sensing more effectively than has ever been possible.”

Structure and morphology of phthalocyanine films. a) Structure of a metal phthalocyanine (MPc). b) Picture of a 2.5 cm 2 CuPc film deposited onto a 100 cm 2 Kapton sheet. c) Structure of PTCDA, used as a templating layer. Atomic force microscopy images of d) a 60 nm CuPc film deposited by OMBD at room temperature on Kapton, leading to a-phase crystallites; e) a b-polymorph obtained after annealing for 2 h at 320 °C; and f) a templated film deposited at room temperature onto a PTCDA first layer. Schematics of the unit cells of g) a-CuPc, h) b-CuPc, and i) templated CuPc, where f is the angle between the stacking axis and the molecular planes.

Structure and morphology of phthalocyanine films. a) Structure of a metal phthalocyanine (MPc). b) Picture of a 2.5 cm 2 CuPc film deposited onto a 100 cm 2 Kapton sheet. c) Structure of PTCDA, used as a templating layer. Atomic force microscopy images of d) a 60 nm CuPc film deposited by OMBD at room temperature on Kapton, leading to a-phase crystallites; e) a b-polymorph obtained after annealing for 2 h at 320 °C; and f) a templated film deposited at room temperature onto a PTCDA first layer. Schematics of the unit cells of g) a-CuPc, h) b-CuPc, and i) templated CuPc, where f is the angle between the stacking axis and the molecular planes.

sources:
https://www.ucl.ac.uk/news/2013/oct/new-material-quantum-computing-discovered-out-blue
https://www.researchgate.net/publication/1922170_Molecular_Thin_Films_a_New_Type_of_Magnetic_Switch
https://www.nature.com/articles/s41598-017-13271-w

Elegant mathematical model universes

Are elegant mathematical models of the universe more important than empirical observed modelling of our solar system, galaxies and universe?

It’s a beautiful theory: the standard model of cosmology describes the universe using just six parameters. But it is also strange. The model predicts that dark matter and dark energy – two mysterious entities that have never been detected – make up 95% of the universe, leaving only 5% composed of the ordinary matter so essential to our existence.

Elegant maths model universes

The idea that fundamental particles are actually tiny bits of vibrating string was taking off, and by the mid-1980s, string theory had lassoed the imaginations of many leading physicists. The idea is simple: just as a vibrating violin string gives rise to different notes, each string’s vibration foretells a particle’s mass and behavior. The mathematical beauty was irresistible and led to a swell of enthusiasm for string theory as a way to explain not only particles but the universe itself.
Gravity is mathematically relatable to dynamics of subatomic particles | phys.org

It’s embarrassing, but astrophysicists are the first to admit it. Our best theoretical model can only explain 5% of the universe. The remaining 95% is famously made up almost entirely of invisible, unknown material dubbed dark energy and dark matter.
Bizarre ‘dark fluid’ with negative mass could dominate the universe | phys.org

Mathematical universe hypothesis

Our external physical reality is a mathematical structure. That is, the physical universe is not merely described by mathematics, but is mathematics (specifically, a mathematical structure). Mathematical existence equals physical existence, and all structures that exist mathematically exist physically as well. Observers, including humans, are self-aware substructures (SASs). In any mathematical structure complex enough to contain such substructures, they will subjectively perceive themselves as existing in a physically ‘real’ world.

The theory can be considered a form of Pythagoreanism or Platonism in that it proposes the existence of mathematical entities; a form of mathematical monism in that it denies that anything exists except mathematical objects; and a formal expression of ontic structural realism.

Tegmark claims that the hypothesis has no free parameters and is not observationally ruled out. Thus, he reasons, it is preferred over other theories-of-everything by Occam’s Razor. Tegmark also considers augmenting the MUH with a second assumption, the computable universe hypothesis (CUH), which says that the mathematical structure that is our external physical reality is defined by computable functions.
Mathematical universe hypothesis | wikipedia

Dark fluid with negative mass and negative gravity

No matter how physically and logically preposterous a proposed universe construct is, to the man in the street, as long as there are no obvious peer reviewed alternatives, then mathematical scientists will at least not be able to be rule it out.
In an essay for The Conversation, Farnes concedes that the negative mass theory could be incorrect – but also expresses hope that, if it’s borne out by future observations, it could provide a new model for explaining the mysteries of the cosmos.

Despite these efforts, a negative mass cosmology could be wrong, he wrote. The theory seems to provide answers to so many currently open questions that scientists will — quite rightly — be rather suspicious. However, it is often the out-of-the-box ideas that provide answers to longstanding problems. The strong accumulating evidence has now grown to the point that we must consider this unusual possibility.
An Oxford Scientist May Have Solved the Mystery of Dark Matter

You can mathematically propose anything and as long as it is not currently falsifiable, it has to be considered as an alternative framework. The more elegant mathematics it uses to possibly explain things, the more popular it might be with those who live in alternative maths universes.

In this new theory, the negative mass particles are continuously created, so the particles are always replenished as the universe expands, he explained. In this new approach, these continuously – created negative masses seem to be identical to dark energy. By combining negative mass and matter creation, dark matter and dark energy can be unified into one single substance – a dark fluid.

One of the reasons we know dark matter exists is its gravitational influence over galaxies. Observations show galaxies are spinning far faster than they should—so fast they should be torn apart. Dark matter, it appears, is helping to hold them together. To test his theory, Farnes created a 3D computer model of his dark fluid to see if it would hold a galaxy together. And it did. “The new model has been tested using a simulation of the universe within a computer, and seems to naturally generate dark matter halos around ‘positive mass’ galaxies. This is a direct observational expectation of dark matter, and so seems to indicate that the model has promise. However, there is still much work to be done to test this idea further.

Farnes says are limitations to the research: The current model provides no explanation at all for the particle physics that may make negative masses possible, he said. This is currently half of all known physics that is not being included into my model!

However, he also says the nature of mass is poorly understood in particle physics, so ideas of negative mass could be incorporated to explain other scientific conundrums.

Alex Murphy, Professor of Nuclear & Particle Astrophysics at the U.K.’s University of Edinburgh, who was not involved in the study, said the findings are interesting: “It’s one of many efforts trying to provide answers to deeply troubling issues with our understanding of the contents of the universe,” he told Newsweek. “The key result is that if there is the right amount of negative mass matter in the universe, then one can explain the observed motions and distributions of galaxies that otherwise require dark matter and dark energy to exist. That is quite elegant.”
most of the universe is missing — a ‘dark fluid’ with negative mass could explain why | Newsweek

The creator of the field of cosmology, Albert Einstein, did – along with other scientists including Stephen Hawking – consider negative masses. In fact, in 1918 Einstein even wrote that his theory of general relativity may have to be modified to include them.

Despite these efforts, a negative mass cosmology could be wrong. The theory seems to provide answers to so many currently open questions that scientists will – quite rightly – be rather suspicious. However, it is often the out-of-the-box ideas that provide answers to longstanding problems. The strong accumulating evidence has now grown to the point that we must consider this unusual possibility.
Bizarre ‘dark fluid’ with negative mass could dominate the universe | The Conversation

Non Euclidean space-time

According to Albert Einstein’s theory of special relativity, instantaneous action at a distance violates the relativistic upper limit on speed of propagation of information. If one of the interacting objects were to suddenly be displaced from its position, the other object would feel its influence instantaneously, meaning information had been transmitted faster than the speed of light.

One of the conditions that a relativistic theory of gravitation must meet is that gravity is mediated with a speed that does not exceed c, the speed of light in a vacuum. From the previous success of electrodynamics, it was foreseeable that the relativistic theory of gravitation would have to use the concept of a field, or something similar.

This has been achieved by Einstein’s theory of general relativity, in which gravitational interaction is mediated by deformation of space-time geometry. Matter warps the geometry of space-time, and these effects are – as with electric and magnetic fields – propagated at the speed of light. Thus, in the presence of matter, space-time becomes non-Euclidean, resolving the apparent conflict between Newton’s proof of the conservation of angular momentum and Einstein’s theory of special relativity.
Einstein – Action at a distance | wikipedia

Dark Matter Hurricanes

But it just may cause some local spikes in dark matter, which would help researchers hunting dark matter actually find the stuff, the researchers wrote.

That’s because all galaxies, but especially dwarf galaxies, are held together by dark matter, physicists believe. So, the galaxy that was torn to shreds birthing the S1 stream likely dumped a bunch of dark matter into the stream’s path.

The problem is, no existing dark matter-detection devices have actually worked, in part because they’ve all been designed based on educated guesses as to what dark matter really is. (Scientists have very good reason to believe dark matter exists but are still guessing about its composition.)
Do Not Fear the Dark Matter Hurricane (The Dark Matter Hurricane Is Good)

Strings of gravity particles

The key insight is that gravity, the force that brings baseballs back to Earth and governs the growth of black holes, is mathematically relatable to the peculiar antics of the subatomic particles that make up all the matter around us.

This revelation allows scientists to use one branch of physics to understand other seemingly unrelated areas of physics. So far, this concept has been applied to topics ranging from why black holes run a temperature to how a butterfly’s beating wings can cause a storm on the other side of the world.

Meanwhile, the idea that fundamental particles are actually tiny bits of vibrating string was taking off, and by the mid-1980s, “string theory” had lassoed the imaginations of many leading physicists. The idea is simple: just as a vibrating violin string gives rise to different notes, each string’s vibration foretells a particle’s mass and behavior. The mathematical beauty was irresistible and led to a swell of enthusiasm for string theory as a way to explain not only particles but the universe itself…

The breakthrough in the late 1990s was that mathematical calculations of the edge, or boundary, of this anti-de Sitter space can be applied to problems involving quantum behaviors of subatomic particles described by a mathematical relationship called conformal field theory (CFT). This relationship provides the link, which Polyakov had glimpsed earlier, between the theory of particles in four space-time dimensions and string theory in five dimensions. The relationship now goes by several names that relate gravity to particles, but most researchers call it the AdS/CFT (pronounced A-D-S-C-F-T) correspondence.

Copy from source: http://www.everythingselectric.com/eie-73/
Gravity is mathematically relatable to dynamics of subatomic particles | www.phys.org