Lifeboat Foundation

Why send a message back in time, but lock it so that no one can ever read the contents? Because it may be the key to solving currently intractable problems. That’s the claim of an international collaboration who have just published a paper in npj Quantum Information.

It turns out that an unopened message can be exceedingly useful. This is true if the experimenter entangles the message with some other system in the laboratory before sending it. Entanglement, a strange effect only possible in the realm of quantum physics, creates correlations between the time-travelling message and the laboratory system. These correlations can fuel a quantum computation.

Around ten years ago researcher Dave Bacon, now at Google, showed that a time-travelling quantum computer could quickly solve a group of problems, known as NP-complete, which mathematicians have lumped together as being hard.

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Why send a message back in time, but lock it so that no one can ever read the contents? Because it may be the key to solving currently intractable problems. That’s the claim of an international collaboration who have just published a paper in npj Quantum Information.

It turns out that an unopened message can be exceedingly useful. This is true if the experimenter entangles the message with some other system in the laboratory before sending it. Entanglement, a strange effect only possible in the realm of quantum physics, creates correlations between the time-travelling message and the laboratory system. These correlations can fuel a quantum computation.

Around ten years ago researcher Dave Bacon, now at Google, showed that a time-travelling quantum computer could quickly solve a group of problems, known as NP-complete, which mathematicians have lumped together as being hard.

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Where are the limits of human technology? And can we somehow avoid them? This is where quantum computers become very interesting.

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A mathematical problem underlying fundamental questions in particle and quantum physics is provably unsolvable, according to scientists at UCL, Universidad Complutense de Madrid — ICMAT and Technical University of Munich.

It is the first major problem in physics for which such a fundamental limitation could be proven. The findings are important because they show that even a perfect and complete description of the microscopic properties of a material is not enough to predict its macroscopic behaviour.

A small spectral gap — the energy needed to transfer an electron from a low-energy state to an excited state — is the central property of semiconductors. In a similar way, the spectral gap plays an important role for many other materials. When this energy becomes very small, i.e. the spectral gap closes, it becomes possible for the material to transition to a completely different state. An example of this is when a material becomes superconducting.

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Google appears to be more confident about the technical capabilities of its D-Wave 2X quantum computer, which it operates alongside NASA at the U.S. space agency’s Ames Research Center in Mountain View, California.

D-Wave’s machines are the closest thing we have today to quantum computing, which work with quantum bits, or qubits — each of which can be zero or one or both — instead of more conventional bits. The superposition of these qubits can allow great numbers of computations to be performed simultaneously, making a quantum computer highly desirable for certain types of processes.

In two tests, the Google Quantum Artificial Intelligence (AI) Lab today announced that it has found the D-Wave machine to be considerably faster than simulated annealing — a simulation of quantum computation on a classical computer chip.

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(Image: IBM)

The race to build a full-blown quantum computer is heating up. Tech giant IBM has been working on error-correcting techniques for quantum hardware, and has now won funding from the US Intelligence Advanced Research Projects Activity (IARPA) to take it to the next level.

Quantum computers promise to vastly outperform normal PCs on certain problems. But efforts to build them have been hampered by the fragility of quantum bits, or qubits, as the systems used to store them are easily affected by heat and electromagnetic radiation. IBM is one of a number of companies and research teams developing error-correcting techniques to iron out these instabilities.

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Governments and leading computing companies such as Microsoft, IBM, and Google are trying to develop what are called quantum computers because using the weirdness of quantum mechanics to represent data should unlock immense data-crunching powers. Computing giants believe quantum computers could make their artificial-intelligence software much more powerful and unlock scientific leaps in areas like materials science. NASA hopes quantum computers could help schedule rocket launches and simulate future missions and spacecraft. “It is a truly disruptive technology that could change how we do everything,” said Deepak Biswas, director of exploration technology at NASA’s Ames Research Center in Mountain View, California.

Biswas spoke at a media briefing at the research center about the agency’s work with Google on a machine they bought in 2013 from Canadian startup D-Wave systems, which is marketed as “the world’s first commercial quantum computer.” The computer is installed at NASA’s Ames Research Center in Mountain View, California, and operates on data using a superconducting chip called a quantum annealer. A quantum annealer is hard-coded with an algorithm suited to what are called “optimization problems,” which are common in machine-learning and artificial-intelligence software.

However, D-Wave’s chips are controversial among quantum physicists. Researchers inside and outside the company have been unable to conclusively prove that the devices can tap into quantum physics to beat out conventional computers.

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(Phys.org)—In a new study, physicists at Penn State University have for the first time proposed a way to test a little-understood form of quantum mechanics called nonassociative quantum mechanics. So far, all other tests of quantum mechanics have dealt with the associative form, so the new test provides a way to explore this relatively obscure part of the theory.

“Nonassociative quantum mechanics has been of mathematical interest for some time (and has recently shown up in certain models of String Theory), but it has been impossible to obtain a physical understanding,” coauthor Martin Bojowald at Penn State told Phys.org. “We have developed methods which allow us to do just that, and found a first application with a characteristic and instructive result. One of the features that makes this setting interesting is that much of the usual mathematical toolkit of quantum mechanics is inapplicable.”

Standard quantum mechanics is considered associative because mathematically it obeys the associative property. One of the fundamental concepts of standard quantum mechanics is the wave function, which gives the probability of finding a quantum system in a particular state. (The wave function is what determines the likelihood of Schrödinger’s cat being dead or alive, before the box is opened.) Mathematically, wave functions are vectors, and the mathematical operations involving vectors and the operators that act on them always obey the associative property (AB)C=A(BC), where the way that the parentheses are set doesn’t matter.

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The extremely sensitive quantum-spacetime-measuring tool will serve as a template for continuing scientific exploration.

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