Lifeboat Foundation

Tl;dr: Experimentalists are bringing increasingly massive systems into quantum states. They are now close to masses where they might be able to just measure what happens to the gravitational field.

Quantum effects of gravity are weak, so weak they are widely believed to not be measurable at all. Freeman Dyson indeed is fond of saying that a theory of quantum gravity is entirely unnecessary, arguing that we could never observe its effects anyway. Theorists of course disagree, and not just because they’re being paid to figure out the very theory Dyson deems unnecessary. Measurable or not, they search for a quantized version of gravity because the existing description of nature is not merely incomplete – it is far worse, it contains internal contradictions, meaning we know it is wrong.

Take the century-old double-slit experiment, the prime example for quantum behavior. A single electron that goes through the double-slit is able to interact with itself, as if it went through both slits at once. Its behavior is like that of a wave which overlaps with itself after passing an obstacle. And yet, when you measure the electron after it went through the slit it makes a dot on a screen, like a particle would. The wave-like behavior again shows up if one measures the distribution of many electrons that passed the slit. This and many other experiments demonstrate that the electron is neither a particle nor a wave – it is described by a wave-function from which we obtain a probability distribution, a formulation that is the core of quantum mechanics.

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A team of physicists has proposed a way of teleporting energy over long distances. The technique, which is purely theoretical at this point, takes advantage of the strange quantum phenomenon of entanglement where two particles share the same existence.

The researchers, who work out of Tohoku University in Japan, and led by Masahiro Hotta,describe their proposal in the latest edition of Physical Review A. Their system exploits properties of squeezed light or vacuum states that should allow for the teleportation of information about an energy state. In turn, this teleported quantum energy could be made useable.

Unlike teleportation schemes as portrayed in Star Trek or The Fly, this type of teleportation describes entanglement experiments in which two entangled particles are joined despite no apparent connection between them. When a change happens to one particle, the same change happens to the other. Hence, the impression of teleportation. Physicists have conducted experiments using light, matter, and now, energy.

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A team of scientists from the University of Chicago and the Pennsylvania State University have accidentally discovered a new way of using light to draw and erase quantum-mechanical circuits in a unique class of materials called topological insulators.

In contrast to using advanced nanofabrication facilities based on chemical processing of materials, this flexible technique allows for rewritable ‘optical fabrication’ of devices. This finding is likely to spawn new developments in emerging technologies such as low-power electronics based on the spin of electrons or ultrafast quantum computers.

The research is published today in the American Association for the Advancement of Science’s new online journal Science Advances, where it is featured on the journal’s front page.

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What can skyrmions do for you? These ghostly quantum rings, heretofore glimpsed only under extreme laboratory conditions, just might be the basis for a new type of computer memory that never loses its grip on the data it stores.

Now, thanks to a research team including scientists from the National Institute of Standards and Technology (NIST), the exotic ring-shaped magnetic effects have been coaxed out of the physicist’s deepfreeze with a straightforward method that creates magnetic skyrmions under ambient room conditions. The achievement brings skyrmions a step closer for use in real-world data storage as well as other novel magnetic and electronic technologies.

If you have a passing familiarity with particle physics, you might expect skyrmions to be particles; after all, they sound a lot like fermions, a class of particles that includes protons and neutrons. But skyrmions are not fundamental pieces of matter (not even of yogurt); they are effects named after the physicist who proposed them. Until just recently, magnetic skyrmions had only been seen at very low temperatures and under powerful magnetic fields.

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Many researchers find these ideas irresistible. Within the last few years, physicists in seemingly unrelated specialties have converged on this confluence of entanglement, space and wormholes. Scientists who once focused on building error-resistant quantum computers are now pondering whether the universe itself is a vast quantum computer that safely encodes spacetime in an elaborate web of entanglement. “It’s amazing how things have been progressing,” says Van Raamsdonk, of the University of British Columbia in Vancouver.

Physicists have high hopes for where this entanglement-spacetime connection will lead them. General relativity brilliantly describes how spacetime works; this new research may reveal where spacetime comes from and what it looks like at the small scales governed by quantum mechanics. Entanglement could be the secret ingredient that unifies these supposedly incompatible views into a theory of quantum gravity, enabling physicists to understand conditions inside black holes and in the very first moments after the Big Bang.

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“Thinking in a quantum-like way lets people confront complex questions.”

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The significant advance, by a team at the University of New South Wales (UNSW) in Sydney appears today in the international journal Nature.

“What we have is a game changer,” said team leader Andrew Dzurak, Scientia Professor and Director of the Australian National Fabrication Facility at UNSW.

“We’ve demonstrated a two-qubit logic gate — the central building block of a quantum computer — and, significantly, done it in silicon. Because we use essentially the same device technology as existing computer chips, we believe it will be much easier to manufacture a full-scale processor chip than for any of the leading designs, which rely on more exotic technologies.

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For decades, researchers have been trying to build a computer that harnesses the enormous potential of quantum mechanics. Now engineers from the University of New South Wales (UNSW) in Australia have overcome the final hurdle, by creating a quantum logic gate in silicon — the same material that today’s computer chips are made from.

The newly developed device allows two quantum bits — or qubits — to communicate and perform calculations together, which is a crucial requirement for quantum computers. Even better, the researchers have also worked out how to scale the technology up to millions of qubits, which means they now have the ability to build the world’s first quantum processor chip and, eventually, the first silicon-based quantum computer.

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A Game Changer in Quantum Computing:
The ingredients for superfast computers could be nearly in place. For the first time, researchers have demonstrated that two silicon transistors acting as quantum bits can perform a tiny calculation.

The advance represents the final physical component needed to realise the promise of super-powerful silicon quantum computers, which harness the science of the very small — the strange behaviour of subatomic particles — to solve computing challenges that are beyond the reach of even today’s fastest supercomputers. Potentially transforming fields like encryption and the search for new pharmaceuticals.

Continue reading “A quantum logic gate in silicon built for the for the first time (w/video)” »