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Category: computing – Page 381

Evidence for a chiral superconductor could bring quantum computing closer to the mainstream

The University of Tennessee’s physicists have led a scientific team that found silicon—a mainstay of the soon-to-be trillion-dollar electronics industry—can host a novel form of superconductivity that could bring rapidly emerging quantum technologies closer to industrial scale production.

The findings are reported in Nature Physics and involve electron theft, time reversal, and a little electronic ambidexterity.

Superconductors conduct electric current without resistance or energy dissipation. Their uses range from powerful electromagnets for and medical MRI devices to ultrasensitive magnetic sensors to quantum computers. Superconductivity is a spectacular display of quantum mechanics in action on a macroscopic scale. It all comes down to the electrons.

Scientists boost quantum signals while reducing noise

A certain amount of noise is inherent in any quantum system. For instance, when researchers want to read information from a quantum computer, which harnesses quantum mechanical phenomena to solve certain problems too complex for classical computers, the same quantum mechanics also imparts a minimum level of unavoidable error that limits the accuracy of the measurements.

Scientists can effectively get around this limitation by using “parametric” amplification to “squeeze” the noise—a quantum phenomenon that decreases the noise affecting one variable while increasing the noise that affects its conjugate partner. While the total amount of noise remains the same, it is effectively redistributed. Researchers can then make more accurate measurements by looking only at the lower-noise variable.

A team of researchers from MIT and elsewhere has now developed a new superconducting parametric amplifier that operates with the gain of previous narrowband squeezers while achieving quantum squeezing over much larger bandwidths. Their work is the first to demonstrate squeezing over a broad frequency bandwidth of up to 1.75 gigahertz while maintaining a high degree of squeezing (selective noise reduction). In comparison, previous microwave parametric amplifiers generally achieved bandwidths of only 100 megahertz or less.

Atom-thin walls could smash size, memory barriers in next-gen devices

For all of the unparalleled, parallel-processing, still-indistinguishable-from-magic wizardry packed into the three pounds of an adult human brain, it obeys the same rule as the other living tissue it controls: Oxygen is a must.

So it was with a touch of irony that Evgeny Tsymbal offered his explanation for a technological wonder—movable, data-covered walls mere atoms wide—that may eventually help computers behave more like a brain.

“There was unambiguous evidence that oxygen vacancies are responsible for this,” said Tsymbal, George Holmes University Professor of physics and astronomy at the University of Nebraska–Lincoln.

Why more and more physicists consider space and time to be “illusions”

O.o! If the universe is some sorta hologram then this could be a clue to our actual reality.

Last December, the Nobel Prize in Physics was awarded for experimental evidence of a quantum phenomenon that has been known for more than 80 years: entanglement. As envisioned by Albert Einstein and his collaborators in 1935, quantum objects can be mysteriously correlated even when separated by great distances. But as strange as the phenomenon may seem, why is such an old idea still worthy of the most prestigious award in physics?

Coincidentally, just weeks before the new Nobel laureates were honored in Stockholm, another team of respected scientists from Harvard, MIT, Caltech, Fermilab and Google reported that they ran a process on Google’s quantum computer that could be interpreted as a wormhole. Wormholes are tunnels through the universe that can function as a shortcut through space and time and are loved by science fiction fans, and although the tunnel realized in this latest experiment only exists in a two-dimensional toy universe, it could be a breakthrough for the future represent research at the forefront of physics.

But why does entanglement have to do with space and time? And how can it be important for future breakthroughs in physics? Properly understood, entanglement means that the universe is what philosophers call “monistic,” that is, at the most fundamental level, everything in the universe is part of a single, unified whole. It is a defining property of quantum mechanics that its underlying reality is described in terms of waves, and a monistic universe would require universal functioning. Decades ago, researchers such as Hugh Everett and Dieter Zeh showed how our everyday reality can emerge from such a universal quantum mechanical description. But it is only now that researchers such as Leonard Susskind and Sean Carroll are developing ideas as to how this hidden quantum reality could explain not only matter but also the structure of space and time.

HAL 9000: “I’m sorry Dave, I’m afraid I can’t do that”

If there’s one thing I can’t stand it’s an uppity machine.

An excerpt from the 1968 film “2001: A Space Odyssey” directed by Stanley Kubrick.

Synopsis: Mankind finds a mysterious, obviously artificial, artifact buried on the moon and, with the intelligent computer HAL, sets off on a quest, where the way the HAL 9,000 super computer malfunctions.

© Metro-Goldwyn-Mayer Inc. (MGM)

Optical Fibers Go Topological

A new design for an optical fiber borrows concepts from topology to protect light from imperfections in the fiber’s light-guiding materials or from distortions in its cross section.

Using concepts from the mathematical field of topology, researchers at the University of Bath, UK, have designed an optical fiber that can robustly propagate light, even if there are variations in the properties of its light-guiding materials or in its overall geometry [1]. The team thinks that this newfound topological protection could enable advances in optical communication and photonic quantum computing.

The concept of topology is often explained using a joke about a donut and a coffee cup. A coffee cup made of rubber can be continuously twisted and stretched—no cuts need to be made—so that it takes on the shape of a donut. Even though the object’s outline changes under this transformation, its essence remains the same—it contains one hole. Thus, the quip goes, a topologist cannot tell the difference between the two things.

N-Electron Valence Perturbation Theory with Reference Wave Functions from Quantum Computing: Application to the Relative Stability of Hydroxide Anion and Hydroxyl Radical

Quantum simulations of the hydroxide anion and hydroxyl radical are reported, employing variational quantum algorithms for near-term quantum devices. The energy of each species is calculated along the dissociation curve, to obtain information about the stability of the molecular species being investigated. It is shown that simulations restricted to valence spaces incorrectly predict the hydroxyl radical to be more stable than the hydroxide anion. Inclusion of dynamical electron correlation from nonvalence orbitals is demonstrated, through the integration of the variational quantum eigensolver and quantum subspace expansion methods in the workflow of N-electron valence perturbation theory, and shown to correctly predict the hydroxide anion to be more stable than the hydroxyl radical, provided that basis sets with diffuse orbitals are also employed.