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Primeur weekly 2017-12-04

Quantum computing

Simulating physics ...

Key component for quantum computing invented ...

Quantum-emitting answer might lie in the solution ...

Quantum systems correct themselves ...

NCSA SPIN intern Daniel Johnson published in Classical and Quantum Gravity ...

Focus on Europe

9th Irish Supercomputer List published ...

Gap between research and industry HPC in Ireland widens ...

SURFsara extends its status as Intel Parallel Computing Center for 2018 ...

EXDCI issues Call for Workshops for the European HPC Summit Week 2018 ...

Hardware

Supermicro introduces next-generation storage form factor with new Intel "Ruler" all-flash NVMe 1U server and JBOF ...

New director named at Los Alamos National Laboratory ...

AccelStor empowers all-flash array to advance genomics data analysis ...

New Storage 2020 report outlines vision for future HPC storage ...

Loci adds William Schrader, former PSINet Inc. CEO, to Advisory Board ...

Shantenu Jha named Chair of Brookhaven Lab's Center for Data-Driven Discovery ...

Applications

ORNL-designed algorithm leverages Titan to create high-performing deep neural networks ...

Drought-resistant plant genes could accelerate evolution of water-use efficient crops ...

HPE partners with Stephen Hawking's COSMOS Research Group and the Cambridge Faculty of Mathematics ...

Monopole current offers way to control magnets ...

70Gb/s optical intra-connects in data centers based on band-limited devices ...

Lobachevsky University scientists in search of fast algorithms for discrete optimization ...

High-Performance Computing cuts particle collision data prep time ...

TOP500

High performance computer MOGON II at the Johannes Gutenberg-Universität Mainz among the 100 fastest supercomputers in the world ...

The Cloud

HPE unveils industryis first SaaS-based multi-Cloud management solution for on-premises and public Clouds ...

AccelStor revs up NeoSapphire all-flash array portfolio for next generation Cloud application ...

Simulating physics


The computational processing power of quantum bits (qubits) is poised to have profound impacts on the diverse fields of science and engineering. Using nine superconducting qubits, researchers at Google and the Centre for Quantum Technologies in Singapore were able to simulate the intricate energy spectrum predicted for 2D electrons in a magnetic field, the Hofstadter Butterfly. This graphic is based on experimental data. Photo Credit: Visual Science and Google Inc.
4 Dec 2017 Santa Barbara - When does a metal stop being metallic? When do atoms start breaking the rules of chemistry as we know them? To the naked eye, and at room temperatures, such quantum phase transitions are not visible and not allowed. But when you cool certain materials to just shy of absolute zero and observe them at the atomic level these curious physical phenomena present interesting and peculiar behaviours.

In the words of Pedram Roushan, a researcher in Google-affiliated UC Santa Barbara (UCSB) physics professor John Martinis's group, "Understanding quantum phases is still one of physics' unsolved mysteries."

Why? For one, at near-zero temperatures, these behaviours aren't influenced by changes in heat levels - unlike the gas-liquid-solid transitions we see every day. Another reason: the sheer complexity of the interactions between various particles in an environment governed by quantum mechanics, in which a particle also is a wave, multiple particles can correlate over distance and occupy several states simultaneously. The calculations are beyond the ability of any conventional computer.

However, the Google/Martinis Group, teaming up with researchers from the Centre for Quantum Technologies at National University of Singapore (NUS), has devised a method for investigating quantum phases of matter. To do so they are using a chain of nine superconducting quantum bits (qubits) and spectroscopy, which measures light, to study the energy levels of a system.

Their work, "Spectral signatures of many-body localization with interacting photons", appears in the journalScience.

"A quantum computer can do any computation that you ask for", Pedram Roushan stated. For this demonstration, the researchers chose to tackle the issue of many-body localization, a situation in which the many interacting bodies - in this case, electrons - lose their ability to propagate through a medium. In metals, which are superconductors, this would result in the loss of one of their defining aspects and turn them into insulators.

"This was known after Philip Anderson predicted it in the late 1950s", Pedram Roushan stated of the phenomenon known as Anderson localization, which occurs when there is enough disorder (randomness) in a system to interrupt the movement of electrons. In solid metals, identical atoms are arranged in a "lattice" of (ideally) regularly repeating uniform structures that allow the particles to move with minimal energy spent.

"But say you start taking atoms out of the lattice and replace them with some foreign atoms", he explained. "It becomes a very jagged landscape and electron conduction cannot happen." Replicate this in a system, and you have a many-body localization situation.

Enter spectroscopy, or the use of light to assess the composition of a material, be it a distant planet or the soft tissues of our bodies. The electrons of different types of atoms absorb and emit light (photons) at different wavelengths depending on the atom’s allowable and discrete energy levels, giving each material a unique spectral signature.

"It has been predicted in the last 10 years that there would be a spectral signature for a system with metallic properties - where there is conduction - and systems that become insulators, where there is no conduction", Pedram Roushan stated.

In a process akin to musicians striking a tuning fork and listening for the main note, the researchers "hit" their nine-qubit system with photons and waited as the system evolved to reveal its fundamental frequencies.

"One of the most fundamental postulates of quantum mechanics states that if a system starts in a non-eigenstate, it will evolve in time according to the Schrodinger equation", stated Dimitris Angelakis, who specializes in quantum optics and many-body physics at NUS. A system out of equilibrium, he added, is expected to eventually find some kind of equilibrium ("thermalize") relative to the inherent characteristics of the system.

On the other hand, many-body localization, Dimitris Angelakis explained, is a situation where energy and information does not diffuse over time. The spectral signature of an evolving, thermalizing system, according to the researchers, would be different from one experiencing many-body localization.

To demonstrate and benchmark their highly tunable nine qubit platform, the researchers caught a butterfly. That is, they used their system to simulate the complicated motion of electrons under a magnetic field, as predicted by physicist Douglas Hofstadter in 1976.

Having demonstrated their control over the system, they then introduced two photons, while drastically increasing the system's complexity and also programming increasing levels of irregularities and disorder.

"By putting two photons in you had a problem of 45 energy levels and these 45 levels would interact and push each other out of the way", Pedram Roushan stated.

Several photonic strikes in different places yielded multiple sets of frequencies.

"Kind of like the vibrations generated in a guitar string or a bell or a drum when struck", Dimitris Angelakis stated. "The total sound generated is a superposition of all the basic harmonics of the instrument with different contributions/weights, depending on the initial state/strike."

In music, the musicians would then use the dominant notes, or frequencies, as guides. So, too, did the researchers with the spectral vibrations generated by each hit of the qubit system, which they then transformed into their component frequencies to determine what energy signatures emerged as a result of increasing levels of disorder.

In a low-disorder system, Pedram Roushan said, energy levels remained discrete, repelling each other, and were evenly distributed across the chain. But as disorder increased, the energy levels become uncorrelated and independent of each other.

With their embryonic quantum computer of nine qubits, the researchers are only scratching the surface of what a full-sized quantum computer could do. However, according to co-author and UCSB researcher Charles Neill, this development proves that problems that have been out of the reach of current computational power - such as the multitudes of simultaneous interactions between quantum particles under varying levels of disorder - are now possible to approach.

"It touches on really fundamental physics", he stated, "and we can really start to embed lots of different physical problems."
Source: University of California at Santa Barbara

Back to Table of contents

Primeur weekly 2017-12-04

Quantum computing

Simulating physics ...

Key component for quantum computing invented ...

Quantum-emitting answer might lie in the solution ...

Quantum systems correct themselves ...

NCSA SPIN intern Daniel Johnson published in Classical and Quantum Gravity ...

Focus on Europe

9th Irish Supercomputer List published ...

Gap between research and industry HPC in Ireland widens ...

SURFsara extends its status as Intel Parallel Computing Center for 2018 ...

EXDCI issues Call for Workshops for the European HPC Summit Week 2018 ...

Hardware

Supermicro introduces next-generation storage form factor with new Intel "Ruler" all-flash NVMe 1U server and JBOF ...

New director named at Los Alamos National Laboratory ...

AccelStor empowers all-flash array to advance genomics data analysis ...

New Storage 2020 report outlines vision for future HPC storage ...

Loci adds William Schrader, former PSINet Inc. CEO, to Advisory Board ...

Shantenu Jha named Chair of Brookhaven Lab's Center for Data-Driven Discovery ...

Applications

ORNL-designed algorithm leverages Titan to create high-performing deep neural networks ...

Drought-resistant plant genes could accelerate evolution of water-use efficient crops ...

HPE partners with Stephen Hawking's COSMOS Research Group and the Cambridge Faculty of Mathematics ...

Monopole current offers way to control magnets ...

70Gb/s optical intra-connects in data centers based on band-limited devices ...

Lobachevsky University scientists in search of fast algorithms for discrete optimization ...

High-Performance Computing cuts particle collision data prep time ...

TOP500

High performance computer MOGON II at the Johannes Gutenberg-Universität Mainz among the 100 fastest supercomputers in the world ...

The Cloud

HPE unveils industryis first SaaS-based multi-Cloud management solution for on-premises and public Clouds ...

AccelStor revs up NeoSapphire all-flash array portfolio for next generation Cloud application ...