Back to Table of contents

Primeur weekly 2018-07-30

Focus

Verne Global turns clever SME ideas into Cloud compute reality with hpcDIRECT in free-cooled Icelandic data centres ...

Opin Kerfi goes big with HPC cluster leasing and co-location in Iceland offering free cooling and purity of air ...

Quantum computing

World-first quantum computer simulation of chemical bonds using trapped ions ...

Demon in the details of quantum thermodynamics ...

Tuning into quantum: Scientists unlock signal frequency control of precision atom qubits ...

Hardware

BrainChip to showcase neuromorphic computing solutions at MPSoC ...

BrainChip unveils the Akida Development Environment ...

Cray delivers powerful supercomputer dedicated to astronomy to National Astronomical Observatory of Japan ...

Intel stops production of Knights Landing/Xeon Phi processors ...

AFRL and IBM unveil world's largest neuromorphic digital synaptic supercomputer ...

Supermicro joins Board of the Storage Networking Industry Association to accelerate all-flash NVMe storage advancements and adoption ...

Underlying mechanism discovered for magnetic effect in superconducting spintronics ...

Applications

Oracle TimesTen Scaleout sets new performance standard for in-memory databases ...

Artificial Intelligence in Cybersecurity wins Lorentz-eScience competition 2018 ...

ACM's SIGHPC to announce 2018 Fellowship winners ...

International IEEE eScience Conference issues Call for conference travel and attendance grants ...

Texas Women in HPC Chapter formed ...

Researchers find new way to target flu virus ...

Newest supercomputer to help develop fusion energy in international device ...

XSEDE allocates $7,3 million worth of computing time to U.S. researchers in latest allocation cycle ...

Ruby Mendenhall charts progress using HPC and Big Data to flag unidentified historical sources on African American women's lives ...

XSEDE announces 2018-2019 Campus Champions Fellows ...

The Cloud

On-demand high performance Cloud computing for today's most demanding workflows offered by PADT in partnership with Nimbix ...

Share your thoughts and vote on the evolution of EOSC and FAIR data ...

EGI Foundation and Terradue signed a Memorandum of Understanding ...

HPE advances intelligent storage capabilities with AI and Cloud automation for HPE 3PAR ...

Demon in the details of quantum thermodynamics


This is Kater Murch in front of a dilution refrigerator. Credit: Joe Angeles/Washington University.
25 Jul 2018 St. Louis - Thermodynamics is one of the most human of scientific enterprises, according to Kater Murch, associate professor of physics in Arts & Sciences at Washington University in St. Louis.

"It has to do with our fascination of fire and our laziness", he stated. "How can we get fire" - or heat - "to do work for us?"

Now, Kater Murch and colleagues have taken that most human enterprise down to the intangible quantum scale - that of ultra low temperatures and microscopic systems - and discovered that, as in the macroscopic world, it is possible to use information to extract work.

There is a catch, though: Some information may be lost in the process.

"We've experimentally confirmed the connection between information in the classical case and the quantum case", Kater Murch stated, "and we're seeing this new effect of information loss."

The results were published in the July 20 issue of Physical Review Letters .

The international team included Eric Lutz of the University of Stuttgart; J. J. Alonzo of the University of Erlangen-Nuremberg; Alessandro Romito of Lancaster University; and Mahdi Naghiloo, a Washington University graduate research assistant in physics.

That we can get energy from information on a macroscopic scale was most famously illustrated in a thought experiment known as Maxwell's Demon. The "demon" presides over a box filled with molecules. The box is divided in half by a wall with a door. If the demon knows the speed and direction of all of the molecules, it can open the door when a fast-moving molecule is moving from the left half of the box to the right side, allowing it to pass. It can do the same for slow particles moving in the opposite direction, opening the door when a slow-moving molecule is approaching from the right, headed left. ­

After a while, all of the quickly-moving molecules are on the right side of the box. Faster motion corresponds to higher temperature. In this way, the demon has created a temperature imbalance, where one side of the box is hotter. That temperature imbalance can be turned into work - to push on a piston as in a steam engine, for instance. At first the thought experiment seemed to show that it was possible create a temperature difference without doing any work, and since temperature differences allow you to extract work, one could build a perpetual motion machine - a violation of the second law of thermodynamics.

"Eventually, scientists realized that there's something about the information that the demon has about the molecules", Kater Murch stated. "It has a physical quality like heat and work and energy."

His team wanted to know if it would be possible to use information to extract work in this way on a quantum scale, too, but not by sorting fast and slow molecules. If a particle is in an excited state, they could extract work by moving it to a ground state. If it was in a ground state, they wouldn't do anything and wouldn't expend any work.

But they wanted to know what would happen if the quantum particles were in an excited state and a ground state at the same time, analogous to being fast and slow at the same time. In quantum physics, this is known as a superposition.

"Can you get work from information about a superposition of energy states?" Kater Murch asked. "That's what we wanted to find out."

There's a problem, though. On a quantum scale, getting information about particles can be a bit ... tricky.

"Every time you measure the system, it changes that system", Kater Murch stated. And if they measured the particle to find out exactly what state it was in, it would revert to one of two states: excited, or ground.

This effect is called quantum backaction. To get around it, when looking at the system, researchers - who were the "demons" - didn't take a long, hard look at their particle. Instead, they took what was called a "weak observation". It still influenced the state of the superposition, but not enough to move it all the way to an excited state or a ground state; it was still in a superposition of energy states. This observation was enough, though, to allow the researchers track with fairly high accuracy, exactly what superposition the particle was in - and this is important, because the way the work is extracted from the particle depends on what superposition state it is in.

To get information, even using the weak observation method, the researchers still had to take a peek at the particle, which meant they needed light. So they sent some photons in, and observed the photons that came back.

"But the demon misses some photons", Kater Murch stated. "It only gets about half. The other half are lost." But - and this is the key - even though the researchers didn't see the other half of the photons, those photons still interacted with the system, which means they still had an effect on it. The researchers had no way of knowing what that effect was.

They took a weak measurement and got some information, but because of quantum backaction, they might end up knowing less than they did before the measurement. On the balance, that's negative information.

And that's weird.

"Do the rules of thermodynamics for a macroscopic, classical world still apply when we talk about quantum superposition?" Kater Murch asked. "We found that yes, they hold, except there's this weird thing. The information can be negative. I think this research highlights how difficult it is to build a quantum computer", Kater Murch stated.

"For a normal computer, it just gets hot and we need to cool it. In the quantum computer you are always at risk of losing information."

Source: Washington University in St. Louis

Back to Table of contents

Primeur weekly 2018-07-30

Focus

Verne Global turns clever SME ideas into Cloud compute reality with hpcDIRECT in free-cooled Icelandic data centres ...

Opin Kerfi goes big with HPC cluster leasing and co-location in Iceland offering free cooling and purity of air ...

Quantum computing

World-first quantum computer simulation of chemical bonds using trapped ions ...

Demon in the details of quantum thermodynamics ...

Tuning into quantum: Scientists unlock signal frequency control of precision atom qubits ...

Hardware

BrainChip to showcase neuromorphic computing solutions at MPSoC ...

BrainChip unveils the Akida Development Environment ...

Cray delivers powerful supercomputer dedicated to astronomy to National Astronomical Observatory of Japan ...

Intel stops production of Knights Landing/Xeon Phi processors ...

AFRL and IBM unveil world's largest neuromorphic digital synaptic supercomputer ...

Supermicro joins Board of the Storage Networking Industry Association to accelerate all-flash NVMe storage advancements and adoption ...

Underlying mechanism discovered for magnetic effect in superconducting spintronics ...

Applications

Oracle TimesTen Scaleout sets new performance standard for in-memory databases ...

Artificial Intelligence in Cybersecurity wins Lorentz-eScience competition 2018 ...

ACM's SIGHPC to announce 2018 Fellowship winners ...

International IEEE eScience Conference issues Call for conference travel and attendance grants ...

Texas Women in HPC Chapter formed ...

Researchers find new way to target flu virus ...

Newest supercomputer to help develop fusion energy in international device ...

XSEDE allocates $7,3 million worth of computing time to U.S. researchers in latest allocation cycle ...

Ruby Mendenhall charts progress using HPC and Big Data to flag unidentified historical sources on African American women's lives ...

XSEDE announces 2018-2019 Campus Champions Fellows ...

The Cloud

On-demand high performance Cloud computing for today's most demanding workflows offered by PADT in partnership with Nimbix ...

Share your thoughts and vote on the evolution of EOSC and FAIR data ...

EGI Foundation and Terradue signed a Memorandum of Understanding ...

HPE advances intelligent storage capabilities with AI and Cloud automation for HPE 3PAR ...