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Primeur weekly 2014-08-04

Special

Adaptive's Wolfgang Dreyer talks about Moab 8.0 and Nitro products, and mutual collaboration with partners ...

New PRACE Council Chair Sanzio Bassini to unfold future plans for Europe's advanced research infrastructure ...

Exascale supercomputing

UK business set to revolutionise supercomputing with prototype optical processor ...

The Cloud

PSSC Labs CloudOOP 12000 certified compatible with Cloudera Enterprise 5 ...

New eResearch Cloud is NeCTAR of the gods to Tassie scientists ...

New tools help neuroscientists analyze 'Big Data' ...

Oracle customers plug into the Cloud with Oracle Database 12c ...

Breakthrough elastic Cloud-to Cloud networking unveiled by AT&T, IBM Research and ACS ...

Oracle Solaris 11.2 now generally available ...

Oracle buys TOA Technologies ...

National Instruments transforms global HR with Oracle HCM Cloud ...

Desktop Grids

IBM to make free supercomputing power available to sustainability scientists ...

EuroFlash

Bright Computing raises $14.5 million Series B to accelerate its HPC, Hadoop and OpenStack business ...

PRACE 9th Call for Proposals connects the international HPC ecosystem ...

Computational biologists from Saarbrücken simplify diagnosis for hereditary diseases ...

Bull to issue 2014 half-year results ...

Bull launches IT bulletin, an on-line news review dedicated to IT expertise ...

IBM acquires CrossIdeas to expand security offerings with identity intelligence ...

Spin-based electronics: New material successfully tested ...

USFlash

Cray reports second quarter 2014 financial results ...

Spin diagnostics: MRI for a quantum simulation ...

Big Data confirms climate extremes are here to stay ...

Steering quantum evolution and using probes to conduct continuous error correction in quantum computers ...

AMD announces the availability of 64-bit ARM Opteron developer kits ...

Red Hat launches ARM Partner Early Access Programme for partner ecosystem ...

CoolIT Systems announces strategic OEM and distribution agreement with CES Group ...

Steering quantum evolution and using probes to conduct continuous error correction in quantum computers


Irfan Siddiqi, UC Berkeley
30 Jul 2014 Berkeley - One of the famous examples of the weirdness of quantum mechanics is the paradox of Schrödinger's cat. If you put a cat inside an opaque box and make his life dependent on a random event, when does the cat die? When the random event occurs, or when you open the box?

Though common sense suggests the former, quantum mechanics - or at least the most common "Copenhagen" interpretation enunciated by Danish physicist Neils Bohr in the 1920s - says it's the latter. Someone has to observe the result before it becomes final. Until then, paradoxically, the cat is both dead and alive at the same time.

University of California, Berkeley, physicists have for the first time showed that, in fact, it's possible to follow the metaphorical cat through the whole process, whether he lives or dies in the end.

"Gently recording the cat's paw prints both makes it die, or come to life, as the case may be, and allows us to reconstruct its life history", stated Irfan Siddiqi, UC Berkeley associate professor of physics, who is senior author of a cover article describing the result in the July 31 issue of the journalNature.

The Schrödinger's cat paradox is a critical issue in quantum computers, where the input is an entanglement of states - like the cat's entangled life and death - yet the answer to whether the animal is dead or alive has to be definite.

"To Bohr and others, the process was instantaneous - when you opened the box, the entangled system collapsed into a definite, classical state. This postulate stirred debate in quantum mechanics", Irfan Siddiqi stated. "But real-time tracking of a quantum system shows that it's a continuous process, and that we can constantly extract information from the system as it goes from quantum to classical. This level of detail was never considered accessible by the original founders of quantum theory."

For quantum computers, this would allow continuous error correction. The real world, everything from light and heat to vibration, can knock a quantum system out of its quantum state into a real-world, so-called classical state, like opening the box to look at the cat and forcing it to be either dead or alive. A big question regarding quantum computers, Irfan Siddiqi said, is whether you can extract information without destroying the quantum system entirely.

"This gets around that fundamental problem in a very natural way", he stated. "We can continuously probe a system very gently to get a little bit of information and continuously correct it, nudging it back into line, toward the ultimate goal."

In the world of quantum physics, a system can be in two superposed states at the same time, as long as no one is observing. An observation perturbs the system and forces it into one or the other. Physicists say that the original entangled wave functions collapsed into a classical state.

In the past 10 years, theorists such as Andrew N. Jordan, professor of physics at the University of Rochester and co-author of theNaturepaper, have developed theories predicting the most likely way in which a quantum system will collapse.

"The Rochester team developed new mathematics to predict the most likely path with high accuracy, in the same way one would use Newtown's equations to predict the least cumbersome path of a ball rolling down a mountain", Irfan Siddiqi stated. "The implications are significant, as now we can design control sequences to steer a system along a certain trajectory. For example, in chemistry one could use this to prefer certain products of a reaction over others."

Lead researcher Steve Weber, a graduate student in Irfan Siddiqi's group, and Irfan Siddiqi's former postdoctoral fellow Kater Murch, now an assistant professor of physics at Washington University in St. Louis, proved Andrew N. Jordan correct. They measured the trajectory of the wave function of a quantum circuit - a qubit, analogous to the bit in a normal computer - as it changed. The circuit, a superconducting pendulum, could be in two different energy states and was coupled to a second circuit to read out the final voltage, corresponding to the pendulum's frequency.

"If you did this experiment many, many times, measuring the road the system took each time and the states it went through, we could determine what the most likely path is", Irfan Siddiqi stated. "Then we could design a control sequence to take the road we want to take for a given quantum evolution."

If you probed a chemical reaction in detail, for example, you could find the most likely path the reaction would take and design a way to steer the reaction to the products you want, not the most likely, Irfan Siddiqi said.

"The experiment demonstrates that, for any choice of final quantum state, the most likely or 'optimal path' connecting them in a given time can be found and predicted", Andrew N. Jordan stated. "This verifies the theory and opens the way for active quantum control techniques."

The work was supported in part by the Office of Naval Research and the Office of the Director of National Intelligence (ODNI) of the Intelligence Advanced Research Projects Activity (IARPA), through the Army Research Office.

Source: University of California - Berkeley

Back to Table of contents

Primeur weekly 2014-08-04

Special

Adaptive's Wolfgang Dreyer talks about Moab 8.0 and Nitro products, and mutual collaboration with partners ...

New PRACE Council Chair Sanzio Bassini to unfold future plans for Europe's advanced research infrastructure ...

Exascale supercomputing

UK business set to revolutionise supercomputing with prototype optical processor ...

The Cloud

PSSC Labs CloudOOP 12000 certified compatible with Cloudera Enterprise 5 ...

New eResearch Cloud is NeCTAR of the gods to Tassie scientists ...

New tools help neuroscientists analyze 'Big Data' ...

Oracle customers plug into the Cloud with Oracle Database 12c ...

Breakthrough elastic Cloud-to Cloud networking unveiled by AT&T, IBM Research and ACS ...

Oracle Solaris 11.2 now generally available ...

Oracle buys TOA Technologies ...

National Instruments transforms global HR with Oracle HCM Cloud ...

Desktop Grids

IBM to make free supercomputing power available to sustainability scientists ...

EuroFlash

Bright Computing raises $14.5 million Series B to accelerate its HPC, Hadoop and OpenStack business ...

PRACE 9th Call for Proposals connects the international HPC ecosystem ...

Computational biologists from Saarbrücken simplify diagnosis for hereditary diseases ...

Bull to issue 2014 half-year results ...

Bull launches IT bulletin, an on-line news review dedicated to IT expertise ...

IBM acquires CrossIdeas to expand security offerings with identity intelligence ...

Spin-based electronics: New material successfully tested ...

USFlash

Cray reports second quarter 2014 financial results ...

Spin diagnostics: MRI for a quantum simulation ...

Big Data confirms climate extremes are here to stay ...

Steering quantum evolution and using probes to conduct continuous error correction in quantum computers ...

AMD announces the availability of 64-bit ARM Opteron developer kits ...

Red Hat launches ARM Partner Early Access Programme for partner ecosystem ...

CoolIT Systems announces strategic OEM and distribution agreement with CES Group ...