Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Physicists team up to learn how quantum mechanical states break down

25.03.2008
Collaborative Effort Moves Quantum Computers One Step Closer to Reality

Researchers at the U. S. Department of Energy’s Ames Laboratory, the University of California, Santa Barbara, and Microsoft Station Q have made significant advancements in understanding a fundamental problem of quantum mechanics – one that is blocking efforts to develop practical quantum computers with processing speeds far superior to conventional computers.

Their respective theoretical and experimental studies investigate how microscopic objects lose their quantum-mechanical properties through interactions with the environment. The results of the researchers’ investigations were announced at the American Physical Society meeting held March 10-14 in New Orleans and also reported in Science Express, the advance online publication of the journal Science.

“Quantum-mechanical particles can interact with their environments: visible light, or photons; molecules of the air; crystal vibrations; and many other things,” said Viatcheslav Dobrovitski, an Ames Laboratory theoretical physicist. “All these uncontrollable interactions randomly ‘kick’ the system, destroying quantum phases, or the ability of particles to preserve coherence between different quantum states.”

Quantum coherence is essential to developing quantum computers in which information would be stored and processed on quantum mechanical states of quantum bits, called qubits. So the self-destructive nature of quantum-mechanical states interacting with the environment is a huge problem.

To find out more about how quantum coherence breaks down and to study the dynamics of this decoherence process, the Ames Lab, UCSB and Microsoft Station Q team studied certain spin systems, called nitrogen-vacancy, N-V, impurity centers, in diamond. (Spin is the intrinsic angular momentum of an elementary particle, such as an electron.) N-V impurity centers in diamond are interesting because of the ability to control and manipulate the quantum state of a single center, allowing scientists to study the loss of coherence at a single-particle scale.

The Ames Lab, UCSB and Microsoft Station Q researchers were able to manipulate the N-V centers interacting with an environment of nitrogen spins in a piece of diamond. Amazingly, the physicists were able to tune and adjust the environmental interference extremely well, accessing surprisingly different regimes of decoherence in a single system. The scientists showed that the degree of interaction between the qubit and the interfering environment could be regulated by applying a moderate magnetic field. By using analytical theory and advanced computer simulations, they gained a clear qualitative picture of the decoherence process in different regimes, and also provided an excellent quantitative description of the quantum spin dynamics. The experiments were performed at room temperature rather than the extremely low temperatures often required for most atomic scale investigations.

These images depicting coherently driven spin oscillations of a nitrogen-vacancy (N-V) center show the excellent level of agreement achieved between experiment, analytical theory and computer simulation in the research on the fundamental physics of a single quantum spin by Ames Laboratory, the University of California, Santa Barbara, and Microsoft Station Q.

Dobrovitski noted that quantum coherence of N-V centers in diamond is being studied by leading scientific groups worldwide. “The combined efforts of these groups could help in opening the way to developing a series of interacting qubits – steps to a quantum computer – where each N-V center would act as a qubit,” he said.

“In addition to quantum computers, quantum coherence plays an important role for future less exotic, but not less spectacular, applications,” said Dobrovitski. “For instance, quantum spins can be employed to develop coherent spintronic devices, which would work much faster than traditional microelectronic elements and dissipate much less energy. Quantum coherence between many spins can be employed to perform measurements with ultrahigh precision for metrology applications or to drastically increase the sensitivity of modern nuclear magnetic resonance, NMR, or electron spin resonance, ESR, experiments.

“However, in order to implement these appealing proposals, a very good understanding of quantum coherence and its destruction by the environment is needed,” Dobrovitski emphasized. In particular, from the application point of view, it is important to understand the loss of coherence of quantum systems in solid-state environments, which form the basis of modern technology.”

The DOE Office of Science, Basic Energy Sciences Office and the Air Force Office of Scientific Research funded this research on the fundamental physics of a single quantum spin.

Ames Laboratory is operated for the Department of Energy by Iowa State University. The Lab conducts research into various areas of national concern, including the synthesis and study of new materials, energy resources, high-speed computer design, and environmental cleanup and restoration.

Saren Johnston | EurekAlert!
Further information:
http://www.ameslab.gov

More articles from Physics and Astronomy:

nachricht New NASA study improves search for habitable worlds
20.10.2017 | NASA/Goddard Space Flight Center

nachricht Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>