Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Molecular Engineers Record an Electron’s Quantum Behavior

18.08.2014

A team of researchers led by the University of Chicago has developed a technique to record the quantum mechanical behavior of an individual electron contained within a nanoscale defect in diamond.

Their technique uses ultrafast pulses of laser light both to control the defect’s entire quantum state and observe how that single electron state changes over time. The work appears in this week’s online Science Express and will be published in print later this month in Science.


Courtesy of Awschalom Lab/University of Chicago

These images show the diamond sample with a hemispherical lens (right and lower left), and the location of a single electron spin/quantum state visible through its light emission (upper left). The scale bar on the image at upper left measures five microns, the approximate diameter of a red blood cell.

This research contributes to the emerging science of quantum information processing, which demands that science leave behind the unambiguous universe of traditional binary logic—0 or 1—and embrace the counterintuitive quantum world, where behavior is radically different from what humans experience every day. While people are generally content being in one place at a time, electrons can be in many states at once.

The team researches a quantum mechanical property of the electron known as spin. Much like conventional computers use the charge state of electrons to constitute bits of information, a quantum computer would use the spin state of a single electron as its quantum bit, or qubit.

The work could accelerate development of quantum computing devices, and the extra computing power that would come with them, because it will be easier to identify materials that have appropriate quantum properties.

The spin system studied is known as the nitrogen-vacancy (NV) center, an atom-sized defect that occurs naturally in diamond, consisting of a nitrogen atom next to a vacant spot in the crystal lattice. “These defects have garnered great interest over the past decade, providing a test-bed system for developing semiconductor quantum bits as well as nanoscale sensors,” said team leader David Awschalom, the Liew Family Professor of Molecular Engineering at UChicago. “Here, we were able to harness light to completely control the quantum state of this defect at extremely high speeds.”

Quantum snapshots

In this new technique, the researchers locate a single NV center and then illuminate it with a pair of extremely short pulses of laser light. Each pulse lasts less than a picosecond (or a millionth of a millionth of a second). The first pulse excites the quantum states of the defect-bound electron, which then change or evolve in characteristic ways. The second pulse stops that evolution, capturing a picture of the quantum state at that elapsed time.

By progressively extending the elapsed time between the two pulses, the team creates a sequence of quantum-state snapshots—a movie of how the quantum state changes in time. The elapsed time can be as short as femtoseconds (a billionth of a millionth of a second) or as long as nanoseconds (a thousandth of a millionth of a second). On the human scale, this range of time is like the difference between an hour and a century.

Having this vast range of timescales makes the technique especially valuable. The electron is susceptible and interacts with its complex local environment in many different ways, each with a characteristic timescale. Being able to test a wide range of these timescales gives a far more complete picture of the dynamics of the NV center than has been obtained previously.

“Our goal was to push the limits of quantum control in these remarkable defect systems,” explained Lee Bassett, co-lead author on the paper and now an assistant professor of electrical and systems engineering at the University of Pennsylvania, “but the technique also provides an exciting new measurement tool. By using pulses of light to direct the defect’s quantum dynamics on super-short timescales, we can extract a wealth of information about the defect and its environment.”

“It’s quite a versatile technique, providing a full picture of the excited state of the quantum defect,” said F. Joseph Heremans, a postdoctoral scholar at UChicago, the other co-lead author on the paper. “Previous work on the nitrogen-vacancy center has hinted at some of these processes, but here, simply through the application of these ultrafast pulses, we get a much richer understanding of this quantum beast.”

Spin control

It’s not just a matter of observation, though. “This technique also provides a means of control of the spin state—an important precursor for any quantum information system,” said Evelyn Hu, a professor of applied physics and electrical engineering at Harvard University, who is not connected with the new work.

In addition, the method is not limited to investigating this particular defect. It could be applied to quantum states of matter in a host of materials and technologies, including many semiconductor materials. “You only have to be able to use light to transfer an electron between a ground state and an excited state,” said Awschalom.

Professor Guido Burkard, theoretical physicist at the University of Konstanz and a co-author on the paper, remarked, “This technique offers a path toward understanding and controlling new materials at the atomic level.”

Hu agrees that the technique opens many new avenues. “Each new system will pose new challenges to understanding the energy levels, local environments, and other properties, but the general approach should provide an enormous step forward for the field,” said Hu.

In addition to researchers from UChicago’s Institute for Molecular Engineering, the team included collaborators at the University of California, Santa Barbara (co-lead author Lee Bassett is now at the University of Pennsylvania), and the University of Konstanz, Germany.— Jane Marie Andrew

Citation: “Ultrafast Optical Control of Orbital and Spin Dynamics in a Solid-State Defect,” by Lee C. Bassett, F. Joseph Heremans, David J. Christle, Christopher G. Yale, Guido Burkard, Bob B. Buckley and David D. Awschalom, Science Express, Aug. 14, 2014.

Funding: Air Force Office of Scientific Research and the National Science Foundation.

Contact Information

Steve Koppes
Associate News Director
skoppes@uchicago.edu
Phone: 773-702-8366

Steve Koppes | newswise
Further information:
http://www.uchicago.edu

Further reports about: Molecular defect electrons materials nitrogen-vacancy semiconductor technique

More articles from Physics and Astronomy:

nachricht Enhancing the quantum sensing capabilities of diamond
23.11.2017 | The Hebrew University of Jerusalem

nachricht Quantum optics allows us to abandon expensive lasers in spectroscopy
22.11.2017 | Lomonosov Moscow State University

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: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Underwater acoustic localization of marine mammals and vehicles

23.11.2017 | Information Technology

Enhancing the quantum sensing capabilities of diamond

23.11.2017 | Physics and Astronomy

Meadows beat out shrubs when it comes to storing carbon

23.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>