Navigation Links
Physicists discover how fundamental particles lose track of quantum mechanical properties
Date:3/13/2008

(New Orleans, La.) In todays Science Express, the advance online publication of the journal Science, researchers report a series of experiments that mark an important step toward understanding a longstanding fundamental physics problem of quantum mechanics. The scientists presented their findings at the annual meeting of the American Physical Society here this week.

The problem the physicists addressed is how a fundamental particle in matter loses track of its quantum mechanical properties through interactions with its environment.

The research was performed by scientists at the California NanoSystems Institute at the University of California, Santa Barbara and the U. S. Department of Energy Ames Laboratory in Iowa.

At the quantum level things like particles or light waves behave in ways very different from what scientists expect in a human-scale world. In the quantum world, for example, an electron can exist in two places at the same time, what is called a "superposition" of states, or spin up and down at the same time.

Quantum mechanics in computing could lead to communication with no possible eavesdropping, lightning-fast database searches, and code-cracking ability.

The answer to the problem the researchers have tackled is key to unraveling how the classical world in which we live emerges from all the interacting quantum particles in matter. This scientific query surrounds the basic quantum dynamics of a single particle spin coupled to a collection, or bath, of random spins. This scenario describes the underlying behavior of a broad class of materials around us, ranging from quantum spin tunneling in magnetic molecules to nuclear magnetic resonance in semiconductors.

We were stunned by these unexpected experimental results, and extremely excited by the ability to control and monitor single quantum states, especially at room temperature, said author David Awschalom, a professor of physics at UC Santa Barbara. Awschalom is affiliated with the California NanoSystems Institute at UCSB and is the Director of the Center for Spintronics & Quantum Computation, also at the university.

Recently the issue of how fundamental particles lose track of quantum mechanical properties through interaction with the environment has gained crucial importance in the field of quantum information. In this area, robust manipulation of quantum states promises enormous speedups over classical computation. Keeping track of the quantum phase is essential for keeping the quantum information, and insight into loss of the phase will greatly help to mitigate this process.

Experimental work on this subject has thus far been hindered by the lack of high-fidelity coherent control of a single spin in nature and our inability to directly influence the bath dynamics.

In a collaboration between physicists in Awschaloms research group at UCSB and Slava Dobrovitski, a visiting scientist from Ames Laboratory in Iowa, a series of experiments were undertaken that utilized electron spins in diamond to investigate different regimes of spin-bath interactions, and provide much information about the decoherence dynamics.

The scientists use diamond crystals to study a single electron spin tied to an adjustable collection of nearby spins. Two features of diamond that make this system viable for unprecedented investigations into the coherent dynamics are the precise optical control of a single spin that is unique to diamond, and the magnetic tunability of the spin-bath and intrabath dynamics with small permanent magnets. Their teams observations contain a number of extraordinary discoveries, such as the time-dependent disappearance and reappearance of quantum oscillations of the spins in the diamond lattice.

To our surprise, when looking at longer times, the oscillations disappeared then re-appeared, said co-author Ronald Hanson, a postdoctoral student at UCSB during this period who is now a professor at the Kavli Institute of Nanoscience Delft, at Delft University of Technology, in the Netherlands. At first it looked like an artifact, but repeated measurements reproduced this behavior.

The problem of a single spin coupled to a bath of spins has been the subject of an intense international research effort, as this conceptual framework describes the physical behavior of a number of real systems. Among others, these include atomic and electronic spins that are prime candidates for implementing quantum information processors and coherent spintronics devices.

A series of direct experiments coupled to theoretical simulations demonstrate that spins in diamond serve as a nearly ideal, adjustable, model of central spin.

This work demonstrates a rare level of synergy between experiment, analytical theory, and computer simulations, said Dobrovitski. These three constituents all agree, support, and complement each other. Together, they give a lucid qualitative picture of what happens with spin centers in diamond, and, at the same time, provide a quantitatively accurate description. This agreement is hard to anticipate in advance for such complex systems, where many nuclear and electron quantum spins interact with each other.

Studies of the quantum dynamics of spins in diamond is an emerging topic involving several leading research groups worldwide. It may also be important in the context of recent interest in possible carbon-based electronic devices employing carbon nanotubes and/or graphene.


'/>"/>

Contact: Gail Gallessich
gail.g@ia.ucsb.edu
805-893-7220
University of California - Santa Barbara
Source:Eurekalert

Related biology technology :

1. Physicists discover gold can be magnetic on the nanoscale
2. Sheet of carbon atoms acts like a billiard table, physicists find
3. Sheet of carbon atoms acts like a billiard table, physicists find
4. Physicists pin down spin of surface atoms
5. Spermatech Selects Evotec as Partner for High-Throughput Screening and Lead Discovery
6. Monogram Biosciences and Avexa Announce Exclusive Collaboration to Support New HIV Drug Discovery and Development Efforts
7. Surface dislocation nucleation: Strength is but skin deep at the nanoscale, Penn engineers discover
8. BioCrossroads Launches www.biocrossroadslinx.com and Releases Report on Biopharma Discovery and Development Contract Services
9. European Company NovaSecta Joins First Chinese CRO Service Alliance for Drug Discovery Solutions
10. Contract Services for Big Pharma and Biotechs Driving Growth and Innovation from Discovery to Clinical Trials
11. Xenon Announces Appointment of VP, Discovery Research
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:12/2/2016)... ... December 01, 2016 , ... Aerocom Healthcare ( http://www.aerocomhealthcare.com ), ... present its chain-of-custody solution for tracking and securing medications at booth 676 at ... 2016. , Aerocom has a proven solution for tracking medications via its system ...
(Date:12/2/2016)... ... December 02, 2016 , ... ... and biotechnology companies dedicated to collaboratively developing improved chemistry, manufacturing and control ... vendor-supported, portable online UHPLC, with robust, probe-based sampling. , Online liquid ...
(Date:11/30/2016)... ... November 30, 2016 , ... BEI Kimco, a brand of ... flexure design that ensures high alignment accuracy by preventing unwanted shaft rotation. The ... where extreme precision is required, such as in medical equipment, laboratory instrumentation, clean ...
(Date:11/30/2016)... Nov. 30, 2016  The Allen Institute for ... the first publicly available collection of gene edited, ... target key cellular structures with unprecedented clarity. Distributed ... powerful tools are a crucial first step toward ... understand what makes human cells healthy and what ...
Breaking Biology Technology:
(Date:6/16/2016)... , June 16, 2016 ... size is expected to reach USD 1.83 billion ... Grand View Research, Inc. Technological proliferation and increasing ... applications are expected to drive the market growth. ... , The development of advanced multimodal ...
(Date:6/7/2016)... -- Syngrafii Inc. and San Antonio Credit Union (SACU) ... Syngrafii,s patented LongPen™ eSignature "Wet" solution into SACU,s ... in greater convenience for SACU members and operational ... document workflow and compliance requirements. Logo ... Highlights: ...
(Date:6/2/2016)... , June 2, 2016 Perimeter ... Platforms, Unmanned Systems, Physical Infrastructure, Support & Other Service  ... visiongain offers comprehensive analysis of the global ... market will generate revenues of $17.98 billion in 2016. ... DVTEL Inc, a leader in software and hardware technologies ...
Breaking Biology News(10 mins):