Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nuclear spins get in line

14.11.2011
Electrically controlling the magnetic polarization of nuclei offers a new way to store quantum information

Storing information in long-lasting quantum states is a prerequisite for building quantum computers. Intrinsic properties of nuclei known as magnetic spins are good storage candidates because they interact weakly with their environment; however, controlling them is difficult.

Now, researchers in Japan have demonstrated an all-electrical method for preparing the magnetic states of nuclei that would be useful in storing quantum information. Keiji Ono at the RIKEN Advanced Science Institute, Wako, led the work.

In an atomic nucleus, protons and neutrons pair up such that their magnetic spins align in opposite directions. However, in nuclei with an odd number of protons and neutrons, this pairing is incomplete; thus, they have a so-called ‘magnetic moment’ that points in no particular direction, hindering control.

Nuclear spins are difficult to align except at low temperatures and with large magnetic fields. But in devices called quantum dots, Ono and other researchers have shown they can manipulate the nuclear spins electrically. A quantum dot is made from a semiconductor material of just a few tens of nanometers in size. Using an external voltage, the researchers could add electrons to a quantum dot one at time.

Similar to protons and neutrons, a single electron on a quantum dot possesses a spin that acts like an effective magnetic field on the surrounding nuclear spins. Physicists have used this interaction to control nuclear magnetic moments; but, they had only succeeded in significantly polarizing the nuclear moments in one direction. Ono’s team, however, showed that it is possible to polarize the nuclear moments either up or down—a quantum version of the ‘1’ and ‘0’ on a digital bit.

Ono and his team demonstrated this behavior in a double quantum dot—two quantum dots in series—made from the semiconductor gallium-arsenide. They showed they can ‘pump’ the nuclear spins into a particular direction by using voltages to place one electron on each dot and then polarize their spins such that they are either both up, or both down. As the spins on the dot relaxed, they ‘dragged’ the nuclear spins, polarizing them in the process. The nuclei remained polarized for several milliseconds—significantly longer than the polarized states of electron spins in similar devices.

The work offers a new way of controlling nuclear spins, says Ono, who now plans to study the polarization reversal process of the nuclear spins in more detail. Nuclear spins could “become a ubiquitous resource for storing information in a semiconductor,” he adds.

The corresponding author for this highlight is based at the Low Temperature Physics Laboratory, RIKEN Advanced Science Institute

Reference:

Takahashi, R., Kono, K., Tarucha, S. & Ono, K. Voltage-selective bidirectional polarization and coherent rotation of nuclear spins in quantum dots. Physical Review Letters 107, 026602 (2011).

gro-pr | Research asia research news
Further information:
http://www.riken.jp
http://prl.aps.org/abstract/PRL/v107/i2/e026602
http://www.researchsea.com

More articles from Physics and Astronomy:

nachricht ALMA discovers aluminum around young star
17.05.2019 | National Institutes of Natural Sciences

nachricht JQI researchers shed new light on atomic 'wave function'
17.05.2019 | National Institute of Standards and Technology (NIST)

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: Self-repairing batteries

UTokyo engineers develop a way to create high-capacity long-life batteries

Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...

Im Focus: Quantum Cloud Computing with Self-Check

With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.

Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...

Im Focus: Accelerating quantum technologies with materials processing at the atomic scale

'Quantum technologies' utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.

However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been...

Im Focus: A step towards probabilistic computing

Working group led by physicist Professor Ulrich Nowak at the University of Konstanz, in collaboration with a team of physicists from Johannes Gutenberg University Mainz, demonstrates how skyrmions can be used for the computer concepts of the future

When it comes to performing a calculation destined to arrive at an exact result, humans are hopelessly inferior to the computer. In other areas, humans are...

Im Focus: Recording embryonic development

Scientists develop a molecular recording tool that enables in vivo lineage tracing of embryonic cells

The beginning of new life starts with a fascinating process: A single cell gives rise to progenitor cells that eventually differentiate into the three germ...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

Discovering unusual structures from exception using big data and machine learning techniques

17.05.2019 | Materials Sciences

ALMA discovers aluminum around young star

17.05.2019 | Physics and Astronomy

A new iron-based superconductor stabilized by inter-block charger transfer

17.05.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>