Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Physicists Isolate Bound States in Graphene Superconductor Junctions

Scanning electron micrograph of a device with an overlaid measurement circuit. Graphene is false coloured orange, large end contacts are Cr/Au and middle tunnel probes are Pb/In. The scale bar is 5 ým. Credit Nature
Scanning electron micrograph of a device with an overlaid measurement circuit. Graphene is false coloured orange, large end contacts are Cr/Au and middle tunnel probes are Pb/In. The scale bar is 5 ým. Credit Nature

Abstract:
Illinois researchers have documented the first observations of some unusual physics when two prominent electric materials are connected: superconductors and graphene.

Physicists Isolate Bound States in Graphene Superconductor Junctions

Champaign, IL | Posted on February 15th, 2011

Led by University of Illinois physics professor Nadya Mason, the group published its findings in the journal Nature Physics.

When a current is applied to a normal conductor, such as metal or graphene, it flows through the material as a stream of single electrons. By contrast, electrons travel in pairs in superconductors. Yet when a normal material is sandwiched between superconductors, the normal metal can carry the supercurrent.

Normal metals can adopt superconducting capacity because the paired electrons from the superconductor are translated to special electron-hole pairs in the normal metal, called Andreev bound states (ABS).

"If you have two superconductors with a normal metal between, you can actually transport the superconductivity across the normal material via these bound states, even though the normal material doesn't have the electron pairing that the superconductors do," Mason said.

ABS are extremely difficult to measure or to observe directly. Researchers can measure conduction and overall magnitude of a current, but have not been able to study individual ABS to understand the fundamental physics contributing to these unique states.

Mason's group developed a method of isolating individual ABS by connecting superconducting probes to tiny, nanoscale flakes of graphene called quantum dots. This confined the ABS to discrete energy levels within the quantum dot, allowing the researchers to measure the superconducting ABS individually and even to manipulate them.

"Before this, it wasn't really possible to understand the fundamentals of what is transporting the current," Mason said. "Watching an individual bound state allows you to change one parameter and see how one mode changes. You can really get at a systematic understanding. It also allows you to manipulate ABS to use them for different things that just couldn't be done before."

Superconductor junctions have been proposed for use as superconducting transistors or bits for quantum computers, called qubits. Greater understanding of ABS may enable other applications as well. In addition, it may be possible to use the superconducting graphene quantum dots themselves as solid-state qubits.

"This is a unique case where we found something that we couldn't have discovered without using all of these different elements - without the graphene, or the superconductor, or the quantum dot, it wouldn't have worked. All of these are really necessary to see this unusual state," Mason said.

The U.S. Department of Energy supported this work, conducted at the Frederick Seitz Materials Research Laboratory at Illinois.

The paper, "Transport Through Andreev Bound States in a Graphene Quantum Dot," is online at www.nature.com/nphys/journal/vaop/ncurrent/full/nphys1911.html.

####

For more information, please click here

Contacts:
Liz Ahlberg
Physical Sciences Editor
217-244-1073

Copyright © University of Illinois at Urbana-Champaign

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Nanoparticle exposure can awaken dormant viruses in the lungs January 17th, 2017

Nanoscale view of energy storage January 16th, 2017

Seeing the quantum future... literally: What if big data could help you see the future and prevent your mobile phone from breaking before it happened? January 16th, 2017

NUS researchers achieve major breakthrough in flexible electronics: New classes of printable electrically conducting polymer materials make better electrodes for plastic electronics and advanced semiconductor devices January 14th, 2017

Chemistry on the edge: Experiments at Berkeley Lab confirm that structural defects at the periphery are key in catalyst function January 13th, 2017

Physics

Seeing the quantum future... literally: What if big data could help you see the future and prevent your mobile phone from breaking before it happened? January 16th, 2017

Govt.-Legislation/Regulation/Funding/Policy

Nanoscale view of energy storage January 16th, 2017

Chemistry on the edge: Experiments at Berkeley Lab confirm that structural defects at the periphery are key in catalyst function January 13th, 2017

Deciphering the beetle exoskeleton with nanomechanics: Understanding exoskeletons could lead to new, improved artificial materials January 12th, 2017

New laser based on unusual physics phenomenon could improve telecommunications, computing January 12th, 2017

Possible Futures

Nanoscale view of energy storage January 16th, 2017

Seeing the quantum future... literally: What if big data could help you see the future and prevent your mobile phone from breaking before it happened? January 16th, 2017

NUS researchers achieve major breakthrough in flexible electronics: New classes of printable electrically conducting polymer materials make better electrodes for plastic electronics and advanced semiconductor devices January 14th, 2017

Nanoscale Modifications can be used to Engineer Electrical Contacts for Nanodevices January 13th, 2017

Academic/Education

Oxford Nanoimaging report on how the Nanoimager, a desktop microscope delivering single molecule, super-resolution performance, is being applied at the MRC Centre for Molecular Bacteriology & Infection November 22nd, 2016

The University of Applied Sciences in Upper Austria uses Deben tensile stages as an integral part of their computed tomography research and testing facility October 18th, 2016

Enterprise In Space Partners with Sketchfab and 3D Hubs for NewSpace Education October 13th, 2016

New Agricultural Research Center Debuts at UCF October 12th, 2016

Nanotubes/Buckyballs/Fullerenes

Captured on video: DNA nanotubes build a bridge between 2 molecular posts: Research may lead to new lines of direct communication with cells January 9th, 2017

Nano-chimneys can cool circuits: Rice University scientists calculate tweaks to graphene would form phonon-friendly cones January 4th, 2017

WPI researchers build liquid biopsy chip that detects metastatic cancer cells in blood December 15th, 2016

Infrared instrumentation leader secures exclusive use of Vantablack coating December 5th, 2016

Quantum Computing

Seeing the quantum future... literally: What if big data could help you see the future and prevent your mobile phone from breaking before it happened? January 16th, 2017

NIST physicists 'squeeze' light to cool microscopic drum below quantum limit January 12th, 2017

First experimental proof of a 70 year old physics theory: First observation of magnetic phase transition in 2-D materials, as predicted by the Nobel winner Onsager in 1943 January 6th, 2017

Diamonds are technologists' best friends: Researchers from the Lomonosov Moscow State University have grown needle- and thread-like diamonds and studied their useful properties December 30th, 2016

Discoveries

Nanoparticle exposure can awaken dormant viruses in the lungs January 17th, 2017

Nanoscale view of energy storage January 16th, 2017

Seeing the quantum future... literally: What if big data could help you see the future and prevent your mobile phone from breaking before it happened? January 16th, 2017

NUS researchers achieve major breakthrough in flexible electronics: New classes of printable electrically conducting polymer materials make better electrodes for plastic electronics and advanced semiconductor devices January 14th, 2017

Announcements

Nanoparticle exposure can awaken dormant viruses in the lungs January 17th, 2017

Nanoscale view of energy storage January 16th, 2017

Seeing the quantum future... literally: What if big data could help you see the future and prevent your mobile phone from breaking before it happened? January 16th, 2017

NUS researchers achieve major breakthrough in flexible electronics: New classes of printable electrically conducting polymer materials make better electrodes for plastic electronics and advanced semiconductor devices January 14th, 2017

Quantum Dots/Rods

Carbon dots dash toward 'green' recycling role: Rice scientists, colleagues use doped graphene quantum dots to reduce carbon dioxide to fuel December 18th, 2016

Two electrons go on a quantum walk and end up in a qudit: Russian scientists find a way to reliably connect quantum elements December 13th, 2016

Trickling electrons: Close to absolute zero, the particles exhibit their quantum nature November 10th, 2016

Notre Dame researchers find transition point in semiconductor nanomaterials September 6th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project