Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Fast quantum computer building block created

Abstract:
The fastest quantum computer bit that exploits the main advantage of the qubit over the conventional bit has been demonstrated by researchers at University of Michigan, U.S. Naval Research Laboratory and the University of California at San Diego.

Fast quantum computer building block created

ANN ARBOR, MI | Posted on August 21st, 2008

The scientists used lasers to create an initialized quantum state of this solid-state qubit at rates of about a gigahertz, or a billion times per second. They can also use lasers to achieve fundamental steps toward programming it.

A conventional bit can be a 0 or a 1. A quantum bit, or qubit, can be both at the same time. Until now, scientists couldn't stabilize that duality.

Physics professor Duncan Steel, doctoral student Xiaodong Xu and their colleagues used lasers to coherently, or stably, trap the spin of one electron confined in a single semiconductor quantum dot. A quantum dot is like a transistor in a conventional computer.

The scientists trapped the spin in a dark state in which they can arbitrarily adjust the amount of 0 and 1 the qubit represents. They call this state "dark" because it does not absorb light. Therefore, light does not cause loss of coherence between the two states. In other words, the light does not destabilize the qubit. A paper on these findings will be published in Nature Physics and is available early in the online edition.

"We are the first to show that you can do this to a single electron in a self-assembled quantum dot," Steel said. "If you're going to do quantum computing, you have to be able to work with one electron at a time."

Spin is an intrinsic property of the electron that isn't a real rotation. Steel compares it to the magnetic poles. Electrons are said to have spin up or down. In quantum computing, the up and down directions represent the 0s and 1s of conventional computing.

Steel's approach to developing a quantum computer is to use ultrafast lasers to manipulate arrays of semiconductor quantum dots, each containing one electron. Quantum logic gates are formed by quantum mechanical interactions between the dots.

Previously in Steel's lab, researchers have used a laser to produce an electron in a state representative of a 1 or a 0 and a small amount of the other state. Now, using two laser frequencies, they have trapped it as a 0 and a 1 at the same time, and they can adjust the amount of each.

Because the electron is trapped in a dark state, applied light can't destroy the coherence. Energy from light can flip the spin of electrons, or quantum bits, which would jumble any information being stored in the bit.

"This dark state is a place where information can be stored without any error," Steel said.

Because of their ability to represent multiple states simultaneously, quantum computers could theoretically factor numbers dramatically faster and with smaller computers than conventional computers. For this reason, they could vastly improve computer security.

"The National Security Agency has said that based on our present technology, we have about a 20-year window of security," Steel said. "That means if we sent up a satellite today, it would take somebody about 20 years to crack the code. Quantum computers will let you develop a code that would be impossible to crack with a conventional computer."

Physicists achieved this by using two continuous wave lasers.

Steel is the Robert J. Hiller Professor of Engineering in the Department of Electrical Engineering and Computer Science as well as a professor in the Physics Department. Xu, a doctoral student in Physics, is first author of the Nature Physics paper. Steel is also an author. The principal investigators include Dan Gammon of the Naval Research Laboratory and physics professor Lu Jeu Sham at the University of California at San Diego.

The paper is called "Coherent Population Trapping of an Electron Spin in a Single Negatively Charged Quantum Dot." It is available online at www.nature.com/nphys/journal/vaop/ncurrent/full/nphys1054.html.

For more information:
Duncan Steel: www.ns.umich.edu/htdocs/public/experts/ExpDisplay.php?ExpID=1226

####

About University of Michigan
The University of Michigan College of Engineering is ranked among the top engineering schools in the country. At more than $130 million annually, its engineering research budget is one of the largest of any public university. Michigan Engineering is home to 11 academic departments and a National Science Foundation Engineering Research Center. The college plays a leading role in the Michigan Memorial Phoenix Energy Institute and hosts the world class Lurie Nanofabrication Facility. Find out more at www.engin.umich.edu.

For more information, please click here

Contacts:
Nicole Casal Moore

734-647-1838

Copyright © University of Michigan

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

New method in the fight against forever chemicals September 13th, 2024

Energy transmission in quantum field theory requires information September 13th, 2024

Breakthrough in proton barrier films using pore-free graphene oxide: Kumamoto University researchers achieve new milestone in advanced coating technologies September 13th, 2024

Quantum researchers cause controlled ‘wobble’ in the nucleus of a single atom September 13th, 2024

Quantum Computing

Quantum researchers cause controlled ‘wobble’ in the nucleus of a single atom September 13th, 2024

Researchers observe “locked” electron pairs in a superconductor cuprate August 16th, 2024

Physicists unlock the secret of elusive quantum negative entanglement entropy using simple classical hardware August 16th, 2024

A 2D device for quantum cooling:EPFL engineers have created a device that can efficiently convert heat into electrical voltage at temperatures lower than that of outer space. The innovation could help overcome a significant obstacle to the advancement of quantum computing technol July 5th, 2024

Discoveries

Energy transmission in quantum field theory requires information September 13th, 2024

Breakthrough in proton barrier films using pore-free graphene oxide: Kumamoto University researchers achieve new milestone in advanced coating technologies September 13th, 2024

Quantum researchers cause controlled ‘wobble’ in the nucleus of a single atom September 13th, 2024

New nanomaterial could transform how we visualise fingerprints: Innovative nanomaterials have the potential to revolutionise forensic science, particularly in the detection of latent (non-visible) fingermarks September 13th, 2024

Announcements

Giving batteries a longer life with the Advanced Photon Source: New research uncovers a hydrogen-centered mechanism that triggers degradation in the lithium-ion batteries that power electric vehicles September 13th, 2024

NYU Abu Dhabi researchers develop novel covalent organic frameworks for precise cancer treatment delivery: NYU Abu Dhabi researchers develop novel covalent organic frameworks for precise cancer treatment delivery September 13th, 2024

New discovery aims to improve the design of microelectronic devices September 13th, 2024

New method in the fight against forever chemicals September 13th, 2024

Quantum Dots/Rods

A new kind of magnetism November 17th, 2023

IOP Publishing celebrates World Quantum Day with the announcement of a special quantum collection and the winners of two prestigious quantum awards April 14th, 2023

Qubits on strong stimulants: Researchers find ways to improve the storage time of quantum information in a spin rich material January 27th, 2023

NIST’s grid of quantum islands could reveal secrets for powerful technologies November 18th, 2022

Photonics/Optics/Lasers

New microscope offers faster, high-resolution brain imaging: Enhanced two-photon microscopy method could reveal insights into neural dynamics and neurological diseases August 16th, 2024

Groundbreaking precision in single-molecule optoelectronics August 16th, 2024

Enhancing electron transfer for highly efficient upconversion: OLEDs Researchers elucidate the mechanisms of electron transfer in upconversion organic light-emitting diodes, resulting in improved efficiency August 16th, 2024

Single atoms show their true color July 5th, 2024

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




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project