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.
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.
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
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
Announcements
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
Groundbreaking precision in single-molecule optoelectronics August 16th, 2024
Single atoms show their true color July 5th, 2024
The latest news from around the world, FREE | ||
Premium Products | ||
Only the news you want to read!
Learn More |
||
Full-service, expert consulting
Learn More |
||