 |
|
Atom 'noise' may help design quantum computers
March 05, 2007As if building a computer out of rubidium atoms and laser beams weren't difficult enough, scientists sometimes have to work as if blindfolded: The quirks of quantum physics can cause correlations between the atoms to fade from view at crucial times.
What to do? Focus on the noise patterns. Building on earlier work by other groups, physicists at the National Institute of Standards and Technology (NIST) have found that images of "noise" in clouds of ultracold atoms trapped by lasers reveal hidden structural patterns, including spacing between atoms and cloud size.
The technique, described in the Feb. 23 issue of Physical Review Letters,* was demonstrated in an experiment to partition about 170,000 atoms in an "optical lattice," produced by intersecting laser beams that are seen by the atoms as an array of energy wells arranged like an egg carton. By loading just one atom into each well, for example, scientists can create the initial state of a hypothetical quantum computer using neutral atoms to store and process information.
The atoms first are cooled to form a Bose-Einstein condensate (BEC), a unique form of matter in which all the atoms are in the same quantum state and completely indistinguishable. The optical lattice lasers then are slowly turned on and the BEC undergoes a transformation in which the atoms space out evenly in the lattice. More intense light creates deeper wells until each atom settles into its own lattice well. But during this transition, scientists lose their capability to see and measure key quantum correlations among the atoms.
Key structures are visible, however, in composite images of the noise patterns, which reveal not only atom spacing but also cloud size and how much of the BEC has undergone the transition.
In the NIST experiments, the BEC was placed in an optical lattice at various laser intensities. The lattice was turned off, and scientists took pictures of the expanding cloud of atoms after 20 to 30 milliseconds. To identify and enhance the noise signal, scientists looked for identical bumps and wiggles in the images and made composites of about 60 images by identifying and overlaying matching patterns. Lead author Ian Spielman likens the technique to listening to a noisy ballroom: While it may be impossible to hear specific conversations, correlations in noise can show where people (or atoms) are located in relation to each other, and the volume of noise can indicate the size of the ballroom (or atomic cloud), Spielman says.
National Institute of Standards and Technology (NIST)
The atoms first are cooled to form a Bose-Einstein condensate (BEC), a unique form of matter in which all the atoms are in the same quantum state and completely indistinguishable. The optical lattice lasers then are slowly turned on and the BEC undergoes a transformation in which the atoms space out evenly in the lattice. More intense light creates deeper wells until each atom settles into its own lattice well. But during this transition, scientists lose their capability to see and measure key quantum correlations among the atoms.
Key structures are visible, however, in composite images of the noise patterns, which reveal not only atom spacing but also cloud size and how much of the BEC has undergone the transition.
In the NIST experiments, the BEC was placed in an optical lattice at various laser intensities. The lattice was turned off, and scientists took pictures of the expanding cloud of atoms after 20 to 30 milliseconds. To identify and enhance the noise signal, scientists looked for identical bumps and wiggles in the images and made composites of about 60 images by identifying and overlaying matching patterns. Lead author Ian Spielman likens the technique to listening to a noisy ballroom: While it may be impossible to hear specific conversations, correlations in noise can show where people (or atoms) are located in relation to each other, and the volume of noise can indicate the size of the ballroom (or atomic cloud), Spielman says.
National Institute of Standards and Technology (NIST)
Quantum Computers News and Current Quantum Computers Events RSSFast quantum computer building block created
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.
UCSB researchers make milestone discovery in quantum mechanics
Researchers at UC Santa Barbara have recently reached what they are calling a milestone in experimental quantum mechanics.
Physicists produce quantum-entangled images
Using a convenient and flexible method for creating twin light beams, researchers at the Joint Quantum Institute (JQI) of the Commerce Department's National Institute of Standards and Technology (NIST) and the University of Maryland have produced "quantum images," pairs of information-rich visual patterns whose features are "entangled," or inextricably linked by the laws of quantum physics.
Researchers untangle quantum quirk
Quantum computing has been hailed as the next leap forward for computers, promising to catapult memory capacity and processing speeds well beyond current limits. Several challenging problems need to be cracked, however, before the dream can be fully realized.
Weizmann Institute Scientists Find New 'Quasiparticles'
Weizmann Institute physicists have demonstrated, for the first time, the existence of 'quasiparticles' with one quarter the charge of an electron. This finding could be a first step toward creating exotic types of quantum computers that might be powerful, yet highly stable.
Oregon physicists don't flip spin but find possible electron switch
University of Oregon researchers trying to flip the spin of electrons with laser bursts lasting picoseconds (a trillionth of a second) instead found a way to manipulate and control the spin -- knowledge that may prove useful in a variety of new materials and technologies.
McCormick Researchers Take Step Toward Creating Quantum Computers
For now, full-fledged quantum computers are the stuff of science fiction - in last summer's blockbuster movie Transformers, the bad guys use quantum computing to break into the U.S. Army's secure files in just 10 seconds flat.
The future of computing -- carbon nanotubes and superconductors to replace the silicon chip
The future of computing is under the spotlight at the Institute of Physics' Condensed Matter and Materials Physics conference at the Royal Holloway College of the University of London on 26-28 March.
Physicists team up to learn how quantum mechanical states break down
Researchers at the US Department of Energy's Ames Laboratory, the University of California, Santa Barbara, and Microsoft Station Q have made significant advancements in understanding a fundamental problem of quantum mechanics -- one that is blocking efforts to develop practical quantum computers with processing speeds far superior to conventional computers. Their respective theoretical and experimental studies investigate how microscopic objects lose their quantum-mechanical properties through interactions with the environment.
Future 'quantum computers' will offer increased efficiency... and risks
An unusual observation in a University of Central Florida physics lab may lead to a new generation of "Quantum Computers" that will render today's computer and credit card encryption technology obsolete.
More Quantum Computers News Articles
 | The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography by Simon Singh People love secrets. Ever since the first word was written, humans have sent coded messages to each other. In The Code Book, Simon Singh, author of the bestselling Fermat's Enigma, offers a peek into the world of cryptography and codes, from ancient texts through computer encryption. Singh's compelling history is woven through with stories of how codes and ciphers have played a vital role in... |
 | Quantum Computer Science: An Introduction by N. David Mermin In the 1990's it was realized that quantum physics has some spectacular applications in computer science. This book is a concise introduction to quantum computation, developing the basic elements of this new branch of computational theory without assuming any background in physics. It begins with an introduction to the quantum theory from a computer-science perspective. It illustrates the... |
 | Quantum Computation and Quantum Information by Michael A. Nielsen, Isaac L. Chuang In this first comprehensive introduction to the main ideas and techniques of quantum computation and information, Michael Nielsen and Isaac Chuang ask the question: What are the ultimate physical limits to computation and communication? They detail such remarkable effects as fast quantum algorithms, quantum teleportation, quantum cryptography and quantum error correction. A wealth of accompanying... |
 | An Introduction to Quantum Computing by Phillip Kaye, Raymond Laflamme, Michele Mosca This concise, accessible text provides a thorough introduction to quantum computing - an exciting emergent field at the interface of the computer, engineering, mathematical and physical sciences. Aimed at advanced undergraduate and beginning graduate students in these disciplines, the text is technically detailed and is clearly illustrated throughout with diagrams and exercises. Some prior... |
 | Programming the Universe: A Quantum Computer Scientist Takes on the Cosmos by Seth Lloyd Is the universe actually a giant quantum computer? According to Seth Lloyd, the answer is yes. All interactions between particles in the universe, Lloyd explains, convey not only energy but also information–in other words, particles not only collide, they compute. What is the entire universe computing, ultimately? “Its own dynamical evolution,” he says. “As the computation... |
 | Understanding Molecular Simulation (Computational Science Series, Vol 1) by Daan Frenkel, B. Smit Understanding Molecular Simulation: From Algorithms to Applications explains the physics behind the "recipes" of molecular simulation for materials science. Computer simulators are continuously confronted with questions concerning the choice of a particular technique for a given application. A wide variety of tools exist, so the choice of technique requires a good understanding of the basic... |
 | Practical Statecharts in C/C++: Quantum Programming for Embedded Systems with CDROM by Miro Samek 'Downright revolutionary... the title is a major understatement... 'Quantum Programming' may ultimately change the way embedded software is designed.' -- Michael Barr, Editor-in-Chief, Embedded Systems Programming magazine (Click herePractical Statecharts in C/C++ illustrates how to efficiently code statecharts directly in C/C++. You get a lightweight alternative to CASE tools that permits you to... |
 | Contemporary College Physics, Third Edition, 2001 Update w/ updated CD-ROM by Edwin R Jones, Richard L. Childers This Update of Jones/Childers, CONTEMPORARY COLLEGE PHYSICS, Third Edition adds new biomedical applications and improved technology to the copyright 1999 third edition. Since all exercises from the 1999 edition are retained, the 1999 print supplements will work for the 2001 Update. Jones/Childers 3/e features a strong emphasis on problem solving and a tutorial CD-ROM with multimedia and... |
 | The Large, the Small and the Human Mind by Roger Penrose Will quantum physics let us reduce consciousness to computation? Roger Penrose says "no" with great force and eloquence in The Large, the Small, and the Human Mind. Prepared as a series of three lectures in Cambridge's Tanner Series on Human Values, the material is both meticulously thought out and informally presented, including many illustrations by Penrose and others. For publication, the... |
| Student Solutions Manual for Quantum Chemistry and Spectroscopy for Quantum Chemistry and Spectroscopy with Spartan Student Physical Chemistry Software by Tom Engel |
| © 2008 BrightSurf.com |