 |
|
Photon-transistors for the supercomputers of the future
August 27, 2007Scientist from the Niels Bohr Institute at University of Copenhagen and from Harvard University have worked out a new theory which describe how the necessary transistors for the quantum computers of the future may be created. The research has just been published in the scientific journal Nature Physics.
Researchers dream of quantum computers. Incredibly fast super computers which can solve such extremely complicated tasks that it will revolutionise the application possibilities. But there are some serious difficulties. One of them is the transistors, which are the systems that process the signals.
Today the signal is an electrical current. For a quantum computer the signal can be an optical one, and it works using a single photon which is the smallest component of light.
"To work, the photons have to meet and "talk", and the photons very rarely interact together" says Anders Søndberg Sørensen who is a Quantum Physicist at the Niels Bohr Institute at Copenhagen University. He explains that light does not function like in Star Wars, where the people fight with light sabres and can cross swords with the light. That is pure fiction and can't happen. When two rays of light meet and cross, the two lights go right through each other. That is called linear optics.
What he wants to do with the light is non-linear optics. That means that the photons in the light collide with each other and can affect each other. This is very difficult to do in practice. Photons are so small that one could never hit one with the other. Unless one can control them - and it is this Anders Sørensen has developed a theory about.
Light collisions at the quantum level
Instead of shooting two photons at each other from different directions and trying to get them to hit each other, he wants to use an atom as an intermediary. The atom can only absorb one photon (such are the laws of physics). If you now direct two photons towards the atom it happens that they will collide on the atom. It is exactly what he wants.
The atom is however very small and difficult to hit. So the photons have to be focussed very precisely. In a previous experiment researchers had discovered that microwaves could be focussed on an atom via a superconducting nano-wire. They got the idea that the same could happen with visible light.
The theoretical model shows that it works. The atom is brought close to the nanowire. Two photons are sent towards the atom and when they hit it an interaction occurs between them, where one imparts information to the other. The information is sent in bits which are either a one or zero digit, and the order of digits produces the message. (Today we can send information via an optic cable and each bit is made up of millions of photons.) In quantum optics each bit is just one photon. The photon has now received its message and the signal continues on its way. It is a step on the way to building a photon-transistor for a quantum computer.
University of Copenhagen
"To work, the photons have to meet and "talk", and the photons very rarely interact together" says Anders Søndberg Sørensen who is a Quantum Physicist at the Niels Bohr Institute at Copenhagen University. He explains that light does not function like in Star Wars, where the people fight with light sabres and can cross swords with the light. That is pure fiction and can't happen. When two rays of light meet and cross, the two lights go right through each other. That is called linear optics.
What he wants to do with the light is non-linear optics. That means that the photons in the light collide with each other and can affect each other. This is very difficult to do in practice. Photons are so small that one could never hit one with the other. Unless one can control them - and it is this Anders Sørensen has developed a theory about.
Light collisions at the quantum level
Instead of shooting two photons at each other from different directions and trying to get them to hit each other, he wants to use an atom as an intermediary. The atom can only absorb one photon (such are the laws of physics). If you now direct two photons towards the atom it happens that they will collide on the atom. It is exactly what he wants.
The atom is however very small and difficult to hit. So the photons have to be focussed very precisely. In a previous experiment researchers had discovered that microwaves could be focussed on an atom via a superconducting nano-wire. They got the idea that the same could happen with visible light.
The theoretical model shows that it works. The atom is brought close to the nanowire. Two photons are sent towards the atom and when they hit it an interaction occurs between them, where one imparts information to the other. The information is sent in bits which are either a one or zero digit, and the order of digits produces the message. (Today we can send information via an optic cable and each bit is made up of millions of photons.) In quantum optics each bit is just one photon. The photon has now received its message and the signal continues on its way. It is a step on the way to building a photon-transistor for a quantum computer.
University of Copenhagen
Photons Current Events and Photons News RSSImproved spectrometer based on nonlinear optics
Scientists at Stanford University and Japan's National Institute of Informatics have created a new highly sensitive infrared spectrometer.
Super-Tough Sunshield to Fly on the James Webb Space Telescope
Imagine sunglasses that can withstand the severe cold and heat of space, a barrage of radiation and high-speed impacts from small space debris. They don't exist, but Northrop Grumman engineers have created a Sunshield for NASA's James Webb Space Telescope that can withstand all of those elements. The space telescope needs a Sunshield to block heat from the sun so its cameras and instruments can operate properly a million miles from the Earth, when it launches in 2013.
First gamma-ray-only pulsar observation opens new window on stellar evolution
About three times a second, a 10,000-year-old stellar corpse sweeps a beam of gamma-rays toward Earth.
NASA'S Fermi Telescope Discovers First Gamma-Ray-Only Pulsar
About three times a second, a 10,000-year-old stellar corpse sweeps a beam of gamma-rays toward Earth. Discovered by NASA's Fermi Gamma-ray Space Telescope, the object, called a pulsar, is the first one known that only "blinks" in gamma rays.
U.Va. Engineers Aim to Solve 'Burning' Computer Problem
f you've balanced a laptop computer on your lap lately, you probably noticed a burning sensation. That's because ever-increasing processing speeds are creating more and more heat, which has to go somewhere -- in this case, into your lap.
Scientists Detect Cosmic 'Dark Flow' Across Billions of Light Years
Using data from NASA's Wilkinson Microwave Anisotropy Probe (WMAP), scientists have identified an unexpected motion in distant galaxy clusters. The cause, they suggest, is the gravitational attraction of matter that lies beyond the observable universe.
BOSS: the Baryon Oscillation Spectroscopic Survey
The Sloan Digital Sky Survey (SDSS) uses a 2.5-meter telescope with a wider field of view than any other large telescope, located on a mountaintop in New Mexico called Apache Point and devoted solely to mapping the universe.
U.S. Air Force Technology Helps Scientists Understand Plant Root Function
The McClellan Nuclear Radiation Center (MNRC) in Sacramento, CA was developed by the U.S. Air Force to detect corrosion and defects in aircraft structure using an imaging technique called neutron radiography. This technique is currently helping soil scientists understand the function of plant roots and their uptake of water and nutrients.
GLAST Observatory renamed for Fermi, reveals entire gamma-ray sky
The U.S. Department of Energy (DOE) and NASA announced today that the Gamma-Ray Large Area Space Telescope (GLAST) has revealed its first all-sky map in gamma rays.
Light touch: Controlling the behavior of quantum dots
Researchers from the National Institute of Standards and Technology (NIST) and the Joint Quantum Institute (JQI), a collaborative center of the University of Maryland and NIST, have reported a new way to fine-tune the light coming from quantum dots by manipulating them with pairs of lasers.
More Photons Current Events and Photons News Articles
 | Exploring the Quantum: Atoms, Cavities, and Photons (Oxford Graduate Texts) by Serge Haroche, Jean-Michel Raimond The counter-intuitive aspects of quantum physics have been for long illustrated by thought experiments, from Einstein's photon box to Schrodinger's cat. These experiments have now become real, with single particles--electrons, atoms or photons--directly unveiling the weird features of the quantum. State superpositions, entanglement and complementarity define a novel quantum logic which can be... |
 | Photons and Atoms - Introduction to Quantum Electrodynamics (Wiley Professional) by Claude Cohen-Tannoudji, Jacques Dupont-Roc, Gilbert Grynberg Photons and Atoms Photons and Atoms: Introduction to Quantum Electrodynamics provides the necessary background to understand the various physical processes associated with photon-atom interactions. It starts with elementary quantum theory and classical electrodynamics and progresses to more advanced approaches. A critical comparison is made between these different, although equivalent,... |
 | Realistic Image Synthesis Using Photon Mapping by Henrik Wann Jensen The creation of realistic three-dimensional images is central to computer graphics. Photon mapping, an extension of ray tracing, makes it possible to efficiently simulate global illumination in complex scenes. Photon mapping can simulate caustics (focused light, such as shimmering waves at the bottom of a swimming pool), diffuse inter-reflections (for example, the bleeding of coloured light from... |
 | Photon Transfer (SPIE Press Monograph Vol. PM170) by James R. Janesick Photon Transfer is designed for a wide audience--from the novice to the advanced user already familiar with the method. For first-time users, the book's primary purpose is to give sufficient guidelines to accurately generate, calibrate, and understand imaging data products through the photon transfer method. The book contains more than 230 figures that present experimental CCD and CMOS data... |
 | Vision Science: Photons to Phenomenology by Stephen E. Palmer This book revolutionizes how vision can be taught to undergraduate and graduate students in cognitive science, psychology, and optometry. It is the first comprehensive textbook on vision to reflect the integrated computational approach of modern research scientists. This new interdisciplinary approach, called "vision science," integrates psychological, computational, and neuroscientific... |
 | Atom-Photon Interactions: Basic Processes and Applications (Wiley Science Paperback Series) by Claude Cohen-Tannoudji, Jacques Dupont-Roc, Gilbert Grynberg Atom-Photon Interactions: Basic Processes and Applications allows the reader to master various aspects of the physics of the interaction between light and matter. It is devoted to the study of the interactions between photons and atoms in atomic and molecular physics, quantum optics, and laser physics. The elementary processes in which photons are emitted, absorbed, scattered, or exchanged... |
 | Adaptive Wavefront Correction in Two-photon Microscopy: Coherence-Gated Wavefront Sensing by Markus Rückel The focus of a two-photon microscope is often degraded by inhomogeneities in therefractive index within biological specimens. In this book it is shown for variousspecimens, even for living zebrafish, that the resolution and the fluorescence signal of atwo-photon microscope can be substantially improved by using adaptive optics, i.e.wavefront correction based on coherence-gated wavefront sensing... |
| Time-Correlated Single Photon Counting by Desmond V. O'Connor, David Phillips | |
 | Interaction of Photons and Neutrons With Matter: An Introduction(2nd Edition) by Sow-Hsin Chen; Michael Kotlarchyk This invaluable book is based on lecture notes developed for a one-semester graduate course entitled Interaction of Radiation with Matter , taught in the Department of Nuclear Science and Engineering at the Massachusetts Institute of Technology. The main objective of the course is to teach enough quantum and classical radiation theory to allow students in engineering and the applied sciences to... |
| Thieves Of Light (Photon : the Ultimate Game on Planet Earth) by Michael Hudson |
| © 2008 BrightSurf.com |