Showing posts with label Quantum Computers. Show all posts
Showing posts with label Quantum Computers. Show all posts

Daily Science Journal (Oct. 9, 2007) — Scientists at Florida State University's National High Magnetic Field Laboratory and the university's Department of Chemistry and Biochemistry have introduced a new material that could be to computers of the future what silicon is to the computers of today.

Crystal structure of the potassium-niobium-oxygen compound doped with chromium ions. Brown arrows show well-separated electron spins. The electromagnetic radiation used to control the spins is shown in black. (Credit: Image courtesy of Florida State University)

The material -- a compound made from the elements potassium, niobium and oxygen, along with chromium ions -- could provide a technological breakthrough that leads to the development of new quantum computing technologies. Quantum computers would harness the power of atoms and molecules to perform memory and processing tasks on a scale far beyond those of current computers.


"The field of quantum information technology is in its infancy, and our work is another step forward in this fascinating field," said Saritha Nellutla, a postdoctoral associate at the magnet lab and lead author of the paper published in Physical Review Letters.

Semiconductor technology is close to reaching its performance limit. Over the years, processors have shrunk to their current size, with the components of a computer chip more than 1,000 times smaller than the thickness of a human hair. At those very small scales, quantum effects -- behaviors in matter that occur at the atomic and subatomic levels -- can start playing a role. By exploiting those behaviors, scientists hope to take computing to the next level.

In current computers, the basic unit of information is the "bit," which can have a value of 0 or 1. In so-called quantum computers, which currently exist only in theory, the basic unit is the "qubit" (short for quantum bit). A qubit can have not only a value of 0 or 1, but also all kinds of combinations of 0 and 1 -- including 0 and 1 at the same time -- meaning quantum computers could perform certain kinds of calculations much more effectively than current ones.

How scientists realize the promise of the theoretical qubit is not clear. Various designs and paths have been proposed, and one very promising idea is to use tiny magnetic fields, called "spins." Spins are associated with electrons and various atomic nuclei.

Magnet lab scientists used high magnetic fields and microwave radiation to "operate" on the spins in the new material they developed to get an indication of how long the spin could be controlled. Based on their experiments, the material could enable 500 operations in 10 microseconds before losing its ability to retain information, making it a good candidate for a qubit.

Putting this spin to work would usher in a technological revolution, because the spin state of an electron, in addition to its charge, could be used to carry, manipulate and store information.

"This material is very promising," said Naresh Dalal, a professor of chemistry and biochemistry at FSU and one of the paper's authors. "But additional synthetic and magnetic characterization work is needed before it could be made suitable for use in a device."

Dalal also serves as an adviser to FSU chemistry graduate student Mekhala Pati, who created the material.

Adapted from materials provided by Florida State University.






Read the rest of this entry »

Daily Science Journal (Aug. 27, 2007) — Australian and French scientists have made another breakthrough in the technology that will drive next generation computers and teleportation.

The researchers have successfully superposed light beams, which produces a state that appears to be both on and off at once.

Light beams that are simultaneously on and off are vital for the next-generation super computers which should be faster than current computers based on bits, that are either on or off.

Previously, only smaller light particles had been superposed and the group has also proved a quantum physics theory known as Schrödinger's cat.


This theory, named after an Austrian physicist Erwin Schrödinger, proposed that a large object such as a cat could be simultaneously alive and dead.

Researchers from The University of Queensland and University of Paris South have published the latest breakthrough in the journal Nature.

UQ Centre for Quantum Computer Technology researcher Dr Hyunseok Jeong devised the scheme to generate and superpose the beams which was tested and proved by his French collaborators.

Dr Jeong said his group used special lasers, crystals, photon detectors, half-mirrors and other optical devices to generate and measure the superposition of light beams.

"It has been known to be extremely hard to generate Schrödinger cat states, particularly with traveling light," Dr Jeong said.

"Even though one could generate such Schrodinger cat states, it would be extremely hard to observe them because in a very short time, they would be reduced to either alive or dead states."

He said his group's research findings would help speed up the development of quantum information technologies such as quantum computers, quantum cryptography and quantum teleportation.

"Using Schrödinger cat states, quantum teleportation may be performed with nearly 100 percent success probability."

Adapted from materials provided by University of Queensland, via EurekAlert!, a service of AAAS.





Read the rest of this entry »

Daily Science Journal (Jun. 17, 2007) — Researchers at Delft University of Technology have succeeded in carrying out calculations with two quantum bits, the building blocks of a possible future quantum computer. The Delft researchers are publishing an article about this important step towards a workable quantum computer in this week's issue of Nature.

Superconducting rings on a chip. (Credit: TU Delft)

Quantum computers have superior qualities in comparison to the type of computers currently in use. If they are realised, then quantum computers will be able to carry out tasks that are beyond the abilities of all normal computers.


A quantum computer is based on the amazing properties of quantum systems. In these a quantum bit, also known as a qubit, exists in two states at the same time and the information from two qubits is entangled in a way that has no equivalent whatsoever in the normal world.

It is highly likely that workable quantum computers will need to be produced using existing manufacturing techniques from the chip industry. Working on this basis, scientists at Delft University of Technology are currently studying two types of qubits: one type makes use of tiny superconducting rings, and the other makes use of 'quantum dots'.

Now for the first time a 'controlled-NOT' calculation with two qubits has been realised with the superconducting rings. This is important because it allows any given quantum calculation to be realised.

The result was achieved by the PhD student Jelle Plantenberg in the team led by Kees Harmans and Hans Mooij. The research took place within the FOM (Dutch Foundation for Fundamental Research on Matter) concentration group for Solid State Quantum Information Processing.

Adapted from materials provided by Delft University of Technology, via EurekAlert!, a service of AAAS.





Read the rest of this entry »