Interactive: Cats and qubits

updated 10/4/2006 6:01:45 PM ET 2006-10-04T22:01:45

Beaming people in "Star Trek" fashion is still in the realms of science fiction, but physicists in Denmark have used weird quantum teleportation to transfer information from photons to atoms, bringing the dream of lightning-fast quantum computers closer to reality.

Scientists have previously teleported information about quantum states between photons or between atoms. But Professor Eugene Polzik and his team at the Niels Bohr Institute at Copenhagen University in Denmark have made a breakthrough by using both light and matter in the same teleportation experiment.

"It is one step further because for the first time it involves teleportation between light and matter, two different objects. One is the carrier of information, and the other one is the storage medium," Polzik explained in an interview on Wednesday.

The technique could be adapted for use in future quantum computers. Instead of storing information as magnetic bits on a hard drive, for example, the data could be stored as the quantum spin states of individual atoms, or "qubits." The information could then be transferred to light impulses for processing.

Polzik's experiment involved a macroscopic object — specifically, a cloud of about a trillion cesium atoms enclosed in a cell and held in place by a magnetic field. The researchers teleported the information over a distance of 20 inches (half a meter) but believe it can be extended further.

" Teleportation between two single atoms had been done two years ago by two teams, but this was done at a distance of a fraction of a millimeter," Polzik, of the Danish National Research Foundation Center for Quantum Optics, explained. "Our method allows teleportation to be taken over longer distances because it involves light as the carrier of entanglement."

What is teleportation?
Quantum teleportation is the transfer of a quantum state from one particle to another without a physical link. A quantum state would be a physical property of the particle, such as its  energy, motion or spin. Some scientists believe that manipulating the spin of subatomic particles — that is, their angular momentum — could lead to a whole new field of electronics dubbed "spintronics."

The teleportation technique relies on the process of entanglement, whereby the properties of two particles can be tied together even when they are far apart. By checking the state of one particle, the observer can know the state of the other particle as well.

Although teleportation is associated with the science-fiction series "Star Trek," no one is likely to be beamed anywhere soon. But the achievement of Polzik's team, in collaboration with the theorist Ignacio Cirac of the Max Planck Institute for Quantum Optics in Garching, Germany, marks an advancement in the field of quantum information and computers, which could transmit and process information in a way that was impossible before.

"It is really about teleporting information from one site to another site. Quantum information is different from classical information in the sense that it cannot be measured. It has much higher information capacity and it cannot be eavesdropped on. The transmission of quantum information can be made unconditionally secure," said Polzik, whose research is reported in Thursday's issue of the journal Nature.

Quantum computing would require manipulation of the information contained in the quantum states of particles.

"Creating entanglement is a very important step, but there are two more steps at least to perform teleportation. We have succeeded in making all three steps — that is entanglement, quantum measurement and quantum feedback," he added.

This report includes information from

Copyright 2012 Thomson Reuters. Click for restrictions.


Discussion comments


Most active discussions

  1. votes comments
  2. votes comments
  3. votes comments
  4. votes comments