Optical Fibers May Carry Quantum Information

Optical Fibers May Carry Quantum Information

5 February 2013

Optical fibers may be able to transport quantum information, according to a new study by Austrian physicists.

University of Innsbruck researchers Tracy Northup and Rainer Blatt have directly transferred the quantum information of an atom onto a particle of light, theoretically enabling information to be transported to a distant atom via optical fibers.

The future quantum computers would be able to perform some computational tasks at far greater speed than conventional computers. One of the most promising technologies for building such a computer involves single atoms confined in ion traps and manipulated with lasers. Today we can perform successful computations with atoms but we are lacking appropriate interfaces with which quantum information can be transferred over optical channels from one computer to another, Andreas Stute of the university's Institute for Experimental Physics explains. Building such interfaces is difficult because quantum information cannot simply be copied but has to be transferred onto individual photons and transported over an optical fiber link to a distant computing site.

In the study, which was published in Nature Photonics, the Innsbruck scientists trapped a calcium ion in an ion trap and placed it between two highly reflective mirrors. They used a laser to write the desired quantum information onto the electronic states of the atom and then excited the atom with a second laser for it to emit a photon. The atom's quantum information was then written onto the polarized state of the photon, which was stored between the mirrors until it moved out of the trap into the optical fiber.

The scientists believe that quantum information stored in the photon could be transported to a distant quantum computer and through the use of the same technique to be written back onto an atom.