Synopsis: Nanofiber Optical Memory

Light signals propagating down an ultrathin fiber can be temporarily stored in a cloud of cold atoms surrounding the fiber.
Synopsis figure
Julia Fraud/Laboratoire Kastler Brossel

An atomic gas can serve as a memory for the quantum state of a photon. Such a memory would make it easier to use the photon’s quantum properties for quantum communications or computing. But controlling a photon beam is easiest if it is trapped in an optical fiber. A group led by Julien Laurat from the Kastler Brossel Laboratory at the Pierre and Marie Curie University (UPMC), France, showed that a cloud of cold atoms surrounding an ultrathin fiber can store light propagating along the fiber.

Shining a bright laser on atoms can cancel their absorption at a different frequency. This electromagnetically induced transparency (EIT) can alter the propagation of a weaker “signal” beam at that frequency. But exploiting these effects in information-processing schemes requires sending the signal light to specific locations, which is clumsy for beams traveling in free space, as in most current schemes.

For easier routing, the researchers manipulated a beam of single photons without extracting it from an optical fiber. Their fiber included a short section whose 400-nanometer diameter squeezed about 40% of the traveling light energy into an evanescent field just outside the fiber. The team released a trapped low-temperature cloud of cesium atoms in this region and shone a second laser on it to create EIT. The atoms dramatically slowed the light in the fiber. By briefly dimming the control light, the team stored the light signal for microseconds as a collective state of the atoms. Although the current setup recovered only 10% of the stored signal, that signal is already 20 times larger than the background noise.

This research is published in Physical Review Letters.

–Don Monroe


More Features »


More Announcements »

Subject Areas

Quantum InformationOptics

Previous Synopsis

Next Synopsis


Quakes in Neutron Stars

Read More »

Related Articles

Viewpoint: Seeing Scrambled Spins
Atomic and Molecular Physics

Viewpoint: Seeing Scrambled Spins

Two experimental groups have taken a step towards observing the “scrambling” of information that occurs as a many-body quantum system thermalizes.   Read More »

Focus: <i>Image</i>—Cooperating Lasers Make Topological Defects
Nonlinear Dynamics

Focus: Image—Cooperating Lasers Make Topological Defects

A circle of interacting lasers is a new model system for exploring topological defects, disordered structures that show up in a wide variety of seemingly unrelated systems. Read More »

Viewpoint: Type-II Dirac Fermions Spotted
Quantum Information

Viewpoint: Type-II Dirac Fermions Spotted

Three separate groups report experimental evidence of novel type-II Dirac quasiparticles, suggesting possible applications in future quantum technology. Read More »

More Articles