Synopsis: Out of many atoms, one photon

A gas of excited-state atoms could perform as a single-photon detector.
Synopsis figure
J. Honer, Phys. Rev. Lett. (2011)

Devices that count discrete quanta of light could be the building blocks of sophisticated quantum circuits. Most such counters based on single atoms register a photon only half the time, but in a paper appearing in Physical Review Letters, Jens Honer at the University of Stuttgart, Germany, and his colleagues propose a theoretical multi-atom system that could do the job with a nearly 100% success rate.

Honer et al.’s idea takes advantage of interactions between Rydberg atoms confined to a small trap. In a Rydberg atom, at least one valence electron is in a highly excited state, circling the nucleus with a large radius that mimics a classical orbit. These excited state atoms interact strongly with one another, such that one Rydberg atom in a trap can block other atoms from being excited—an effect called Rydberg blockade.

Honer et al. consider N atoms in a trap, which behave as a sort of superatom. The superatom has N excited states, with one Rydberg excitation collectively shared among the N atoms. Only one of these excited states interacts with light like a two-level system, while N-1 states remain dark. By introducing a second light field that causes dephasing, Honer et al. show that with large fidelity the superatom ends up in one of these N-1 dark states, and consequently greatly enhances the chance of photon absorption. At the same time the Rydberg blockade prevents the absorption of multiple photons within one such atom trap.

A series of these atom trap devices could, according to Horner et al., be used to count the photons in a few-photon light stream. – Jessica Thomas


Features

More Features »

Announcements

More Announcements »

Subject Areas

Atomic and Molecular Physics

Previous Synopsis

Quantum Information

Pointing toward stability

Read More »

Next Synopsis

Related Articles

Viewpoint: A Diatomic Molecule is One Atom too Few
Atomic and Molecular Physics

Viewpoint: A Diatomic Molecule is One Atom too Few

The successful laser cooling of a triatomic molecule paves the way towards the study of ultracold polyatomic molecules. Read More »

Viewpoint: Atom Interferometers Warm Up
Atomic and Molecular Physics

Viewpoint: Atom Interferometers Warm Up

Researchers have demonstrated an atom interferometer based on a warm vapor, rather than on a cold atomic gas. Read More »

Viewpoint: Electron Pulses Made Faster Than Atomic Motions
Atomic and Molecular Physics

Viewpoint: Electron Pulses Made Faster Than Atomic Motions

Electron pulses have shattered the 10-femtosecond barrier at which essentially all atomic motion is frozen in materials. Read More »

More Articles