Synopsis: Single photon emission in the next dimension

Single photon emission is normally only observed in systems, such as atoms, that are quantum confined in all directions. Now, scientists have shown that carbon nanotubes, which are quasi-one-dimensional materials, can also act as single photon emitters.
Synopsis figure

A light source that emits only one photon at a time would be an invaluable tool for quantum optics and quantum computing. Quasi-zero-dimensional systems such as atoms, nitrogen vacancies in diamond, and quantum dots emit photons one by one when excited by laser light. The reason for this is that when charge carriers are strongly confined, the multiple excited states necessary for emission of two photons do not exist.

In materials that are extended in one or more dimensions, multiple excited states (namely, electron-hole pairs) can coexist and these materials tend to be poor candidates for single-photon emitters. However, in the 27 May 2008 issue of Physical Review Letters, Alexander Högele, Christopher Galland, Martin Winger, and Ataç Imamo?lu report that at low temperatures, semiconducting carbon nanotubes act as single-photon emitters when excited by a laser beam.

The unexpected finding is due to a combination of effects that prohibit double occupancy of excited states: the electron-hole pairs are highly localized and Auger processes (in which electron-hole pairs recombine without photon emission) are strong. Fewer than 1 in 20 events are reported to be multiphoton emissions, making carbon nanotubes promising single-photon sources. - Daniel Ucko


Announcements

More Announcements »

Subject Areas

OpticsNanophysics

Previous Synopsis

Next Synopsis

Related Articles

Synopsis: Position Detector Approaches the Heisenberg Limit
Quantum Physics

Synopsis: Position Detector Approaches the Heisenberg Limit

The light field from a microcavity can be used to measure the displacement of a thin bar with an uncertainty that is close to the Heisenberg limit. Read More »

Viewpoint: Next Generation Clock Networks
Atomic and Molecular Physics

Viewpoint: Next Generation Clock Networks

Free-space laser links have been used to synchronize optical clocks with an unprecedented uncertainty of femtoseconds. Read More »

Focus: How to Make an Intense Gamma-Ray Beam
Optics

Focus: How to Make an Intense Gamma-Ray Beam

Computer simulations show that blasting plastic with strong laser pulses could produce gamma rays with unprecedented intensity, good for fundamental physics experiments and possibly cancer treatments. Read More »

More Articles