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


Features

More Features »

Announcements

More Announcements »

Subject Areas

OpticsNanophysics

Previous Synopsis

Next Synopsis

Related Articles

Synopsis: Straining After Quantum Dots
Semiconductor Physics

Synopsis: Straining After Quantum Dots

The positions of quantum dots inside a microstructure can be determined by monitoring how an applied strain affects the dots’ photoluminescence.   Read More »

Viewpoint: A New Twist on Relativistic Electron Vortices
Nanophysics

Viewpoint: A New Twist on Relativistic Electron Vortices

Two studies explore the properties of vortices formed by electrons that travel at relativistic speeds. Read More »

Synopsis: A Neat Way to Slow Down Light
Optics

Synopsis: A Neat Way to Slow Down Light

A new technique slows down light in a crystal by simply shining a laser on it and varying an applied voltage. Read More »

More Articles