Editor's Summary
15 March 2007
Life and death of a photon
In a microscopic quantum system under continuous observation, it should be possible to detect sudden changes or jumps in the quantum state of trapped particles. This has been done with particles with mass, like electrons and molecules, but it had not been possible for massless light quanta, since standard photodetectors absorb light, prohibiting repeated measurements of the same photon. This obstacle has now been overcome using a stream of non-absorbing atoms to probe microwave photons stored in a superconducting cavity. Sequences of hundreds of atoms, highly correlated in the same state, are interrupted by sudden state switchings. These telegraphic signals record the birth, life and death of individual photons. This work comes close to realizing Einstein's dream of a single photon stored in a box for times in the second range and weighed by a sensitive scale — a stream of atoms in this experiment.
News and Views: Quantum physics: Total surveillance
Trapped by mirrors, a photon can be monitored from birth to death by a stream of passing atoms. The technique could also be used to entangle the quantum states of many atoms — a possible boon for quantum computing.
Ferdinand Schmidt-Kaler
doi:10.1038/446275a
Letter: Quantum jumps of light recording the birth and death of a photon in a cavity
Sébastien Gleyzes, Stefan Kuhr, Christine Guerlin, Julien Bernu, Samuel Deléglise, Ulrich Busk Hoff, Michel Brune, Jean-Michel Raimond & Serge Haroche
doi:10.1038/nature05589