Optical Precursor of a Single Photon
Abstract
We report the direct observation of optical precursors of heralded single photons with step- and square-modulated wave packets passing through cold atoms. Using electromagnetically induced transparency and the slow-light effect, we separate the single-photon precursor, which always travels at the speed of light in vacuum, from its delayed main wave packet. In the two-level superluminal medium, our result suggests that the causality holds for a single photon.
- Publication:
-
Physical Review Letters
- Pub Date:
- June 2011
- DOI:
- Bibcode:
- 2011PhRvL.106x3602Z
- Keywords:
-
- 42.50.Gy;
- 32.80.Qk;
- 42.50.Dv;
- Effects of atomic coherence on propagation absorption and amplification of light;
- electromagnetically induced transparency and absorption;
- Coherent control of atomic interactions with photons;
- Nonclassical states of the electromagnetic field including entangled photon states;
- quantum state engineering and measurements