Abstract

Existing single-photon sources can be classified as either isolated quantum systems or emitters of photon-pairs where the detection of one photon (herald) indicates the existence of the second photon (signal). The most widely used two-photon emitter is based on parametric down-conversion (PDC) emitting a nearly pure coherent (slightly squeezed) state of photon pairs [1,2]. In contrast to nonlinear insulating crystals used for PDC, semiconductors allow manipulation of free charge carriers, and thus more efficient photon pair generation can be exhibited, involving the recombination of charge carriers. The recently observed process of semiconductor two-photon emission (TPE) [3] provides an efficient source of photon pairs with Poissonian pair statistics similar to PDC, however in a mixed state. The non-classical nature of PDC heralded photons was previously demonstrated by their sub-Poissonian second-order correlation g⁽²⁾(0)<1 [4], although the heralded states themselves were not defined in closed form. Another important criterion of antibunching g⁽²⁾(0)< g⁽²⁾(τ) was shown experimentally for discrete time bins [1], however the theoretical model for heralded photon states and their antibunched statistics was not presented before.

© 2009 IEEE