Abstract

We present an entanglement swapping experiment realized for the first time with independent photon pairs created in continuous wave (CW) mode [1]. Pairs of energy-time entangled photons (A1-A2 and B1-B2) are emitted by autonomous sources at telecom wavelength (1560nm). Two photons, one from each pair (Al, Bl), are combined on a beamsplitter (BS) and projected via a joint measurement onto one of the four Bell states (BSM), projecting the two remaining photons A2 and B2 in an entangled state albeit they never interacted or share any common elements (Figl). The novel aspect of our approach is the fact that the required synchronization of the photons at the BS is obtained by the temporal resolution of the single photon detectors. To this end, the coherence time of the created photon pairs has to be longer than the temporal resolution of the detectors. Our experiment represents an implementation of the entanglement swapping scheme, which until now has never been realized with CW sources as originally proposed [2]. This enables the use of independent diode lasers in C W mode without any need for synchronization.

© 2007 IEEE