Interference between entangled photon states in space and time

David A. Branning, Warren P. Grice, Reinhard K. Erdmann +1 more

We give a detailed account of a recently introduced technique to suppress distinguishing information in the space-time component of the state vector of a pair of photons. The method works by creating interference between two possible ways for each photon to occupy any given space-time mode. Under certain conditions, this technique also allows the preparation of the two photons in a highly entangled space-time state.

Ahmad Salmanogli

Chang Liu, J. F. Chen, Shanchao Zhang +5 more

F. Devaux, A. Mosset, Paul‐Antoine Moreau +1 more

For the first time, experiments show 2D spatial as well as temporal interference of pairs of entangled photons with enormous dimensionality, setting the stage for complex quantum information protocols that depend on space and time.

Yoon-Ho Kim, S. P. Kulik, Yanhua H. Shih

Two spatially separated type-I nonlinear crystals are pumped by femtosecond laser pulses to create entangled photon pairs in the process of spontaneous parametric down-conversion. The two-photon entangled state exhibits high-visibility quantum interference for both polarization and space-time variables without the need of stringent spectral postselection by using narrow-band filters. The visibility is insensitive to the thickness of the crystals, unlike in the case of pulse pumped type-II parametric down-conversion; therefore the intensity can be easily increased by using thick nonlinear crystals. This method will be indispensable in experiments that require a pulsed source of entangled photon pairs, such as generation of multiphoton entangled states, quantum teleportation, and quantum communications.

Iu. L. Dobrynin, V. V. Lomonosov