Two-photon interference without bunching two photons

Kim, Y H

We report an interference experiment in which the two-photon entangled state interference cannot be pictured in terms of the overlap and bunching of two individual photons on a beamsplitter. We also demonstrate that two-photon interference, or photon bunching effect on a beamsplitter, does not occur if the two-photon Feynman amplitudes are distinguishable, even though individual photons do overlap on a beamsplitter. Therefore, two-photon interference cannot be viewed as interference of two individual photons, rather it should be viewed as two-photon or biphoton interfering with itself. The results may also be useful for studying decoherence management in entangled two-qubit systems as we observe near complete restoration of quantum interference after the qubit pairs, generated by a femtosecond laser pulse, went through certain birefringent elements.

Jianbin Liu, Yu Zhou, Huaibin Zheng +3 more

Ping‐Xing Chen

The discovery of photon bunching effect is an important milestone of quantum optics.The attempt to explain it leads to the development of the techniques in quantum optics.Nowadays,it′s thought that the physics behind the photon bunching effect in the second-order coherence is two-photon interference.This paper shows that there are similar generalized bunching effects in higher-order coherence.We also claim that the generalized photon bunching effect is a result of multi-photon interference due to indistinguishability of photons.In some typical optical circuit,N-photon interference can let the enhancement factor be up to N!.

Frank King, Margaret Trias, Martin Ligare

Paul G. Kwiat

Z. Y. Ou, June‐Koo Kevin Rhee, L. J. Wang

A number of multiphoton interference schemes involving independent fields from parametric down-conversion are analyzed. They include fourth-order (two-photon) interference between two fields from two independent parametric down-conversion processes, interference with two independent single photon Fock states (produced by gated parametric down-conversion), and quantum state teleportation and entanglement swapping. It is shown that the visibility in these interference experiments is related to a quantity that is responsible for the photon bunching effect in one of the fields (signal or idler) from the parametric down-conversion process. Besides the two-photon interference schemes, a four-photon interference scheme is discussed where we consider four-photon partition at a beamsplitter. It is found that probability distribution of the partition is dramatically changed by four-photon interference of six paths and the four-photon effect also depends on the same quantity responsible for photon bunching. We will discuss the difference between two-photon interference and four-photon interference.