Stimulated emission as a result of multiphoton interference

By performing an experiment on stimulated emission by two photons in the parametric amplification process and comparing it to a three-photon interference scheme, we present evidence in support of the idea that the underlying physics of stimulated emission is simply the constructive interference due to photon indistinguishability. So the observed signal enhancement upon the input of photons can be interpreted as a result of multiphoton interference of the input photons and the otherwise spontaneously emitted photon from the amplifier.

Four-photon interference with asymmetric beam splitters

Two experiments of four-photon interference are performed with two pairs of photons from parametric downconversion with the help of asymmetric beam splitters. The first experiment is a generalization of the Hong-Ou-Mandel interference effect to two pairs of photons while the second one utilizes this effect to demonstrate a four-photon de Broglie wavelength of lambda/4 by projection measurement.

Demonstration of temporal distinguishability in a four-photon state and a six-photon state

An experiment is performed to demonstrate the temporal distinguishability of a four-photon state and a six-photon state, both from parametric down-conversion. The experiment is based on a multiphoton interference scheme in a recently discovered projection measurement of a maximally entangled N-photon state. By measuring the visibility of the interference dip, we can distinguish the various scenarios in the temporal distribution of the pairs and, thus, quantitatively determine the degree of temporal distinguishability of a multiphoton state.

Efficient scheme for two-atom entanglement and quantum information processing in cavity QED

A scheme is proposed for the generation of two-atom maximally entangled states and realization of quantum logic gates and teleportation with cavity QED. The scheme does not require the transfer of quantum information between the atoms and cavity. In the scheme the cavity is only virtually excited and thus the requirement on the quality factor of the cavities is greatly loosened.