Mach-Zehnder interferometer for a two-photon wave packet

Abstract

We propose an experiment that permits observation of the de Broglie two-photon wave packet behavior for a pair of photons, using a Mach-Zehnder interferometer. It is based on the use of pulsed lasers to generate pairs of photons via spontaneous parametric down-conversion and the post-selection of events. It differs from previous realizations by the use of a third time-correlated photon to engineer the state of the photons. The same technique can give us which-path information via an ''interaction-free'' experiment and can be used in other experiments on the foundations of quantum mechanics related to wave-particle duality and to nonlocality.

de Broglie wavelength reduction for a multiphoton wave packet

“…So far, only variations with the wavelength of the pump-beam, i.e. halving of the effective de Broglie wavelength (using one photon pair) have been observed [4,[9][10][11], consequently the idea presented here will allow for a test of a quantum effect not observed before, namely, a reduction of the multi-particle de Broglie wavelength below that of the generating source [7,12]. See reference [13], however, for the observation of a quartering of the joint phase of the internal degrees of freedom of four entangled ions in a trap.…”

“…The down-conversion source allowed them to abandon the non-linear beam-splitter in the input of their Young's double-slit setup, and a two-particle coincidence detection scheme allowed them to get rid of the second nonlinear beam mixer. Here, I want to present a modification to their approach (borrowing ideas from [5,6] and [7]) that should allow for the observation of a fourfold reduction of the de Broglie wavelength with currently available technology [6,8].…”

“…Another recent proposal [7] suggests to use a Mach-Zehnder layout and a projective measurement involving a third auxiliary photon (from a second down-conversion photon pair) in order to prepare state (1) for one photon pair inside the interferometer.…”

“…But both these approaches do not scale favourably for higher photon numbers, in the latter case [7] the use of auxiliary photons leads to extra channels and losses in the interferometer. In the former case of experiment [4] the momentum selection trick cannot be extended to higher photon numbers because multiple pump photons would be involved; this leads to a multiple product of the singlepair state mentioned above, i.e., in general to a state very different from the desired form (1).…”

A Mach-Zehnder Interferometry Method for the Measurement of Photonic State Squeezing in Quantum Cavities

“…A winner of the Nobel Prize, Serge Haroche, has presented an interesting non-demolition method for measuring Wigner function in a quantum cavity [12]. On the other hand, the Mach-Zehnder interferometry is applied to Bell's inequality [22,23], electronic Mach-Zehnder interferometer (MZI) [24], single and two photon interferometry [25,26], production and observation of Greenberger-Horne-Zeilinger entanglement [27], and optical amplification [28,29].…”