Generalized Multiphoton Quantum Interference

Max Tillmann,Barry C Sanders,Philip Walther,Alexander Szameit,Hubert De Guise,Sarah E Stoeckl,Si-Hui Tan,Stefan Nolte,René Heilmann

doi:10.1103/physrevx.5.041015

Abstract

Non-classical interference of photons lies at the heart of optical quantum information processing. This effect is exploited in universal quantum gates as well as in purpose-built quantum computers that solve the BosonSampling problem. Although non-classical interference is often associated with perfectly indistinguishable photons this only represents the degenerate case, hard to achieve under realistic experimental conditions. Here we exploit tunable distinguishability to reveal the full spectrum of multi-photon non-classical interference. This we investigate in theory and experiment by controlling the delay times of three photons injected into an integrated interferometric network. We derive the entire coincidence landscape and identify transition matrix immanants as ideally suited functions to describe the generalized case of input photons with arbitrary distinguishability. We introduce a compact description by utilizing a natural basis which decouples the input state from the interferometric network, thereby providing a useful tool for even larger photon numbers.

Highlights

The recent development of quantum photonics technology [1] allows experiments using a growing number of photons and large, complex interferometric networks
We introduce a compact description by utilizing a natural basis that decouples the input state from the interferometric network, thereby providing a useful tool for even larger photon numbers
We present a novel analysis of multiphoton quantum interference revealing the full permutational spectrum of input states with arbitrary distinguishability

Summary

Introduction

The recent development of quantum photonics technology [1] allows experiments using a growing number of photons and large, complex interferometric networks. Manipulating such large Hilbert spaces requires well-adapted tools in both theory and experiment. The objective of this paper is to show how controllable delays in multimode coincidence experiments are related to the interference of photons of controllable partial distinguishability. This is done by presenting a novel description for the nonclassical interference of multiple photons of arbitrary distinguishability propagating through arbitrary

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Conclusion