Multiphoton interference in quantum Fourier transform circuits and applications to quantum metrology

TL;DR

This paper introduces a technique for constructing quantum Fourier transform interferometers using path and polarization modes, demonstrating multi-photon interference effects and enhanced phase sensitivity for quantum metrology.

Contribution

A novel method for building QFT interferometers with combined path and polarization modes, enabling observation of multi-photon interference and phase supersensitivity.

Findings

Observed generalized Hong-Ou-Mandel effect with up to four photons

Demonstrated deterministic optical phase supersensitivity

Utilized number-path entanglement in QFT interferometers

Abstract

Quantum Fourier transforms (QFT) have gained increased attention with the rise of quantum walks, boson sampling, and quantum metrology. Here we present and demonstrate a general technique that simplifies the construction of QFT interferometers using both path and polarization modes. On that basis, we first observed the generalized Hong-Ou-Mandel effect with up to four photons. Furthermore, we directly exploited number-path entanglement generated in these QFT interferometers and demonstrated optical phase supersensitivities deterministically.