Heralding two- and four-photon path entanglement on chip

TL;DR

This paper demonstrates on-chip heralded generation of multiphoton path-entangled states, such as NOON states, enabling phase superresolution and robustness for quantum metrology applications.

Contribution

It introduces a reconfigurable integrated waveguide device for heralded multiphoton entanglement generation, advancing on-chip quantum metrology capabilities.

Findings

Successful generation of two- and four-photon NOON states on chip

Achieved phase superresolution with heralded states

Demonstrated robustness to photon loss in realistic devices

Abstract

Generating quantum entanglement is not only an important scientific endeavor, but will be essential to realizing quantum-enhanced technologies, in particular, quantum-enhanced measurements with precision beyond classical limits. We investigate the heralded generation of multiphoton entanglement for quantum metrology using a reconfigurable integrated waveguide device in which projective measurement of auxiliary photons heralds the generation of path-entangled states. We use four and six-photon inputs, to analyze the heralding process of two- and four-photon NOON states-a superposition of N photons in two paths, capable of enabling phase supersensitive measurements at the Heisenberg limit. Realistic devices will include imperfections; as part of the heralded state preparation, we demonstrate phase superresolution within our chip with a state that is more robust to photon loss.