Quantum-enhanced interferometry with large heralded photon-number states

TL;DR

This paper demonstrates quantum-enhanced optical interferometry using large heralded photon-number states up to 8 photons, showing potential for improved phase sensitivity even with optical losses, advancing quantum metrology.

Contribution

It introduces a method to generate and utilize large heralded photon-number states for interferometry, surpassing previous photon-number limits and demonstrating robustness against optical loss.

Findings

Achieved interferometry with up to 8 heralded photons.

Demonstrated quantum-enhanced phase sensitivity with large photon states.

Showed potential for practical quantum metrology despite optical losses.

Abstract

Quantum phenomena such as entanglement can improve fundamental limits on the sensitivity of a measurement probe. In optical interferometry, a probe consisting of $N$ entangled photons provides up to a $\sqrt{N}$ enhancement in phase sensitivity compared to a classical probe of the same energy. Here, we employ high-gain parametric down-conversion sources and photon-number-resolving detectors to perform interferometry with heralded quantum probes of sizes up to $N=8$ (i.e. measuring up to 16-photon coincidences). Our probes are created by injecting heralded photon-number states into an interferometer, and in principle provide quantum-enhanced phase sensitivity even in the presence of significant optical loss. Our work paves the way towards quantum-enhanced interferometry using large entangled photonic states.