📝 SummarXiv

Abstract

Photon distinguishability is a key factor limiting quantum interference in photonic devices, directly impacting the performance of protocols such as Boson Sampling and photonic quantum computing. We present a basis-independent framework for analyzing multi-photon interference, identifying a necessary and sufficient condition under which distinguishability behaves as a stochastic error process. This condition enables any multi-photon state to be uniquely expressed as a classical mixture of partition states -- discrete configurations representing different patterns of photon distinguishability. We introduce an experimentally implementable operation, analogous to Pauli twirling, that enforces this condition without compromising computational hardness. The resulting probability distribution over partition states defines the system's incoherent distinguishability spectrum, which we show can be fully characterized through a specific set of experiments. Building on this structure, we also demonstrate the existence of an error mitigation strategy. This framework clarifies key challenges in defining genuine multi-photon indistinguishability, links previous perspectives on partial distinguishability, and provides a rigorous foundation for robust photonic protocols.