Coherence analysis of phase-controlled HOM effects

TL;DR

This paper employs a coherence-based approach to analyze phase-controlled Hong-Ou-Mandel effects, revealing their nature as a coherent phenomenon between entangled photons, challenging traditional particle-based interpretations.

Contribution

It introduces a pure coherence framework to analyze phase-controlled HOM effects, providing a new perspective on their underlying quantum phenomena.

Findings

HOM effects can be understood as a coherent phenomenon between entangled photons.

The phase control in HOM effects is a collective property, not an individual photon attribute.

The coherence approach offers a general solution to phase-controlled HOM effects.

Abstract

The second-order intensity correlation of entangled photons has been intensively studied for decades, particularly for the Hong-Ou-Mandel (HOM) effect and nonlocal correlation -- key quantum phenomena that have no classical counterparts. Recently, a path-entangled two-photon state has been experimentally demonstrated for both bosonic (symmetric) and fermionic (anti-symmetric) HOM effects by manipulating the photon phase at one input port. Entanglement represents a quantum superposition of path- or energy-correlated two-photon states with a relative phase. According to the conventional quantum mechanics, this phase is not an individual property but collective attribute of interacting photons. Here, the wave nature of photons is employed to coherently analyze the phase-controlled HOM effects recently observed in npj Quantum Info. 5, 43 (2019). A pure coherence approach is applied to derive a general solution for these phase-controlled HOM effects. Consequently, the quantum mystery of HOM effects, traditionally interpreted through the particle nature of quantum mechanics, is revealed as a coherent phenomenon between entangled photons via a selective choice of correlated photons.