Path-phase duality of an interfering particle with translational-internal entanglement

TL;DR

This paper explores how translational-internal entanglement in particles affects the complementarity principle in interferometry, enabling enhanced phase detection and path distinguishability beyond standard quantum limits.

Contribution

It introduces the concept of phase-dependent path distinguishability using TIE states, challenging traditional complementarity constraints in quantum interferometry.

Findings

TIE states allow phase-dependent path distinguishability.

Enhanced detection of small phase shifts is possible.

Standard complementarity constraints can be surpassed with TIE states.

Abstract

The aim of this paper is to revisit the implications of complementarity when we inject into a Mach Zehnder interferometer particles with internal structure, prepared in special translational-internal entangled (TIE) states. This correlation causes the path distinguishability to be phase dependent in contrast to the standard case. We show that such a TIE state permits us to detect small phase shifts along with almost perfect path distinguishability, beyond the constraints imposed by complementarity on simultaneous which-way and which-phase measurements for standard cases (when distinguishability is independent of interferometric phase).