Geometry-Controlled Freezing and Revival of Bell Nonlocality through Environmental Memory

TL;DR

This paper demonstrates how geometric control of qubit placement in structured reservoirs can store, revive, or suppress Bell nonlocality through environmental memory effects, with practical implications for quantum technologies.

Contribution

It introduces a geometric control mechanism for Bell nonlocality via structured reservoirs, deriving criteria for nonlocality emergence and proposing a Bell-based measure for backflow effects.

Findings

Bell nonlocality can be revived without entangling drives.

Discrete recurrence times enable Bell violation from product states.

Subwavelength displacements affect nonlocality lifetime quadratically.

Abstract

We show that the distance between two qubits coupled to a structured reservoir acts as a single geometric control that can store, revive, or suppress Bell nonlocality. In a mirror-terminated guide, quantum correlations lost to the bath return at discrete recurrence times, turning a product state into a Bell-violating one without any entangling drive (only local basis rotations/readout). In the continuum limit, we derive closed-form criteria for the emergence of nonlocality from backflow, and introduce a Bell-based analogue of the BLP measure to quantify this effect. We also show how subwavelength displacements away from a decoherence-free node quadratically reduce the lifetime of a dark state or bright state, enabling highly sensitive interferometric detection. All results rely on analytically solvable models and are compatible with current superconducting and nanophotonic platforms, offering a practical route to passive, geometry-controlled non-Markovian devices.