Quantum switch instabilities with an open control

TL;DR

This paper investigates how environmental interactions cause instabilities in quantum switches with open control systems, affecting interference, measurement, and thermodynamic protocols in quantum causal order superpositions.

Contribution

It introduces a collisional model to analyze environmental effects on quantum causal switches and explores temperature-dependent instabilities impacting protocol performance.

Findings

Environmental instabilities affect interference in quantum switches.

Temperature influences control post-selection outcomes.

Protocols like measurement switching and quantum refrigeration are impacted.

Abstract

The superposition of causal order shows promise in various quantum technologies. However, the fragility of quantum systems arising from environmental interactions, leading to dissipative behavior and irreversibility, demands a deeper understanding of the possible instabilities in the coherent control of causal orders. In this work, we employ a collisional model to investigate the impact of an open control system on the generation of interference between two causal orders. We present the environmental instabilities for the switch of two arbitrary quantum operations and examine the influence of environmental temperature on each potential outcome of control post-selection. Additionally, we explore how environmental instabilities affect protocol performance, including switching between mutually unbiased measurement observables and refrigeration powered by causal order superposition, providing insights into broader implications.