Quantum reversal: a general theory of coherent quantum absorbers

TL;DR

This paper introduces a general theory of coherent quantum absorbers, called quantum reversal, which uses Petz recovery maps to reverse effects between quantum systems while maintaining entanglement.

Contribution

It generalizes the concept of coherent quantum absorbers by formulating reversal conditions with Petz recovery maps, streamlining previous approaches.

Findings

Reversal conditions are expressed through Petz recovery maps and Kraus operators.

The theory unifies and extends existing models of coherent quantum absorbers.

Provides a rigorous mathematical framework for quantum reversal processes.

Abstract

The fascinating concept of coherent quantum absorber - which can absorb any photon emitted by another system while maintaining entanglement with that system - has found diverse implications in open quantum system theory and quantum metrology. This work generalizes the concept by proposing the so-called reversal conditions for the two systems, in which a "reverser" coherently reverses any effect of the other system on a field. The reversal conditions are rigorously boiled down to concise formulas involving the Petz recovery map and Kraus operators, thereby generalizing as well as streamlining the existing treatments of coherent absorbers.