Quantum Coherent Absorption of Squeezed Light

TL;DR

This paper explores the quantum optical phenomenon of coherent perfect absorption with squeezed light, revealing how it can generate entangled states and serve as a novel tool for quantum state preparation.

Contribution

It introduces the concept of a CPA-gate that transforms squeezed coherent states into entangled squeezed vacuum states without entangling with the absorber.

Findings

Derives quantum absorption coefficients for squeezed states.

Demonstrates complete coherence removal and entanglement generation.

Shows the CPA-gate's potential for quantum state engineering.

Abstract

We investigate coherent perfect absorption (CPA) in quantum optics, in particular when pairs of squeezed coherent states of light are superposed on an absorbing beam splitter. First, by employing quantum optical input-output relations, we derive the absorption coefficients for quantum coherence and for intensity, and reveal how these will differ for squeezed states. Secondly, we present the remarkable properties of a CPA-gate: two identical but otherwise arbitrary incoming squeezed coherent states can be completely stripped off their coherence, producing a pure entangled squeezed vacuum state that with its finite intensity escapes from an otherwise perfect absorber. Importantly, this output state of light is not entangled with the absorbing beam splitter by which it was produced. Its loss-enabled functionality makes the CPA gate an interesting new tool for continuous-variable quantum state preparation.