Conditional cooling limit for a quantum channel going through an incoherent environment

TL;DR

This paper establishes and experimentally verifies a fundamental conditional cooling limit for quantum channels passing through incoherent environments, crucial for maintaining entanglement in quantum technologies.

Contribution

It introduces a new conditional cooling limit for quantum channels in incoherent environments and experimentally demonstrates its validity.

Findings

The cooling limit determines when a quantum channel preserves entanglement.

Experimental verification confirms the theoretical predictions.

The limit is essential for entanglement-based quantum applications.

Abstract

We propose and experimentally verify a cooling limit for a quantum channel going through an incoherent environment. The environment consists of a large number of independent non-interacting and non-interfering elementary quantum systems - qubits. The qubits travelling through the channel can only be randomly replaced by environmental qubits. We investigate a conditional cooling limit that exploits an additional probing output. The limit specifies when the single-qubit channel is quantum, i.e. it preserves entanglement. It is a fundamental condition for entanglement-based quantum technology.