Entropy evolution law in a laser process

TL;DR

This paper derives the entropy variation law in a laser process using the entangled state representation, revealing how gain and damping influence entropy evolution and providing a photon number evolution formula.

Contribution

It introduces a novel method to derive the entropy variation law in laser processes via Kraus operators and entangled state representation.

Findings

Entropy behavior is governed by gain and damping competition.

Photon number evolution formula is obtained.

First derivation of entropy variation law in laser processes.

Abstract

For the first time, we obtain the entropy variation law in a laser process after finding the Kraus operator of the master equation describing the laser process with the use of the entangled state representation. The behavior of entropy is determined by the competition of the gain and damping in the laser process. The photon number evolution formula is also obtained.