Quasiprobability distributions in open quantum systems: spin-qubit systems

TL;DR

This paper explores quasiprobability distributions in open spin-qubit systems, deriving analytic expressions for various states and analyzing nonclassical features and quantum-classical transition effects.

Contribution

It provides new analytic formulas for quasiprobability distributions in open spin systems, including multi-qubit and higher spin states, enhancing understanding of nonclassicality.

Findings

Nonclassical characteristics are present in all studied systems.

Analytic expressions for W, P, Q, and F functions are derived.

Quantum to classical transition is clarified through nonclassical volume analysis.

Abstract

Quasiprobability distributions (QDs) in open quantum systems are investigated for $SU(2)$, spin like systems, having relevance to quantum optics and information. In this work, effect of both quantum non-demolition (QND) and dissipative open quantum systems, on the evolution of a number of spin QDs are investigated. Specifically, compact analytic expressions for the $W$, $P$, $Q$, and $F$ functions are obtained for some interesting single, two and three qubit states, undergoing general open system evolutions. Further, corresponding QDs are reported for an N qubit Dicke model and a spin-1 system. The existence of nonclassical characteristics are observed in all the systems investigated here. The study leads to a clear understanding of quantum to classical transition in a host of realistic physical scenarios. Variation of the amount of nonclassicality observed in the quantum systems, studied here,are also investigated using nonclassical volume.