Model Dynamics for Quantum Computing

TL;DR

This paper introduces a comprehensive master equation model for quantum computing dynamics that accounts for environmental interactions, decoherence, and entropy evolution, aiming to assess stability and gate efficacy in realistic quantum devices.

Contribution

It presents a novel phenomenological master equation incorporating Lindblad and nonlinear Beretta terms for analyzing quantum computing stability under environmental disturbances.

Findings

Model captures decoherence and environmental effects on qubits.

Extension to multi-qubit systems for future generalization.

Insights into thermal equilibrium and entropy in quantum stability.

Abstract

A model master equation suitable for quantum computing dynamics is presented. In an ideal quantum computer (QC), a system of qubits evolves in time unitarily and, by virtue of their entanglement, interfere quantum mechanically to solve otherwise intractable problems. In the real situation, a QC is subject to decoherence and attenuation effects due to interaction with an environment and with possible short-term random disturbances and gate deficiencies. The stability of a QC under such attacks is a key issue for the development of realistic devices. We assume that the influence of the environment can be incorporated by a master equation that includes unitary evolution with gates, supplemented by a Lindblad term. Lindblad operators of various types are explored; namely, steady, pulsed, gate friction, and measurement operators. In the master equation, we use the Lindblad term to describe short time intrusions by random Lindblad pulses. The phenomenological master equation is then extended to include a nonlinear Beretta term that describes the evolution of a closed system with increasing entropy, plus a Bath environment term stipulated by a fixed temperature. Here we explore the case of a simple one-qubit system in preparation for generalization to multi-qubit, qutrit and hybrid qubit-qutrit systems. This model master equation can be used to test the stability of memory and the efficacy of quantum gates. The properties of such hybrid master equations are explored, with emphasis on the role of thermal equilibrium and entropy constraints.