Eur. Phys. J. D (2015) 69: 246
https://doi.org/10.1140/epjd/e2015-60359-1

Regular Article

Geometric phase in inhomogeneous optical nutation

¹ School of Physics and Technology, Wuhan University, Wuhan 430072, P.R. China
² Institute of Applied Physics and Materials Engineering, Faculty of Science and Technology, University of Macau, Macao, P.R. China
³ College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022, P.R. China

^a e-mail: guolp@whu.edu.cn

Received: 18 June 2015
Received in final form: 7 August 2015
Published online: 5 November 2015

Abstract

Optical nutation and its geometric phase are investigated in terms of an inhomogeneous Bloch equation with a constant term. The analytic solution of optical nutation is obtained by mapping it onto a Bloch sphere structure. We find that a constant, from the equilibrium value of the population inversion in the absence of the laser beam, trends to keep the quantum coherence and is helpful to preserve quantum message. We show that the Berry phase of optical nutation is related to the inner evolution in processing of the optical nutation under a quasicyclic evolution. Furthermore, we find that the Berry phases of two-state mixture change very slowly with its environment variable so as to be robust against the decoherent effect. Our results provide a guidance to implement fault-tolerant geometric quantum computation in the echo approach with an inhomogeneous Bloch equation.