Effect of Noise on the Decoherence of a Central Electron Spin Coupled to an Antiferromagnetic Spin Bath

G C Fouokeng,Massou Siaka,M Tchoffo,Lukong Cornelius Fai,S Moussiliou,J C Ngana Kuetche

doi:10.1155/2014/526205

Abstract

We analyze the influence of a two-state autocorrelated noise on the decoherence and on the tunneling Landau-Zener (LZ) transitions during a two-level crossing of a central electron spin (CES) coupled to a one dimensional anisotropic-antiferomagnetic spin, driven by a time-dependent global external magnetic field. The energy splitting of the coupled spin system is found through an approach that computes the noise-averaged frequency. At low magnetic field intensity, the decoherence (or entangled state) of a coupled spin system is dominated by the noise intensity. The effects of the magnetic field pulse and the spin gap antiferromagnetic material used suggest to us that they may be used as tools for the direct observation of the tunneling splitting through the LZ transitions in the sudden limit. We found that the dynamical frequencies display basin-like behavior decay with time, with the birth of entanglement, while the LZ transition probability shows Gaussian shape.

Highlights

The physics of decoherence including LZ transition in a superconducting quantum spin devices is a subject of fundamental importance and of great current interest, for example, in the context of prospective “coupling-central electron spin (CES) devices” [1, 2]
This work was extended in our recent paper [2] in which we showed that the two different magnon modes, resulting from the frequency splitting via the application of the variable B-field (VBF), exhibit each a resonance peak of similar amplitude at different time ranges
We have investigated theoretically decoherence and the LZ transition of a superconducting-qubit coupled spin system, where the system exhibit bistability mediated by the CES trapped by the vibronic coupling

Summary

Introduction

The physics of decoherence including LZ transition in a superconducting quantum spin devices is a subject of fundamental importance and of great current interest, for example, in the context of prospective “coupling-CES devices” [1, 2]. It is possible to manipulate the values of the environment or system parameters at any time such that the qubits undergo one-qubit or two-qubit gate operations [11,12,13] It is found in the review of many previous works that the decoherence of electron spins coupled to a baths of nuclear spins in quantum dots [14,15,16] or solid-state impurity centers [17, 18] is a key issue in spin-based quantum information processing because of the long coherence time of the quantum spin systems [19,20,21,22,23].

Model Hamiltonian

Landau-Zener Tunneling Transition Probability

Conclusion