Magnetic Field Effect on the Coherence Time of Asymmetric Gaussian Confinement Potential Quantum Well Qubits

Abstract

Under a strong electron-LO-phonon coupling in asymmetric Gaussian confinement potential quantum wells (AGCPQWs) when exposed to external magnetic fields, the AGCPQW qubit coherent time can be obtained from Fermi's golden rule and the variational method of Pekar type. We have calculated the coherence times of two-level quantum systems in RbCl AGCPQWs in external magnetic fields with varying with cyclotron frequency of magnetic field, confinement potential range (CPR), AGCPQW height, oscillating frequency and polaron radius were theoretically calculated. Based on the numerical results, we found that the coherence time was increased by decreasing magnetic field cyclotron frequency, AGCPQW height, oscillating frequency and polaron radius. Also, the coherence time was decreased with CPR for $R < 0.7{\text{nm}}$ and increased for $R > 0.7{\text{nm}}$, with minimum value at $R = 0.7{\text{nm}}$, $\omega_{c} = 10 \times 10^{13} {\text{Hz}}$ and $\tau = 409.9{\text{ps}}$.