The Coherence Time of Strong-Coupling Bound Polaron in an Asymmetrical Gaussian Potential Quantum Well Qubit

Based on the Pekar-type variational approach, we systematically investigate the dynamical evolution of electron quantum states under strong electron-LO-phonon coupling in an asymmetric Gaussian potential quantum well (QW) subject to an applied electric field. The eigenenergies and wave functions of the ground and first excited states are accurately determined, confirming that this Gaussian potential QW system can serve as a stable two-level qubit. We focus on the spatiotemporal evolution of the electron in a superposition state, revealing that the electron probability density exhibits periodic oscillations within the quantum well. Notably, due to the asymmetric Gaussian potential along the growth direction, the electron probability density displays a distinct double-peak structure, in sharp contrast to the single-peak distribution observed in conventional two-dimensional symmetric potential wells. The oscillation period shows significant parameter dependence: it increases monotonically with the applied electric field strength but decreases with both the potential well height and the polaron radius. Particularly noteworthy is the non-monotonic dependence of the oscillation period on the confinement potential range—the period decreases as the range increases below a critical value, increases above it, and reaches a minimum at the critical point. The above research results can provide important theoretical support for the regulation of the photoelectric properties of low-dimensional materials and the development of their applications.