Temperature effects of an asymmetry quantum dot qubit under an applied electric field

Abstract

We study the eigenenergies and eigenfunctions of the ground and first excited states (GFES) of an electron strongly coupled to the LO-phonon in an asymmetry quantum dot (AQD) under an applied electric field by using a variational method of the Pekar type (VMPT). This AQD two-level system may be viewed as a single qubit. When the electron is in the superposition state (SS) of the GFES, the effects of the electric field and temperature on the oscillating period (OP), the time evolution of the electron's probability density (PD) and the coherence time (CT) are obtained. Our numerical results show that the electron's PD and its OP will increase (decrease) with increasing temperature in low (high) temperature regime. The electron's PD will decrease (increase) with increasing electron-phonon (EP) coupling strength in low (high) temperature regime. The OP is an increasing function of the electric field and will decrease obviously (increase tardily) with increasing EP coupling strength when the temperature is in lower (higher) rgime. The CT is an increasing function of the electric field, but a decreasing function of the coupling strength.