Gaussian entropy and decoherence of qubit in hydrogenic impurity-center semiconductor quantum dot by confined spherical Gaussian potential

In this paper, we analyze the rationality and superiority of constructing the qubit using the donor-center quantum dots with the spherical Gaussian (SG) confinement potential. The energies of the ground state and the first excited state of the system were derived based on the Pekar-type variational method. A superposition state or a qubit is constructed using these results, and the Gaussian entropy of the system is derived. The spontaneous emission rate of LO phonons is discussed based on the Fermi Golden rule. The influence of the LO phonon spontaneous emission rate and Gaussian entropy on the decoherence of the donor-center quantum dot qubit is investigated, respectively. The radius R-0 of a quantum dot corresponding to the state where the system information loss reaches the maximum due to decoherence is observed; It is found that the Gaussian entropy changes from increasing to decreasing with the increase of the well depth in the 3.5r(p) < R < 6.0r(p) interval; The decoherence time decreases with increasing the well depth, but increases with increasing the electron-phonon coupling constant, the dielectric constant ratio, and the dispersion coefficient, respectively. The Gaussian entropy periodically oscillates with time, and the oscillation amplitude increases with increasing the electron-phonon coupling constant and the dielectric constant ratio. The period of oscillation decreases with increasing the electron-phonon coupling strength and the dielectric constant ratio. When the electron-phonon coupling constant is equal to 6.0, we observe the collapse and revival of the entropy, that is, the oscillation behavior of entropy under the standing wave envelope, and entropy evolves into a wave envelope. Our work proves that qubit decoherence can be suppressed by doping or modulating the electron-phonon coupling constants and dispersion coefficients of materials.