Decoherence of Magneto-Bipolaron with Strong Coupling in a Quantum Dot Qubit Under Applied Electric Field

In this paper, we study the physical properties and decoherence of strong coupling magneto-bipolaron qubit in a quantum dot under the effect of an external electric field. The magneto-bipolaron energies of ground and first excited states are evaluated using the Pekar variational method. The decoherence time and entropy are also evaluated. All these calculations are intended to show firstly the effect of both the magnetic and the electric fields on the quasi-particles’ properties in the quantum dot. Our results show that all studied quasi-particles properties in the quantum dot are closely influenced by magnetic and electric fields. The decoherence time increases with increasing of the electric field strength, and decreases with increasing of the magnetic field strength and the electron–phonon coupling constant. From our analysis, it is obvious to see that the application of electric field and magnetic field have opposite effects on the qubit. Comparing both fields, the electric field is advantageous for qubit survival and information storage, while the magnetic field is detrimental to qubit survival and information storage, respectively. The entropy increases with increasing of the electric field strength, and decreases with increasing of the magnetic field strength. We also observe that in the absence of magnetic and electric fields, the entropy varies very slightly with the increase of the confinement strength. We can deduce that, these external fields can help us to modulate the period of information transfer in the system, and hence can be used to control its coherence.