Computer simulation of spin states of electrons in nanoscale cavities in the Feynman path integrals representation

Abstract

A method is developed for the ab initio calculation of the distance between the energy levels of different spin states of electrons, as well as the spin of mixed quantum states subjected to thermal fluctuations. It is shown that theoretical investigations in the path integral representation can be carried out not only for mixed states, but also for pure quantum states. The approach proposed by us is free of the one-electron approximation and takes into account all spatial correlations between electrons. Demonstration computer calculations using the Monte Carlo method are carried out for the spin states of electrons in model ellipsoidal quantum dots. The inversion of levels corresponding to high and low spin states is detected in a system of three electrons. The calculations show that it is possible in principle to obtain spin states with arbitrarily close energies by varying the shape of a quantum dot. This fact is of fundamental importance for the prospects of constructing a new generation of storage and computing devices based on the spin qubits.