Quantum speed limit times of qubit systems in time-dependent potentials

Abstract

Quantum speed limits (QSLs) fundamentally bound the evolution times of quantum processes. Most of the Hamiltonians involved in finding QSLs are time-independent; thus, this paper explored the use of time-dependent perturbing potentials. An electron in a two-state system is subjected to a rotating magnetic field, from which, QSLs involving the fastest time when the system is most probably in the state orthogonal from the initial state was obtained. It was shown that when the rotating magnetic field is tuned to resonate with the system's time-independent Hamiltonian, the system gains an orthogonalization time. QSLs obtained from this potential also has the form that are seemingly fundamental in nature. QSLs of the same form could also generate time-energy uncertainty relations.