Quantum wire and magnetic control of a spin qubit in the Landau-Zener-Stuckelberg interferometry transition

Landau-Zener-Stu ckelberg interferometry is extensively investigated in a 3D heterostructure magnetic quantum wire. Local magnetic fields are used to coherently manipulate and control a qubit's quantum state. For our numerical calculations, a parabolic confinement is assumed. Energy eigenvalues, non-adiabatic and adiabatic transition probabilities are calculated from the diabatic and adiabatic bases for two-level systems. Here, we show that the spatial crossing between interspin levels becomes a spatial anticrossing if the two spin states are coupled by external fields, and that consequently, due to the spin dependence of the harmonic confinement, it will undergo Landau-Zener-Stuckelberg interference. It is shown that the system undergoes nonadiabatic Landau-Zener dynamics for a strong confinement in a strong external field, whereas a weak external field induces adiabatic Landau-Zener transition dynamics. Our system allows the coupling strength between the level states at the anti(crossing) point to be modulated. This system allows one to tune the wire's parabolic confinement potential using experimentally accessible parameters.