Instituto de Ciencia de Materiales de Madrid
     Condensed Matter Theory    
   Sigmund Kohler home | cv | research | publications  

Landau-Zener transitions in qubits controlled by electromagnetic fields

Martijn Wubs, Keiji Saito, Sigmund Kohler, Yosuke Kayanuma, and Peter Hänggi
New J. Phys. 7, 218 (2005)

We investigate the influence of a dipole interaction with a classical radiation field on a qubit during a continuous change of a control parameter. In particular, we explore the non-adiabatic transitions that occur when the qubit is swept with linear speed through resonances with the time-dependent interaction. Two classic problems come together in this model: the Landau-Zener (LZ) and the Rabi problem. The probability of LZ transitions now depends sensitively on the amplitude, the frequency and the phase of the Rabi interaction. The influence of the static phase turns out to be particularly strong, since this parameter controls the time-reversal symmetry of the Hamiltonian. In the limits of large and small frequencies, analytical results obtained within a rotating-wave approximation compare favourably with a numerically exact solution. We discuss physical realizations in microwave optics, quantum dots and molecular nanomagnets.

[ICMM-CSIC] [Condensed Matter Theory]
last modified: 15.3.2024 by Sigmund Kohler