Landau-Zener dynamics in qubits-oscillator settings

A. B. Tchapda, M. B. Kenmoe, A.D. Kammogne +1 more

Bloch–Zener Oscillations In article number 2300101, Zhongkai Huang and co-workers investigate the transient dynamics of Bloch–Zener oscillations in a 1D qubit chain. By analyzing several tight-binding models, most importantly Wannier–Stark ladder and Landau–Zener models, they find that controlling the band gap is crucial to understanding the interplay between Bloch oscillations and Landau–Zener transitions. This work suggests several routes for future study of these phenomena and provides new insight into the behavior of Bloch–Zener oscillations in complex systems.

A. V. Shytov, Dmitri A. Ivanov, M. V. Feigel’man

Peter Hänggi A, Martijn Wubs, Sigmund Kohler +2 more

A qubit may undergo Landau‐Zener transitions due to its coupling to one or several quantum harmonic oscillators. First we show that for a qubit coupled to one oscillator, Landau‐Zener transitions can be used for single‐photon generation and for the controllable creation of qubit‐oscillator entanglement, with state‐of‐the‐art circuit QED as a promising realization. Second, for a qubit coupled to two cavities, we show that Landau‐Zener sweeps of the qubit are well suited for the robust creation of entangled cavity states, in particular symmetric Bell states, with the qubit acting as the entanglement mediator. Finally, for a qubit coupled to an environment or bath we propose to employ dissipative Landau‐Zener sweeps of the qubit for the detection of bath properties. At the heart of our proposals lies the calculation of the exact Landau‐Zener transition probability for the qubit, by summing all orders of the corresponding series in time‐dependent perturbation theory.

Guozhu Sun, Xueda Wen, Ming Gong +6 more

Landau-Zener transition (LZT) has been explored in a variety of physical systems for coherent population transfer between different quantum states. In recent years, there have been various proposals for applying LZT to quantum information processing because when compared to the methods using ac pulse for coherent population transfer, protocols based on LZT are less sensitive to timing errors. However, the effect of finite range of qubit energy available to LZT based state control operations has not been thoroughly examined. In this work, we show that using the well-known Landau-Zener formula in the vicinity of an avoided energy-level crossing will cause considerable errors due to coherent oscillation of the transition probability in a single-passage LZT experiment. The data agree well with the numerical simulations which take the transient dynamics of LZT into account. These results not only provide a closer view on the issue of finite-time LZT but also shed light on its effects on the quantum state manipulation.

Maxim Vavilov, Canran Xu, Amrit Poudel