Observation of coherent oscillation in single-passage Landau-Zener transitions.

Guozhu Sun,Ming Gong,Shi-Liang Zhu,Yang Yu,Xueda Wen,Peiheng Wu,Dan-Wei Zhang,Jian Chen,Siyuan Han

doi:10.1038/srep08463

Abstract

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.

Highlights

Landau-Zener transition (LZT) has been explored in a variety of physical systems for coherent population transfer between different quantum states
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
As discussed below in more detail, when the transition frequency of the qubit v10 is close to that of the TLS vTLS, which is fixed, the first and second excited states of the coupled qubit-TLS system form an effective quantum two-level system described by the LZ Hamiltonian (1)

Summary

Introduction

Landau-Zener transition (LZT) has been explored in a variety of physical systems for coherent population transfer between different quantum states. 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 provide a closer view on the issue of finite-time LZT and shed light on its effects on the quantum state manipulation. 1suqchffieffiðffisffitffiyffiÞffisffi2ffitffizeffiffimffiffiDffiffisffiffi2,ffi 2 when e(t) is swept can occur and the through the avoided crossing, transition probability is given by the well-known Landau-Zener (LZ) formula

Methods

Results

Conclusion