量子论坛二十七讲

报告题目：Autler-Townes splitting and motional averaging in superconducting quantum circuits

报告人：李剑国防科技大学理学院物理系和量子信息学科交叉中心副研究员，芬兰Aalto University博士

报告时间：2017年4月21日上午10:00

报告地点：量子楼410报告厅

报告摘要：

I will present my experimental and theoretical work on superconducting quantum circuits carried out at the Low Temperature Laboratory, Aalto University.

The first part of this presentation will focus on the Autler-Townes splitting observed in a superconducting phase qubit, both in steady-state and in time domain. The experimental observations can be qualitatively described by a simple model restricted to three lowest energy levels of the phase qubit. A full solution of the master equation including higher levels provides excellent agreement with the experimental data.

Simulating motional averaging effect with a transmon qubit will be addressed in the second part of the presentation. To mimic this effect, the energy splitting of the transmon jumps stochastically between two discrete values, due to the pseudo-random telegraph noise introduced to the flux bias of it. When the jumping is faster than a dynamical threshold set by the energy splitting displacement, the initially separated spectral lines merge into a single motional-averaged line. With sinusoidal modulation of the flux bias, we observe a complex pattern of additional sidebands and a photon-assisted Landau-Zener-Stückelberg interference pattern.

报告人简历：

李剑，2004年在中南大学获得学士学位，2006年在瑞典Chalmers University of Technology获得硕士学位，2012年在芬兰Aalto University获得博士学位。2012年—2016年分别在芬兰Aalto University和英国University of Glasgow从事博士后研究工作。2016年5月至今，任职国防科技大学理学院物理系和量子信息学科交叉中心副研究员。报告人近年来主要从事基于超导量子器件的量子信息处理，石墨烯微波光机(optomechanics)系统及SOI光波导集成近红外波段超导纳米线单光子探测器(SNSPD)等方面的研究工作，已在Nature Communications, Phys. Rev. B, Nature和Phys. Rev. Lett.等国际权威刊物上发表论文多篇。