报告题目：On chip quantum optics with superconducting artificial atoms in one dimensional space

报告人：许耀铨，香港城市大学

邀请人：游建强

时间：2023年8月25日（周五）上午10:00

地点：紫金港校区海纳苑8幢322教室

摘要：In this talk, I will address recent advances in quantum optics with superconducting artificial atoms in one dimensional (1D) space. In the first sets of experiments, we embed a transmon in a transmission line. When driving the qubit strongly on resonance such that a Mollow triplet appears, we observe a few percent amplitude gain for a weak probe at frequencies in-between the triplet. This amplification is not due to population inversion, but instead results from a four-photon process that converts energy from the strong drive to the weak probe [1]. In the second sets of experiment, we embed a transmon at a distance from the end (mirror) of a transmission line. By tuning the wavelength of the atom, we effectively change the normalized distance between atom and mirror, allowing us to effectively move the atom from a node to an antinode of the vacuum fluctuations. We probe the strength of vacuum fluctuations by measuring spontaneous emission rate of the atom [2]. In the third sets of experiment, we place two superconducting qubits in a transmission line terminated by a mirror, which suppresses decay. We measure a collective Lamb shift reaching 0.8% of the qubit transition frequency and exceeding the transition linewidth [3]. In the fourth sets of experiment, we demonstrate that coherent-state microwave photons, with an optimal temporal waveform, can be efficiently loaded onto a single superconducting artificial atom in a semi-infinite 1D transmission-line waveguide. Using a weak coherent state (average photon number N<<1) with an exponentially rising waveform, whose time constant matches the decoherence time of the artificial atom, we demonstrate a loading efficiency of above 94% from 1D semi-free space to the artificial atom [4].

References

[1] P. Y. Wen et al. Physical Review Letters 120, 063603 (2018)

[2] I.-C. Hoi et al. Nature Physics 11, 1045 (2015)

[3] P. Y. Wen et al. Physical Review Letters 123, 233602 (2019)  

[4] W. J. Lin et al. Nano Letters, 22, 20, 8137 (2022)

个人简介：Prof. Io-Chun Hoi (许耀铨), Associate Professor, City University of Hong Kong, Hong Kong SAR, China

Prof. Io-Chun Hoi received B.S. and Ph.D. in Electro-Physics Department, National Chiao Tung University, Taiwan and Department of Microtechnology and Nanoscience, Chalmers University of Technology, Sweden, respectively. He did his postdoctoral research at University of California, Santa Barbara, U.S.A. He was an assistant professor and associate professor at National Tsing Hua University, Taiwan. He is the author or co-author of >20 publications, including 1 first-authored Nature Physics, 3 first-authored Physical Review Letters, 2 corresponding-authored Physical Review Letters and 1 corresponding-authored Nano Letters.

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