Microwave amplification via interfering multi-photon processes in a half-waveguide quantum electrodynamics system

• DOI: 10.48550/arxiv.2302.07442
• Publication Date: 2023-01-01
• Authors: Aziz, Fahad; Lin, Kuan Ting; Wen, Ping Yi; Samina; Lin, Yu Chen; Wiegand, Emely; Lee, Ching-Ping; Cheng, Yu-Ting; Chen, Ching-Yeh; Chien, Chin-Hsun; Hsieh, Kai-Min; Huang, Yu-Huan; Hou, Ian; Chen, Jeng-Chung; Lin, Yen-Hsiang; Kockum, Anton Frisk; Lin, Guin Dar; Hoi, Io-Chun
• Keywords: Quantum Physics; 0103 physical sciences; FOS: Physical sciences; Quantum Physics (quant-ph); 01 natural sciences; 7. Clean energy

We investigate the amplification of a microwave probe signal by a superconducting artificial atom, a transmon, strongly coupled to the end of a one-dimensional semi-infinite transmission line. The end of the transmission line acts as a mirror for microwave fields. Due to the weak anharmonicity of the artificial atom, a strong pump field creates multi-photon excitations among the dressed states. Transitions between these dressed states, Rabi sidebands, give rise to either amplification or attenuation of the weak probe. We obtain a maximum amplitude amplification of about 18 %, higher than in any previous experiment with a single artificial atom, due to constructive interference between Rabi sidebands. We also characterize the noise properties of the system by measuring the spectrum of spontaneous emission.