Microwave amplification by using Niobium-based Josephson junction array parametric oscillator

Chun-Yu Liu^1*, Po-Wei Huang¹, Chao-Te Li², Tse-Jun Chen², Io-Chun Hoi³, Yen-Hsiang Lin¹, Ming-Jye Wang², Jeng-Chung Chen¹

¹Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
²Institute of Astronomy and Astrophysics, Academia Sinica, Taipei Da’an, Taiwan
³Department of Physics, City University of Hong Kong, Kowloon, Hong Kong

* Presenter:Chun-Yu Liu, email:a9220312@gmail.com

Quantum parametric oscillators are essential tools for generating and manipulating quantum states, with applications in quantum communication, quantum sensing, and quantum computation. We report the realization of microwave (MW) quantum parametric oscillations within the 4 to 8 GHz range using a Niobium (Nb)-based Josephson-junction array (JJA). The JJA consists of 30 to 400 Josephson junctions (JJs), each coupled with a parallel capacitor to form a transmission line, and is embedded in an external 50-Ohm transmission line, creating an impedance-mismatched resonator. We observe parametric amplification with a gain of up to ~10 dB and a bandwidth of up to 500 MHz, centered within the pump frequency range of 4 to 8 GHz, with saturation near -100 dBm. This amplification is evident in both reflection and transmission signals. Theoretical analysis based on a nonlinear circuit model suggests that the observed behavior arises from parametric oscillations linked to amplification. Our findings demonstrate a novel method for implementing a parametric oscillator with tunable amplification, offering potential applications in quantum sensing, illumination, and qubit readout. Further data and analysis will be presented.

Keywords: quantum computing, quantum illumination, quantum sensing