Chunzhen Li

Fast Recovery of Niobium-based Superconducting Resonators after Laser Illumination

  1. Chunzhen Li,
  2. Yuntao Xu,
  3. Yufeng Wu,
  4. Manuel C. C. Pace,
  5. Matthew D. LaHaye,
  6. Michael Senatore,
  7. and Hong X. Tang
Interfacing superconducting microwave resonators with optical systems enables sensitive photon detectors, quantum transducers, and related quantum technologies. Achieving high optical
pulse repetition is crucial for maximizing the device throughput. However, light-induced deterioration, such as quasiparticle poisoning, pair-breaking-phonon generation, and elevated temperature, hinders the rapid recovery of superconducting circuits, limiting their ability to sustain high optical pulse repetition rates. Understanding these loss mechanisms and enabling fast circuit recovery are therefore critical. In this work, we investigate the impact of optical illumination on niobium nitride and niobium microwave resonators by immersing them in superfluid helium-4 and demonstrate a three-order-of-magnitude faster resonance recovery compared to vacuum. By analyzing transient resonance responses, we provide insights into light-induced dynamics in these superconductors, highlighting the advantages of niobium-based superconductors and superfluid helium for rapid circuit recovery in superconducting quantum systems integrated with optical fields.
arxiv pdf

Shortcuts to Adiabaticity for Open Systems in Circuit Quantum Electrodynamics

  1. Zelong Yin,
  2. Chunzhen Li,
  3. Zhenxing Zhang,
  4. Yicong Zheng,
  5. Xiu Gu,
  6. Maochun Dai,
  7. Jonathan Allcock,
  8. Shengyu Zhang,
  9. and Shuoming An
Shortcuts to adiabaticity (STA) are powerful quantum control methods, allowing quick evolution into target states of otherwise slow adiabatic dynamics. Such methods have widespread
applications in quantum technologies, and various STA protocols have been demonstrated in closed systems. However, realizing STA for open quantum systems has presented a greater challenge, due to complex controls required in existing proposals. Here we present the first experimental demonstration of STA for open quantum systems, using a superconducting circuit QED system consisting of two coupled bosonic oscillators and a transmon qubit. By applying a counterdiabatic driving pulse, we reduce the adiabatic evolution time of a single lossy mode from 800 ns to 100 ns. In addition, we propose and implement an optimal control protocol to achieve fast and qubit-unconditional equilibrium of multiple lossy modes. Our results pave the way for accelerating dynamics of open quantum systems and have potential applications in designing fast open-system protocols of physical and interdisciplinary interest, such as accelerating bioengineering and chemical reaction dynamics.
arxiv pdf