W. Y. Liu

A flux tunable superconducting quantum circuit based on Weyl semimetal MoTe2

  1. K. L. Chiu,
  2. D. G. Qian,
  3. J. W. Qiu,
  4. W. Y. Liu,
  5. D. Tan,
  6. V. Mosallanejad,
  7. S. Liu,
  8. Z. T. Zhang,
  9. Y. Zhao,
  10. and D. P. Yu
Weyl semimetals for their exotic topological properties have drawn considerable attention in many research fields. When in combination with s-wave superconductors, the supercurrent
can be carried by their topological surface channels, forming junctions mimic the behavior of Majorana bound states. Here, we present a transmon-like superconducting quantum intereference device (SQUID) consists of lateral junctions made of Weyl semimetal Td-MoTe2 and superconducting leads niobium nitride (NbN). The SQUID is coupled to a readout cavity made of molybdenum rhenium (MoRe), whose response at high power reveal the existence of the constituting Josephson junctions (JJs). The loop geometry of the circuit allows the resonant frequency of the readout cavity to be tuned by the magnetic flux. We demonstrate a JJ made of MoTe2 and a flux-tunable transmon-like circuit based on Weyl materials. Our study provides a platform to utilize topological materials in SQUID-based quantum circuits for potential applications in quantum information processing.
arxiv pdf

Coherent population transfer between weakly-coupled states in a ladder-type superconducting qutrit

  1. H. K. Xu,
  2. W. Y. Liu,
  3. G. M. Xue,
  4. F. F. Su,
  5. H. Deng,
  6. Ye Tian,
  7. D. N. Zheng,
  8. Siyuan Han,
  9. Y. P. Zhong,
  10. H. Wang,
  11. Yu-Xi Liu,
  12. and S. P. Zhao
Stimulated Raman adiabatic passage (STIRAP) offers significant advantages for coherent population transfer between un- or weakly-coupled states and has the potential of realizing efficient
quantum gate, qubit entanglement, and quantum information transfer. Here we report on the realization of STIRAP in a superconducting phase qutrit – a ladder-type system in which the ground state population is coherently transferred to the second-excited state via the dark state subspace. The result agrees well with the numerical simulation of the master equation, which further demonstrates that with the state-of-the-art superconducting qutrits the transfer efficiency readily exceeds 99% while keeping the population in the first-excited state below 1%. We show that population transfer via STIRAP is significantly more robust against variations of the experimental parameters compared to that via the conventional resonant π pulse method. Our work opens up a new venue for exploring STIRAP for quantum information processing using the superconducting artificial atoms.
arxiv pdf