Jaewoo Lee

Characterizing losses in InAs two-dimensional electron gas-based gatemon qubits

  1. William M. Strickland,
  2. Jaewoo Lee,
  3. Lukas Baker,
  4. Krishna Dindial,
  5. Bassel Heiba Elfeky,
  6. Mehdi Hatefipour,
  7. Peng Yu,
  8. Ido Levy,
  9. Vladimir E. Manucharyan,
  10. and Javad Shabani
The tunnelling of cooper pairs across a Josephson junction (JJ) allow for the nonlinear inductance necessary to construct superconducting qubits, amplifiers, and various other quantum
circuits. An alternative approach using hybrid superconductor-semiconductor JJs can enable a superconducting qubit architecture with full electric field control. Here we present continuous-wave and time-domain characterization of gatemon qubits based on an InAs 2DEG. We show that the qubit undergoes a vacuum Rabi splitting with a readout cavity and we drive coherent Rabi oscillations between the qubit ground and first excited states. We measure qubit coherence times to be T1= 100 ns over a 1.5 GHz tunable band. While various loss mechanisms are present in III-V gatemon circuits we detail future directions in enhancing the coherence times of qubit devices on this platform.
arxiv pdf

Quasiparticle dynamics in epitaxial Al-InAs planar Josephson junctions

  1. Bassel Heiba Elfeky,
  2. William M. Strickland,
  3. Jaewoo Lee,
  4. James T. Farmer,
  5. Sadman Shanto,
  6. Azarin Zarassi,
  7. Dylan Langone,
  8. Maxim G. Vavilov,
  9. Eli M. Levenson-Falk,
  10. and Javad Shabani
Quasiparticle (QP) effects play a significant role in the coherence and fidelity of superconducting quantum circuits. The Andreev bound states of high transparency Josephson junctions
can act as low-energy traps for QPs, providing a mechanism for studying the dynamics and properties of both the QPs and the junction. We study the trapping and clearing of QPs from the Andreev bound states of epitaxial Al-InAs Josephson junctions incorporated in a superconducting quantum interference device (SQUID) galvanically shorting a superconducting resonator to ground. We use a neighboring voltage-biased Josephson junction to inject QPs into the circuit. Upon the injection of QPs, we show that we can trap and clear QPs when the SQUID is flux-biased. We examine effects of the microwave loss associated with bulk QP transport in the resonator, QP-related dissipation in the junction, and QP poisoning events. By monitoring the QP trapping and clearing in time, we study the dynamics of these processes and find a time-scale of few microseconds that is consistent with electron-phonon relaxation in our system and correlated QP trapping and clearing mechanisms. Our results highlight the QP trapping and clearing dynamics as well as the associated time-scales in high transparency Josephson junctions based fabricated on Al-InAs heterostructures.
arxiv pdf