Eli M. Levenson-Falk

Entanglement assisted probe of the non-Markovian to Markovian transition in open quantum system dynamics

  1. Chandrashekhar Gaikwad,
  2. Daria Kowsari,
  3. Carson Brame,
  4. Xingrui Song,
  5. Haimeng Zhang,
  6. Martina Esposito,
  7. Arpit Ranadive,
  8. Giulio Cappelli,
  9. Nicolas Roch,
  10. Eli M. Levenson-Falk,
  11. and Kater W. Murch
We utilize a superconducting qubit processor to experimentally probe the transition from non-Markovian to Markovian dynamics of an entangled qubit pair. We prepare an entangled state
between two qubits and monitor the evolution of entanglement over time as one of the qubits interacts with a small quantum environment consisting of an auxiliary transmon qubit coupled to its readout cavity. We observe the collapse and revival of the entanglement as a signature of quantum memory effects in the environment. We then engineer the non-Markovianity of the environment by populating its readout cavity with thermal photons to show a transition from non-Markovian to Markovian dynamics, reaching a regime where the quantum Zeno effect creates a decoherence-free subspace that effectively stabilizes the entanglement between the qubits.
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