Jash Banker

Quantum electrodynamics in a topological waveguide

  1. Eunjong Kim,
  2. Xueyue Zhang,
  3. Vinicius S. Ferreira,
  4. Jash Banker,
  5. Joseph K. Iverson,
  6. Alp Sipahigil,
  7. Miguel Bello,
  8. Alejandro Gonzalez-Tudela,
  9. Mohammad Mirhosseini,
  10. and Oskar Painter
While designing the energy-momentum relation of photons is key to many linear, non-linear, and quantum optical phenomena, a new set of light-matter properties may be realized by employing
the topology of the photonic bath itself. In this work we investigate the properties of superconducting qubits coupled to a metamaterial waveguide based on a photonic analog of the Su-Schrieffer-Heeger model. We explore topologically-induced properties of qubits coupled to such a waveguide, ranging from the formation of directional qubit-photon bound states to topology-dependent cooperative radiation effects. Addition of qubits to this waveguide system also enables direct quantum control over topological edge states that form in finite waveguide systems, useful for instance in constructing a topologically protected quantum communication channel. More broadly, our work demonstrates the opportunity that topological waveguide-QED systems offer in the synthesis and study of many-body states with exotic long-range quantum correlations.
arxiv pdf

Collapse and Revival of an Artificial Atom Coupled to a Structured Photonic Reservoir

  1. Vinicius S. Ferreira,
  2. Jash Banker,
  3. Alp Sipahigil,
  4. Matthew H. Matheny,
  5. Andrew J. Keller,
  6. Eunjong Kim,
  7. Mohammad Mirhosseini,
  8. and Oskar Painter
A structured electromagnetic reservoir can result in novel dynamics of quantum emitters. In particular, the reservoir can be tailored to have a memory of past interactions with emitters,
in contrast to memory-less Markovian dynamics of typical open systems. In this Article, we investigate the non-Markovian dynamics of a superconducting qubit strongly coupled to a superconducting slow-light waveguide reservoir. Tuning the qubit into the spectral vicinity of the passband of this waveguide, we find non-exponential energy relaxation as well as substantial changes to the qubit emission rate. Further, upon addition of a reflective boundary to one end of the waveguide, we observe revivals in the qubit population on a timescale 30 times longer than the inverse of the qubit’s emission rate, corresponding to the round-trip travel time of an emitted photon. By tuning of the qubit-waveguide interaction strength, we probe a crossover between Markovian and non-Markovian qubit emission dynamics. These attributes allow for future studies of multi-qubit circuits coupled to structured reservoirs, in addition to constituting the necessary resources for generation of multiphoton highly entangled states.
arxiv pdf