Optimized Coplanar Waveguide Resonators for a Superconductor-Atom Interface

  1. M. A. Beck,
  2. J. A. Isaacs,
  3. D. Booth,
  4. J. D. Pritchard,
  5. M. Saffman,
  6. and R. McDermott
We describe the design and characterization of superconducting coplanar waveguide cavities tailored to facilitate strong coupling between superconducting quantum circuits and single
trapped Rydberg atoms. For initial superconductor-atom experiments at 4.2 K, we show that resonator quality factors above 104 can be readily achieved. Furthermore, we demonstrate that the incorporation of thick-film copper electrodes at a voltage antinode of the resonator provides a route to enhance the zero-point electric fields of the resonator in a trapping region that is 40 μm above the chip surface, thereby minimizing chip heating from scattered trap light. The combination of high resonator quality factor and strong electric dipole coupling between the resonator and the atom should make it possible to achieve the strong coupling limit of cavity quantum electrodynamics with this system.

Hybrid Atom–Photon Quantum Gate in a Superconducting Microwave Resonator

  1. J. D. Pritchard,
  2. J. A. Isaacs,
  3. M. A. Beck,
  4. R. McDermott,
  5. and M. Saffman
We propose a novel hybrid quantum gate between an atom and a microwave photon in a superconducting coplanar waveguide cavity by exploiting the strong resonant microwave coupling between
adjacent Rydberg states. Using experimentally achievable parameters gate fidelities >0.99 are possible on sub-μs timescales for waveguide temperatures below 40 mK. This provides a mechanism for generating entanglement between two disparate quantum systems and represents an important step in the creation of a hybrid quantum interface applicable for both quantum simulation and quantum information processing.