Deterministic generation of shaped single microwave photons using a parametrically driven coupler

  1. Jiaying Yang,
  2. Axel Eriksson,
  3. Mohammed Ali Aamir,
  4. Ingrid Strandberg,
  5. Claudia Castillo Moreno,
  6. Daniel Perez Lozano,
  7. Per Persson,
  8. and Simone Gasparinetti
A distributed quantum computing system requires a quantum communication channel between spatially separated processing units. In superconducting circuits, such a channel can be realized
by using propagating microwave photons to encode and transfer quantum information between an emitter and a receiver node. Here we experimentally demonstrate a superconducting circuit that deterministically transfers the state of a data qubit into a propagating microwave mode, with a process fidelity of 94.5%. We use a time-varying parametric drive to shape the temporal profile of the propagating mode to be time-symmetric and with constant phase, so that reabsorption by the receiving processor can be implemented as a time-reversed version of the emission. We demonstrate a self-calibrating routine to correct for time-dependent shifts of the emitted frequencies due to the modulation of the parametric drive. Our work provides a reliable method to implement high-fidelity quantum state transfer and remote entanglement operations in a distributed quantum computing network.

Resolving Fock states near the Kerr-free point of a superconducting resonator

  1. Yong Lu,
  2. Marina Kudra,
  3. Timo Hillmann,
  4. Jiaying Yang,
  5. Hangxi Li,
  6. Fernando QuijandrĂ­a,
  7. and Per Delsing
We have designed a tunable nonlinear resonator terminated by a SNAIL (Superconducting Nonlinear Asymmetric Inductive eLement). Such a device possesses a sweet spot in which the external
magnetic flux allows to suppress the Kerr interaction. We have excited photons near this Kerr-free point and characterized the device using a transmon qubit. The excitation spectrum of the qubit allows to observe photon-number-dependent frequency shifts about nine times larger than the qubit linewidth. Our study demonstrates a compact integrated platform for continuous-variable quantum processing that combines large couplings, considerable relaxation times and excellent control over the photon mode structure in the microwave domain.