T. A. Ohki

Quantum–Classical Interface Based on Single Flux Quantum Digital Logic

  1. R. McDermott,
  2. M.G. Vavilov,
  3. B. L. T. Plourde,
  4. F.K. Wilhelm,
  5. P. J. Liebermann,
  6. O. A. Mukhanov,
  7. and T. A. Ohki
We describe an approach to the integrated control and measurement of a large-scale superconducting multiqubit circuit using a proximal coprocessor based on the Single Flux Quantum (SFQ)
digital logic family. Coherent control is realized by irradiating the qubits directly with classical bitstreams derived from optimal control theory. Qubit measurement is performed by a Josephson photon counter, which provides access to the classical result of projective quantum measurement at the millikelvin stage. We analyze the power budget and physical footprint of the SFQ coprocessor and discuss challenges and opportunities associated with this approach.
arxiv pdf

First-order sideband transitions with flux-driven asymmetric transmon qubits

  1. J. D. Strand,
  2. Matthew Ware,
  3. Félix Beaudoin,
  4. T. A. Ohki,
  5. B. R. Johnson,
  6. Alexandre Blais,
  7. and B. L. T. Plourde
We demonstrate rapid, first-order sideband transitions between a superconducting resonator and a frequency-modulated transmon qubit. The qubit contains a substantial asymmetry between
its Josephson junctions leading to a linear portion of the energy band near the resonator frequency. The sideband transitions are driven with a magnetic flux signal of a few hundred MHz coupled to the qubit. This modulates the qubit splitting at a frequency near the detuning between the dressed qubit and resonator frequencies, leading to rates up to 85 MHz for exchanging quanta between the qubit and resonator.
arxiv pdf