Alexandre Blais

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

First-order sidebands in circuit QED using qubit frequency modulation

  1. Félix Beaudoin,
  2. Marcus P. da Silva,
  3. Zachary Dutton,
  4. and Alexandre Blais
Sideband transitions have been shown to generate controllable interaction between superconducting qubits and microwave resonators. Up to now, these transitions have been implemented
with voltage drives on the qubit or the resonator, with the significant disadvantage that such implementations only lead to second-order sideband transitions. Here we propose an approach to achieve first-order sideband transitions by relying on controlled oscillations of the qubit frequency using a flux-bias line. Not only can first-order transitions be significantly faster, but the same technique can be employed to implement other tunable qubit-resonator and qubit-qubit interactions. We discuss in detail how such first-order sideband transitions can be used to implement a high fidelity controlled-NOT operation between two transmons coupled to the same resonator.
arxiv pdf