25th June 2020
Third order nonlinearities have long been used to power parametrically-driven microwave amplifiers for measurement of superconducting qubits. I will present two new experiments which adapt the same parametric drives to control and couple transmon qubits and high-Q cavities. In both cases, the three-wave couplings in the system are created in a flux-biased, SNAIL-based resonator, which is dispersively coupled to the objects to be controlled. Analogous to standard circuit-QED techniques with fourth-order Kerr terms, this creates a network of self- and cross-couplings among all the modes involved. By driving the SNAIL at the sum or difference frequency of a pair of modes we can create/destroy pairs of photons, swap photons between modes, or even drive both processes at the same time. Using this technique, we have realized a method which gives full control over both the steady state population/temperature and relaxation rate of a transmon qubit, as well as a 'router' which can connect four high-Q cavities with all-to-all swap gates.
Michael Hatridge received his B.S. in physics from Texas A&M University and his Ph.D. from U. C. Berkeley under the supervision of John Clarke. He is currently an Assistant Professor at the University of Pittsburgh. His research group, the Hatlab, builds quantum circuits for quantum information processing and exploring fundamental physics, especially of quantum measurement. He is the recipient of the 2019 NSF Career Award and a Sloan Fellowship (2020).
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