AQC 2016 - Controlled Interactions Between Superconducting Qubits for Adiabatic Quantum Simulations

A Google TechTalk, June 28, 2016, presented by Stefan Filipp (IBM Research) ABSTRACT: The controlled realization of different types of interactions between qubits without compromising their coherence is essential for adiabatic and analog quantum simulations. In the context of superconducting quantum circuits, highest coherence has been achieved with qubits operated at a fixed frequency. This strategy avoids extra noise-sensitive controls, e.g. via SQUID loops, but inhibits controllable resonant interactions. Here, we present a coupling method between fixed-frequency transmon qubits based on the frequency modulation of an auxiliary capacitively coupled quantum bus. Different types of interactions, such as transverse XX- and YY-type interactions, and longitudinal ZZ-type interactions can be realized by an appropriate choice of the modulation frequency. Since the coupling bus remains in its ground state at all times, its coherence does not significantly influence the fidelity of gate operations resulting in iSWAP gate fidelities of 98%. With the possibility to simultaneously create interactions along different directions, this scheme is suited to engineer Hamiltonians with adjustable coupling terms, for instance to simulate fermionic quantum systems. N. Moll, IBM Research - Zurich, Switzerland, M. Roth, IBM Research - Zurich, Switzerland, I. Tavernelli, IBM Research - Zurich, Switzerland, A. Fuhrer, IBM Research - Zurich, Switzerland, P. Mueller, IBM Research - Zurich, Switzerland, D. McKay, IBM T. J. Watson Research Center, Yorktown Heights, US, Antonio Mezzacapo, IBM T. J. Watson Research Center, Yorktown Heights, US, Easwar Magesan, IBM T. J. Watson Research Center, Yorktown Heights, US, J. Chow, IBM T. J. Watson Research Center, Yorktown Heights, US, J. Gambetta, IBM T. J. Watson Research Center, Yorktown Heights, US Presented at the Adiabatic Quantum Computing Conference, June 26-29, 2016, at Google's Los Angeles office.