AQC 2016 - Floquet Quantum Annealing with Superconducting Circuit
6A Google TechTalk, June 29, 2016, presented by Oleksandr Kyriienko (Niels Bohr Institute)
ABSTRACT: The successful application of a quantum annealing procedure largely relies on the possibility to implement a non-trivial Hamiltonian in a fully controlled system. The circuit QED platform has shown a tremendous progress in this direction, demonstrating qubit chains with on-site effective magnetic fields being tunable in time along any chosen axis. At the same time, the inter-qubit interaction is typically limited to the isotropic XY model with nearest neighbor flip-flop process, which limits accessible types of Hamiltonian which can be simulated. Typically, surmounting of this restriction requires either construction of unconventional couplings between qubits or digitization of the evolution.
We propose to use Floquet dynamics to perform a quantum simulation with superconducting system. The algorithm relies on fast time modulation of an effective magnetic field for the qubits, such that the resulting time-averaged Floquet Hamiltonian is of the generic Heisenberg XYZ type, and is controllable by the drive parameters. As examples we show recipes for designing transverse Ising and non-stoquastic XYZ Hamiltonians, and perform annealing to the ground state of each configuration. Considering realistic parameters the procedure allows closely following the ideal continuous annealing, yielding a fidelity corresponding to the one achievable by digital evolution with many (greater than 20) Trotter steps.
The scheme does not require modification of existing circuit QED setups, potentially allows for diverse high fidelity quantum annealing with currently accessible system parameters, and can serve as simple yet reliable way towards quantum annealing with limited resources.
Anders S. Sørensen, Niels Bohr Institute
Presented at the Adiabatic Quantum Computing Conference, June 26-29, 2016, at Google's Los Angeles office.