title: Robust quantum control using smooth pulses and topological winding.
abstract: The greatest challenge in achieving the high level of control needed for future technologies based on coherent quantum systems is the decoherence induced by the environment. Here, we present an analytical approach that yields explicit constraints on the driving field which are necessary and sufficient to ensure that the leading-order noise-induced errors in a qubit's evolution cancel exactly. We derive constraints for two of the most common types of noise that arise in qubits: slow fluctuations of the qubit energy splitting and fluctuations in the driving field itself. By theoretically recasting a phase in the qubit's wavefunction as a topological winding number, we can satisfy the noise-cancelation conditions by adjusting driving field parameters without altering the target state or quantum evolution. We demonstrate our method by constructing robust quantum gates for two types of spin qubit: phosphorous donors in silicon and nitrogen-vacancy centers in diamond.
authors.affiliation: Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, MD 20742, USA.|Joint Quantum Institute, University of Maryland, College Park, MD 20742, USA.
authors.forename: Edwin
authors.initials: E
authors.lastname: Barnes
authors.affiliation: Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong SAR, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, MD 20742, USA.|Joint Quantum Institute, University of Maryland, College Park, MD 20742, USA.
authors.forename: S
authors.initials: S
authors.lastname: Das Sarma