Quantum Gate and Quantum State Preparation through Neighboring Optimal Control
Successful implementation of a fault-tolerant quantum computation on a system of qubits places severe demands on the hardware used to control the many-qubit state. It is known that an accuracy threshold Pa exists for any quantum gate that is to be used in such a computation. Specifically, the error probability Pe for such a gate must fall below the accuracy threshold: Pe< Pa. Estimates of Pa vary widely, though Pa∼ 10−4 has emerged as a challenging target for hardware designers. We present a theoretical framework based on neighboring optimal control that takes as input a good quantum gate and returns a new gate with better performance. We illustrate this approach by applying it to all gates in a universal set of quantum gates produced using non-adiabatic rapid passage that has appeared in the literature. Performance improvements are substantial, both for ideal and non-ideal controls. Under suitable conditions detailed below, all gate error probabilities fall well below the target threshold of 10−4.
Dissertation Committee Chair: Prof. Victor Yakovenko
Dr. Frank Gaitan
Dr. Christopher Lobb
Dr. Frederick Wellstood
Dr. Jacob Taylor
Dr. Christopher Jarzynski