Heterogeneous Quantum Information Processing

Abstract

Quantum computations and quantum communications aim to use the laws of quantum mechanics to process information beyond the fundamental limits of classical computers. However, two obstacles remain toward practical large-scalequantum technologies. The first is the presence of noise in qubits and the second is the huge overhead in the number of physical qubits required for useful tasks. If not properly handled, noise can turn the outcome of quantum information processing into random classical bits, while current large qubit overhead requirements makes useful quantum technologies a far-reaching goal. A promising approach to tackling noise is quantum error correction which aims to reduce the rate of errors via encoding the quantum information over many physical qubits that are collectively called the logical qubits. However, quantum error correction requires a large overhead in the required number of physical qubits. In this thesis, we propose solutions to both problems. We demonstrate both theoretically and experimentally that the detailed knowledge of the noise processes in qubits can be utilized to reduce the errors on both physical and logical gates. In particular, we demonstrate that using physical qubits of distinct types can reduce the qubit overhead of fault-tolerant quantum computation.