Designing Optical Quantum Computing with Minimal Hardware

Abstract

Photons, while indispensable for quantum communication and metrology, fall short due to limited photon-photon interactions, thus suboptimal for quantum computing. This thesis explores the use of an atom-photon interface to foster entanglement between photons, thereby facilitating more scalable optical quantum computing with reduced resource demands. I initially discuss the deterministic generation of multi-dimensional cluster states via an atom-photon interface and time-delay feedback. These cluster states are essential resources for fault-tolerant measurement-based quantum computing. A diagrammatic method is introduced to derive tensor networks of highly entangled states, thereby aiding in the simulation of states produced from sequential photons. Subsequently, I investigate the implementation of the optical quantum Fourier transform through the interface, which facilitates photon-photon interactions and significantly reduces the dependence on linear optical devices. In addition to devising techniques, I introduce an error metric for non-trace-preserving quantum operations that aligns with fault-tolerant quantum computing theory. This metric is beneficial for assessing errors across various quantum platforms and post-selected protocols. Overall, this research advances the field of optical quantum information processing, proposing scalable, practical solutions for quantum computing. Concurrently, it pioneers novel error metrics, providing a promising benchmarking and optimization strategy for robust quantum information processing.