Quantum computers promise a new paradigm of computation where information is processed in a way that has no classical analogue. However, the known problems for which quantum computers offer a computational advantage, require long gate sequences and large number of qubits. Error-correction codes and fault-tolerant gate implementation require the encoding of logical qubits on a large number of physical qubits, and given the overheads, it is expected that general purpose quantum computers will have millions of physical qubits, thus requiring an underlying qubit technology that can be manufactured at scale. Photons make great qubits, they are cheap to produce, resilient to noise and the only known option for quantum networks. Most crucially, they can be efficiently manipulated with silicon photonics, an intrinsically scalable and manufacturable platform in which all the fundamental quantum gates can be implemented. In this talk, I will describe an architecture for universal fault-tolerant quantum computing based on linear optics, in the process I will explain how measurement-induced non-linearity can overcome the challenge of creating entanglement and how loss can be effectively tackled with error correcting codes.
Mercedes Gimeno-Segovia is Sr. Director of Quantum Architecture at PsiQuantum Corp. She received her PhD from Imperial College London for her work on linear optical quantum computing. After postdoctoral positions in Bristol (UK) and Calgary (Canada), she joined PsiQuantum in 2017, where she leads a team working on the design and development of an architecture for universal fault-tolerant quantum computing using silicon photonics. She is the author of the O'Reilly book "Programming Quantum Computers: Essential Algorithms and Code Samples".