How to Build a Large-Scale Optical Quantum Computer

Simon J. Devitt, Ashley M. Stephens, William J. Munro +1 more

In this paper we provide a review of the perpetual optical topological quantum computer, a large scale quantum architecture utilising a single quantum component. We will examine the building block of this architecture, the photonic module, the original architecture design and a modified design which allows for the entire computer to be constructed solely from a single component. Given the extraordinary specificity of this design we can provide a pessimistic resource analysis, utilising deliberately bad circuit designs and arrangements to determine the size and speed of a large scale factoring engine.

Ulrik L. Andersen

Jonathan P. Dowling, J. D. Franson, Hanho Lee +1 more

Kosuke Fukui, Shuntaro Takeda

Abstract Realizing a large-scale quantum computer requires hardware platforms that can simultaneously achieve universality, scalability, and fault tolerance. As a viable pathway to meeting these requirements, quantum computation (QC) based on continuous-variable optical systems has recently gained more attention due to its unique advantages and approaches. This review introduces several topics of recent experimental and theoretical progress in the optical continuous-variable QC that we believe are promising. In particular, we focus on scaling-up technologies enabled by time multiplexing, bandwidth broadening, and integrated optics, as well as hardware-efficient and robust bosonic quantum error-correction schemes.

Shuntaro Takeda, Akira Furusawa

Photonic quantum computing is one of the leading approaches to universal quantum computation. However, large-scale implementation of photonic quantum computing has been hindered by its intrinsic difficulties, such as probabilistic entangling gates for photonic qubits and lack of scalable ways to build photonic circuits. Here, we discuss how to overcome these limitations by taking advantage of two key ideas which have recently emerged. One is a hybrid qubit-continuous variable approach for realizing a deterministic universal gate set for photonic qubits. The other is the time-domain multiplexing technique to perform arbitrarily large-scale quantum computing without changing the configuration of photonic circuits. These ideas together will enable scalable implementation of universal photonic quantum computers in which hardware-efficient error correcting codes can be incorporated. Furthermore, all-optical implementation of such systems can increase the operational bandwidth beyond terahertz in principle, ultimately enabling large-scale fault-tolerant universal quantum computers with ultrahigh operation frequency.

Jonathan P. Dowling, J. D. Franson, Hugo Kyo Lee +1 more