Fault-tolerant quantum computation with static linear optics

TL;DR

This paper introduces a topologically error-corrected photonic quantum computing architecture that eliminates the need for inline squeezing and reconfigurability, simplifying implementation and improving fault tolerance.

Contribution

It proposes a static linear optics setup for fault-tolerant quantum computing with GKP qubits, reducing overheads and combining noise effects for better threshold estimates.

Findings

Eliminates inline squeezing and reconfigurability requirements.

Uses a static optical circuit with probabilistic GKP sources.

Provides improved fault-tolerance thresholds.

Abstract

The scalability of photonic implementations of fault-tolerant quantum computing based on Gottesman-Kitaev-Preskill (GKP) qubits is injured by the requirements of inline squeezing and reconfigurability of the linear optical network. In this work we propose a topologically error-corrected architecture that does away with these elements at no cost - in fact, at an advantage - to state preparation overheads. Our computer consists of three modules: a 2D array of probabilistic sources of GKP states; a depth-four circuit of static beamsplitters, phase shifters, and single-time-step delay lines; and a 2D array of homodyne detectors. The symmetry of our proposed circuit allows us to combine the effects of finite squeezing and uniform photon loss within the noise model, resulting in more comprehensive threshold estimates. These jumps over both architectural and analytical hurdles considerably expedite the construction of a photonic quantum computer.