Hybridization of pulse and continuous-wave based optical quantum computation

TL;DR

This paper proposes a hybrid optical quantum computing architecture combining pulsed and continuous-wave light to enable ultrafast, low-loss quantum state generation and measurement, demonstrated through ultrafast homodyne detection of single photons.

Contribution

It introduces a novel hybrid architecture leveraging pulsed and CW light for scalable, high-speed optical quantum computation, with a proof-of-principle ultrafast homodyne measurement demonstration.

Findings

Ultrafast homodyne measurement achieved with a 70 ps temporal width.

Measured Wigner function at the origin was -0.153±0.003, indicating non-classical states.

The architecture enables high-speed quantum information processing with low-loss manipulation.

Abstract

We propose a pulse and continuous wave (CW) hybrid architecture of continuous-variable measurement-based optical quantum computation utilizing the strengths of both pulsed and CW light. In this architecture, input and ancillary non-Gaussian quantum states necessary for fault-tolerance and universality are generated with pulsed light, whereas quantum processors including continuous-variable cluster states and homodyne measurement systems are operated with CW light. This architecture is expected to enable both generation of quantum states with shorter optical wavepackets for ultrafast computation and low-loss manipulation and measurement of these states. In this study, as a proof-of-principle, an ultrafast homodyne measurement using a CW local oscillator was performed on single-photon states generated with pulsed light. The measured single-photon state's temporal width was around 70 ps and the value of the Wigner function at the origin was $W(0,0) = -0.153\pm0.003$, which is highly non-classical. This will be a core technology for high-speed optical quantum information processing.