Demonstration of a loop-based single-mode photonic quantum processor for general-purpose applications

Abstract

A quantum processor to import, process, and export optical quantum states is a common core technology enabling various photonic quantum information processing. However, there has been no photonic processor which is simultaneously universal, scalable, and programmable. Here, we report on an original loop-based single-mode versatile photonic quantum processor which is designed to be universal, scalable, and programmable. Our processor can perform arbitrarily many steps of programmable quantum operations on a given single-mode optical quantum state by time-domain processing in a dynamically controlled loop-based optical circuit. We use this processor to demonstrate programmable single-mode Gaussian gates and multi-step squeezing gates. In addition, we prove that the processor can perform universal quantum operations by injecting appropriate ancillary states and also be straightforwardly extended to a multi-mode processor. These results show that our processor is programmable, scalable, and potentially universal, leading to be suitable for general-purpose applications.

Building a large-scale quantum computer with continuous-variable optical technologies

“…A later experiment updated this circuit to a single-mode photonic quantum processor in Fig. 7(b), demonstrating programmable and multi-step Gaussian operations [110]. This demonstration included optical feedforward that was omitted in the time-multiplexed one-way QC experiments [29,30].…”

“…Instead, these cavities limit the bandwidth of the generated squeezed states. For example, typical ring-cavity OPOs used in state-of-the-art timemultiplexed experiments [29,31,110,112] have only 65 MHz bandwidth [115], which mainly limited the computational speed of these experiments. The bandwidth can be broader by fabricating smaller cavities but has been limited to around 2 GHz even with a monolithically integrated OPO [116].…”