Super-compact universal quantum logic gates with inversedesigned elements

TL;DR

This paper demonstrates the design and fabrication of ultra-compact quantum logic gates on silicon chips using inverse design, significantly reducing their size and enabling scalable quantum photonic circuits.

Contribution

It introduces the smallest optical quantum gates to date, fabricated via inverse design, and shows their integration into larger quantum circuits for scalable quantum information processing.

Findings

Controlled-NOT and Hadamard gates are nearly a vacuum wavelength in size.

Cascaded gates enable arbitrary quantum processing on a much smaller scale.

The approach significantly reduces the size of quantum photonic circuits.

Abstract

Integrated quantum photonic circuit is a promising platform for the realization of quantum information processing in the future. To achieve the largescale quantum photonic circuits, the applied quantum logic gates should be as small as possible for the high-density integration on chips. Here, we report the implementation of super-compact universal quantum logic gates on silicon chips by the method of inverse design. In particular, the fabricated controlled-NOT gate and Hadamard gate are both nearly a vacuum wavelength, being the smallest optical quantum gates reported up to now. We further design the quantum circuit by cascading these fundamental gates to perform arbitrary quantum processing, where the corresponding size is about several orders smaller than that of previous quantum photonic circuits. Our study paves the way for the realization of largescale quantum photonic chips with integrated sources, and can possess important applications in the field of quantum information processes.