Universal programmable photonic architecture for quantum information processing

TL;DR

This paper introduces a versatile photonic integrated circuit architecture that can be programmed to perform any quantum operation, enabling efficient quantum state preparation and circuit implementation with high fidelity.

Contribution

The paper presents a novel, fully programmable photonic quantum gate array architecture capable of implementing arbitrary quantum states and operators without hardware changes.

Findings

Able to prepare arbitrary quantum states and operators.

Gradient-based optimization achieves high-fidelity circuit approximations.

Device can implement any quantum circuit through phase adjustments.

Abstract

We present a photonic integrated circuit architecture for a quantum programmable gate array (QPGA) capable of preparing arbitrary quantum states and operators. The architecture consists of a lattice of phase-modulated Mach-Zehnder interferometers, which perform rotations on path-encoded photonic qubits, and embedded quantum emitters, which use a two-photon scattering process to implement a deterministic controlled-$\sigma_z$ operation between adjacent qubits. By appropriately setting phase shifts within the lattice, the device can be programmed to implement any quantum circuit without hardware modifications. We provide algorithms for exactly preparing arbitrary quantum states and operators on the device and we show that gradient-based optimization can train a simulated QPGA to automatically implement highly compact approximations to important quantum circuits with near-unity fidelity.