Loop Quantum Photonic Chip for Coherent Multi-Time-Step Evolution

TL;DR

This paper introduces a loop quantum photonic chip that enables efficient, multi-step quantum simulations by reusing resources and minimizing loss, demonstrated through spin-boson model dynamics on a silicon nitride chip.

Contribution

The work presents a novel loop-based photonic chip design that supports scalable multi-step quantum evolution without reconfiguration or multiple tomography steps.

Findings

Successfully simulated three-step unitary evolution of the spin-boson model.

Achieved close agreement between experimental results and theoretical predictions.

Demonstrated low-loss, dynamic routing in a silicon nitride integrated photonic platform.

Abstract

Quantum evolution is crucial for the understanding of complex quantum systems. However, current implementations of time evolution on quantum photonic platforms are limited by both low photon generation efficiency and high propagation loss, making photon detection difficult. Furthermore, the single-layer complexity of most implementations cannot support multi-step quantum simulations. In this work, we present a loop quantum photonic chip (Loop-QPC) designed to efficiently simulate quantum dynamics over multiple time steps in a single chip. Our approach employs a recirculating loop structure to reuse computational resources and eliminate the need for multiple quantum tomography steps or chip reconfigurations. A cycle-or-measure circuit at the input and output stages allows dynamic routing of photons between evolution and measurement, enabling efficient control over the simulation loop and minimizing loss. We experimentally demonstrate the dynamics of the spin-boson model on a low-loss Silicon Nitride integrated photonic chip. The Loop-QPC achieves a three-step unitary evolution closely matching the theoretical predictions. These results establish the Loop-QPC as a promising method for efficient and scalable quantum simulation, advancing the development of quantum simulation on programmable photonic circuits.