Photonic Simulation of Entanglement Growth After a Spin Chain Quench

TL;DR

This paper demonstrates the first experimental simulation of entanglement growth in a quantum spin chain using integrated photonic chips, confirming the volume law of entanglement growth and showcasing photonics as a tool for quantum device optimization.

Contribution

It introduces a digital photonic simulation of spin chain dynamics that verifies the volume law of entanglement growth experimentally for the first time.

Findings

Confirmed volume law growth of entanglement in a simulated spin chain.

Used two photonic chips to engineer and measure entanglement.

Showcased photonic circuits as a platform for quantum simulation and optimization.

Abstract

The time evolution of quantum many-body systems is one of the least understood frontiers of physics. The most curious feature of such dynamics is, generically, the growth of quantum entanglement with time to an amount proportional to the system size (volume law) even when the interactions are local. This phenomenon, unobserved to date, has great ramifications for fundamental issues such as thermalisation and black-hole formation, while its optimisation clearly has an impact on technology (e.g., for on-chip quantum networking). Here we use an integrated photonic chip to simulate the dynamics of a spin chain, a canonical many-body system. A digital approach is used to engineer the evolution so as to maximise the generation of entanglement. The resulting volume law growth of entanglement is certified by constructing a second chip, which simultaneously measures the entanglement between multiple distant pairs of simulated spins. This is the first experimental verification of the volume law and opens up the use of photonic circuits as a unique tool for the optimisation of quantum devices.