Topological quantum walks in cavity-based quantum networks

TL;DR

This paper proposes a method to simulate topological phases using cavity-based quantum networks with single photons, enabling observation of boundary states and phase transitions, and demonstrating robustness to imperfections.

Contribution

It introduces a protocol for implementing discrete-time quantum walks and simulating topological insulator phases in cavity-based quantum networks.

Findings

Topological boundary states can be observed via photon density measurements.

Topological phase transitions are detectable in the system.

The topological signatures are robust against practical imperfections.

Abstract

We present a protocol to implement discrete-time quantum walks and simulate topological insulator phases in cavity-based quantum networks, where the single photon is the quantum walker and the cavity input-output process is employed to realize the state-dependent translation operation. Different topological phases can be simulated through tuning the single-photon polarization rotation angles. We show that both the topological boundary states and topological phase transitions can be directly observed via measuring the final photonic density distribution. Moreover, we also demonstrate that these topological signatures are quite robust to practical imperfections. Our work opens a new prospect using cavity-based quantum networks as quantum simulators to study discrete-time quantum walks and mimic condensed matter physics.