Quantum Optical Simulator for Unruh-DeWitt Detector Dynamics

TL;DR

This paper introduces a photonic platform using entangled nonlinear biphoton sources to simulate relativistic detector-field interactions, enabling tabletop exploration of phenomena like Unruh effect and quantum entanglement.

Contribution

It maps the Unruh-DeWitt detector model onto a quantum-optical system with phase-controlled biphoton sources, providing an experimentally feasible quantum simulator for relativistic quantum field effects.

Findings

Analytical solutions for signal photon number and correlation functions.

Numerical simulations show phase-dependent biphoton dynamics reproduce Unruh-DeWitt behavior.

Output states have tunable fidelity, interference, and entanglement based on seeding parameters.

Abstract

We present a quantum-optical platform for simulating relativistic detector-field interactions using entangled nonlinear biphoton sources (ENBSs), realized through phase-controlled single-photon frequency-comb (SPFC) sources. By mapping the dynamical evolution of this system onto the Unruh-DeWitt (UDW) detector model, we show that signal-mode excitations emulate detector transitions driven by vacuum fluctuations, while coherently seeded idler modes act as an effective quantum field. This correspondence enables tabletop exploration of Unruh-like excitation, coherence harvesting, and field-induced entanglement. We derive the effective interaction Hamiltonian and Lindblad master equation for two coherently seeded ENBS units and obtain analytical solutions for the signal photon number \(N_{\rm sig}(t)\) and second-order correlation function \(g^{(2)}(0;t)\). Numerical simulations confirm that phase-dependent biphoton dynamics reproduce UDW-type behavior, including tunable excitation and quantum correlations. The output signal state exhibits controllable fidelity, interference visibility, and entanglement entropy as functions of the seeding phase and amplitude. These results establish ENBSs as experimentally accessible quantum simulators of relativistic field phenomena, providing a photonic testbed for analog gravitational effects, vacuum fluctuations, and spacetime-induced coherence-all within reach of current nonlinear-optics technology.