Emergent Hawking Radiation and Quantum Sensing in a Quenched Chiral Spin Chain

TL;DR

This paper studies how Hawking radiation can be simulated and detected in a 1D chiral spin chain undergoing a quantum quench, analyzing the radiation spectrum and quantum sensor responses.

Contribution

It introduces a method to detect Hawking radiation in a spin chain model using localized detectors and qubits, highlighting the conditions for faithful temperature sensing.

Findings

Radiation spectrum shows greybody-like deviations from ideal Planckian form.

Qubit sensors accurately measure Hawking temperature in weak-coupling regime.

Strong coupling causes qubits to thermalize with the environment, masking Hawking signals.

Abstract

We investigate the emergence and detection of Hawking radiation (HR) in a 1D chiral spin chain model, where the gravitational collapse is simulated by a sudden quantum quench that triggers a horizon-inducing phase transition. While our previous work Jaiswal [2025] established that this model mimics BH formation conditions even when the Hoop conjecture is seemingly violated, we here focus on the resulting stationary radiation spectrum and its detectability. By mapping the spin chain dynamics to a Dirac fermion in a curved (1 + 1)-dimensional spacetime, we analyze the radiation using two complementary approaches: field-theoretic modes and operational quantum sensors. First, using localized Gaussian wave packets to model realistic detectors, we find that the radiation spectrum exhibits deviations from the ideal Planckian form, analogous to frequency-dependent greybody factors, while retaining robust Poissonian statistics that signal the loss of formation-scale information. Second, we introduce a qubit coupled to the chain as a stationary Unruh-DeWitt detector. We demonstrate that the qubit functions as a faithful quantum sensor of the Hawking temperature only in the weak-coupling regime, where its population dynamics are governed solely by the bath spectral density. In the strong-coupling limit, the probe thermalizes with the global environment, obscuring the horizon-induced thermal signature. These results provide a clear operational protocol for distinguishing genuine analog HR from environmental noise in quantum simulation platforms.