Efficient Simulation of Doppler-Broadened Rydberg Quantum Receivers via Monte Carlo Wave Functions

Abstract

Theoretical modeling of Rydberg atom-based microwave sensors is often limited by the high computational cost of the density matrix formalism (DMF), especially when resolving transient dynamics in Doppler-broadened vapor cells. We introduce an efficient direct time-domain numerical framework based on the Monte Carlo Wave Function (MCWF) method for Doppler-broadened Rydberg-atom simulations. By incorporating the Doppler effect as a stochastic initialization parameter within individual quantum trajectories, our approach naturally captures thermal broadening, thereby avoiding explicit velocity-grid integration in the MCWF calculation. This reformulates the propagation from a density-matrix representation whose state dimension scales quadratically with the number of levels to a trajectory-based wave-function representation with linear state dimension for each propagated trajectory. We demonstrate that this framework achieves nearly one order of magnitude reduction in runtime under comparable AT-splitting extraction accuracy, while maintaining agreement with the DMF results for the considered observables. The method is further applied to representative time-domain signal-recovery scenarios, including baseband symbol recovery for 8-ary amplitude-shift keying (8-ASK) signals. This work provides a scalable tool for designing and optimizing next-generation Rydberg quantum receivers.