Investigating quantum correlations in collective emission of light using TWA simulations

Simulating large-scale quantum systems suffers from exponential complexity and is intractable for most cases in higher dimensions. The recently developed Truncated Wigner Approximation (TWA) for spins [1,2] is a powerful technique to simulate dissipative, interacting spin systems with a large number of spins taking into account leading-order quantum effects. Of special interest is the superradiant collective emission from atoms coupled to a waveguide, which can be described very well with our method [3]. We compute the second order correlation function of the emitted light and see a good agreement between the theoretical and experimental data for the superradiant bursts and the corresponding behavior of equal-time correlation functions. However, determining two-time correlations within phase space approaches is notoriously difficult. We here developed an efficient method to numerically calculate such multi-time-correlations of strongly coupled spins [4] and demonstrate its accuracy for different problems including experimental data from waveguide experiments.

[1,2] C. Mink et al., 10.21468/SciPostPhys.15.6.233, PhysRevRe-search.4.043136

[3] F. Tebbenjohanns et al., PhysRevA.110.043713

[4] J. Hartmann, M. Fleischhauer in preparation