Epidemic growth and Griffiths effects on an emergent network of excited atoms published in Nat. Commun.

Epidemic growth and Griffiths effects on an emergent network of excited atoms published in Nat. Commun.

We have discovered a striking correspondence between the excitation dynamics of a laser driven gas of Rydberg atoms and the spreading of diseases, which in turn opens up a controllable platform for studying non-equilibrium dynamics on complex networks.

We show that the competition between facilitated excitation and spontaneous decay of Rydberg excitations results in sub-exponential growth of the excitation number, which is empirically observed in real epidemics. The observed dynamics follow a power-law time dependence that parallels that which is empirically observed in real-world epidemics, providing a powerful demonstration of universality reaching beyond physics; (ii) a full description and interpretation of the experiment in terms of an emergent susceptible-infected-susceptible network linking the observed macroscopic dynamics to the microscopic physics; and (iii) the unexpected presence of rare region effects and a dynamical Griffiths phase (9–11) associated to the emergent network structure, which gives rise to critical dynamics over an extended parameter regime and explains the appearance of power-law growth and relaxation, but with non-universal exponents.

T. M. Wintermantel, M. Buchhold, S. Shevate et al.
Epidemic growth and Griffiths effects on an emergent network of excited atoms.
Nat. Commun. 12, 103 (2021).