# Hannover 2013 – wissenschaftliches Programm

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# A: Fachverband Atomphysik

## A 12: Ultracold plasmas and Rydberg atoms (with Q)

### A 12.5: Vortrag

### Montag, 18. März 2013, 17:45–18:00, E 415

**Crystallization of photons via light storage in Rydberg gases** — Johannes Otterbach^{1,2}, •Matthias Moos^{1}, Dominik Muth^{1}, and Michael Fleischhauer^{1} — ^{1}Fachbereich Physik and Forschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany — ^{2}Department of Physics, Harvard University, Cambridge, MA 02138, USA

Light exciting atoms to Rydberg states under conditions of electromagnetically induced transparency (EIT) can be described in terms of slow-light Rydberg-polaritons.
The strong interaction mediated by the Rydberg atoms can give rise to crystallization of photons, i.e., to density waves with long-range power-law correlations. In an 1D setting the low-energy physics can be described
by a Luttinger liquid model. When the corresponding Luttinger parameter *K* becomes smaller than 1/2, the density wave dominates the correlations marking the onset of crystallization. We calculate the *K* parameter by DMRG simulations and compare it to analytic approximations. We find that under typical slow-light conditions *K* is much larger than 1/2 and thus no crystalline order can emerge.
However, storing the polaritons in a stationary spin wave by switching off the control laser the effective mass and thus the kinetic energy vanish and *K* approaches zero. If the storage is done sufficiently adiabatic, long range crystalline order can be generated.
We analyze the dynamics of this build-up in terms of a time-dependent Luttinger theory and derive conditions for an optimal storage scenario.