Hannover 2016 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 14: Ultracold Atoms, Ions and Molecules III (with Q)

A 14.8: Vortrag

Dienstag, 1. März 2016, 12:45–13:00, f342

Multicritical behaviour in dissipative Ising models — •Vincent Overbeck¹, Mohammad Maghrebi², Alexey Gorshkov², and Hendrik Weimer¹ — ¹Institut für Theoretische Physik, Leibniz Universität Hannover, Deutschland — ²Joint Quantum Institute, NIST/University of Maryland, College Park, MD, USA

Stationary states of dissipative quantum many-body systems are of great interest, having the possibility to undergo dissipative phase transitions that are fundamentally different from thermal equilibrium. We consider a dissipative extension of the Ising model, where the dissipation preserves the Z₂ symmetry. Using a variational approach [1,2], we find a second order and a first order phase transition line, which meet at a multicritical point that is not found in the equilibrium case. We make an analysis of the full phase diagram, discussing in detail the role of fluctuations in this model. Finally, we present a possible experimental realization based on Rydberg-dressed spin interactions.

[1] H. Weimer, Variational Principle for Steady States of Dissipative Quantum Many-Body Systems, Phys. Rev. Lett. 114, 040402 (2015).

[2] H. Weimer, Variational analysis of driven-dissipative Rydberg gases, Phys. Rev. A 91, 063401 (2015).