## SCL Online Seminar by Milan Radonjić

You are cordially invited to the SCL online seminar of the Center for the Study of Complex Systems, which will be held on Thursday, 18 February 2021 at 14:00 on Zoom. The talk entitled

will be given by Dr. Milan Radonjić (Scientific Computing Laboratory, Center for the Study of Complex Systems, Institute of Physics Belgrade and Department of Physics, TU Kaiserslautern, Germany). Abstract of the talk:

In this talk we will consider a time-dependent extension of a perturbative mean-field approach to the homogeneous dirty boson problem by investigating how switching on and off a weak disorder potential affects the stationary state of an initially equilibrated Bose-Einstein condensate by the emergence of a disorder-induced condensate deformation. In the switch-on scenario, we will study if the stationary condensate deformation turns out to be a sum of an equilibrium part [1], that actually corresponds to adiabatically switching on the disorder, and a dynamically-induced part, where the latter depends on the particular driving protocol [2]. If the disorder is switched off afterwards, we will find out if the resulting condensate deformation acquires an additional dynamically-induced part in the long-time limit, and what happens with the equilibrium part. We will also present an appropriate generalization to inhomogeneous trapped condensates. Our results demonstrate that the condensate deformation represents an indicator of the generically non-equilibrium nature of steady states of a Bose gas in a temporally controlled weak disorder.

[1] K. Huang and H.-F. Meng, Phys. Rev. Lett. 69, 644 (1992)

[2] Milan Radonjić and Axel Pelster, SciPost Phys. 10, 008 (2021)

**Non-equilibrium evolution of Bose-Einstein condensate deformation in temporally controlled weak disorder**will be given by Dr. Milan Radonjić (Scientific Computing Laboratory, Center for the Study of Complex Systems, Institute of Physics Belgrade and Department of Physics, TU Kaiserslautern, Germany). Abstract of the talk:

In this talk we will consider a time-dependent extension of a perturbative mean-field approach to the homogeneous dirty boson problem by investigating how switching on and off a weak disorder potential affects the stationary state of an initially equilibrated Bose-Einstein condensate by the emergence of a disorder-induced condensate deformation. In the switch-on scenario, we will study if the stationary condensate deformation turns out to be a sum of an equilibrium part [1], that actually corresponds to adiabatically switching on the disorder, and a dynamically-induced part, where the latter depends on the particular driving protocol [2]. If the disorder is switched off afterwards, we will find out if the resulting condensate deformation acquires an additional dynamically-induced part in the long-time limit, and what happens with the equilibrium part. We will also present an appropriate generalization to inhomogeneous trapped condensates. Our results demonstrate that the condensate deformation represents an indicator of the generically non-equilibrium nature of steady states of a Bose gas in a temporally controlled weak disorder.

[1] K. Huang and H.-F. Meng, Phys. Rev. Lett. 69, 644 (1992)

[2] Milan Radonjić and Axel Pelster, SciPost Phys. 10, 008 (2021)