Speaker: Somnath Porey – B1950020 (research scholar, Dept. of Physics, RKMVERI)

Date: 17/02/2022, Time 4 pm

Venue: Dept. of Physics, Prajna, Bhavan

External Expert: Prof. Koushik Ray, IACS, Kolkata

Out-Of-Time-Ordered-Correlation functions (OTOCs) in thermal equilibrium has been used as a diagnostic of chaos in QFTs for times much smaller than the “scrambling time”.  In this talk, we will argue that the OTOCs continue to be a good diagnostic of chaos even when the system is out of equilibrium. As an explicit example, we study OTOC’s  in a class of periodically driven CFTs.  The drive profile  breaks time and spatial translational symmetry, Due to the lack of translational invariance, the OTOCs show some novel features such as an spatially dependent “butterfly velocity”. We compare and contrast the behaviour of the OTOCs with the case of the “undriven thermal CFT”.  We show that even in this non-equilibrium example, the OTOCs continue to demarcate chaotic and integrable CFTs.