Title: Grüneisen Parameters: origin, identity and quantum refrigeration

Time: 10:00 a.m. Tuesday, May 14, 2019

Location: Conference Room 3016 Gezhi Building

In solid state physics, the Grüneisen parameter (GP), originally defined as a derivative of the crystal lattice frequency with respect to the volume of the system, can be widely used to quantify the spectrum properties induced by external potential changes. However, the GP is very little known for

quantum gases with interactions. In this talk, we will present general results of the GPs on its origin, new identity and applications in quantum gases of ultracold atoms. We prove that the scaling invariance of the entropy leads to a surprisingly sim-ple identity among the volume, magnetic field and interaction driven GPs, quantifying universal scalings of quantum fluctuations and interaction driven magnetocaloric effect in quantum gases. We also find that the entropy ac-cumulation near a quantum phase transition leads to a rapid reduction of temperature through an adiabatic change of either interaction or magnetic field. Thus the interaction ramp-up and -down provide a promising proto-col of quantum refrigeration in addition to the adiabatic demagnetization cooling. Using exactly Bethe ansatz solutions, we further confirm the above rigorous results of the GP and discuss the quantum heat engine and refrig-eration in one-dimensional Bose and Femi gases.