**题目**: [理论室报告] On the Nature of Temperature: Classical Temperature of quantum materials versus Quantum temperature of classical black holes

**时间**: 2024年04月16日 14:00

**报告人**: Jinwu Ye

Great Bay University

**Abstract: **

What is nature of time remains the most important problem in Nature. Here we address a closely related but much simpler problem: what is the nature of temperature. Temperature is the concept unifying different branches of physics such as condensed matter physics, particle physics, quantum black holes and quantum information science. There are two kinds of temperature. One is the classical temperature which describes the thermal motion of the quantum material or particle physics experiments. It is determined by an external reservoir or self-determined in a canonical or micro-canonical ensemble respectively, does not contain $ \hbar $ explicitly and remains finite in the $ \hbar \to 0 $ limit. Another one is the quantum temperature which describes the quantum entanglement between the black hole interior and exterior. It is determined by the geometry of a black hole near its horizon ( so also called Hawking temperature ),contains $ \hbar $ explicitly and vanishes in the $ \hbar \to 0 $ limit. In the former case, when the sample is moving, its temperature stays the same in a micro-canonical ensemble, but increases in a canonical ensemble,independent of any observer. In the latter case, when the black hole is moving, its temperature stays the same to a distant observer, but increases when it moves closer to the observer. The Tolman effect is also reformulated as the quantum entanglement temperature. It is AdS/CFT which establishes the connections between the two temperatures. A full quantum theory of gravity is needed to unify the two temperatures into a unique one. The implications on the Eigenstate Thermalization Hypothesis (ETH), astronomical black holes in an expanding universe and two coupled Sachdev-Ye-Kitaev models to simulate a transversal wormhole are given. The experimental detections of these novel effects are discussed.

**Introduction of the speaker：**

Prof. Ye received Ph.D from Yale University. Currently, he is a chair professor at the newly found Great Bay university in Dongguan, Guangdong, China. He is a condensed matter theorist working on the interdisciplinary field of condensed matter, quantum optics, cold atoms, non-relativistic quantum field theory. Recently, he has been particularly interested to explore possible deep connections among quantum/topological phases, Sachdev-Ye-Kitaev models and quantum black holes from material's point of views.

Address: M830

Inviter：Wuming Liu（82649249）