Speaker: Prof. Matthias Weidemüller
Title of Talk: Does an isolated quantum spin system thermalize?
Understanding how closed quantum systems dynamically approach thermal equilibrium presents a major unresolved problem in statistical physics. Generically, it is expected that non-integrable quantum systems thermalize as they comply with the Eigenstate Thermalization Hypothesis (ETH). A notable exception to this is the phenomenon of many-body localization, where the emergence of local conserved quantities prevents thermalization, which has been observed in finite low-dimensional systems. We study an ensemble of Heisenberg spins with a tunable distribution of random coupling strengths realized by a Rydberg quantum simulator. The total magnetization as a function of external field after a quench serves as a probe for thermalization, showing striking non-analytic behavior at zero field. We find that such an isolated quantum system exhibits a non-thermalizing regime despite being non-integrable. It is shown that thermalization can be restored by reducing the disorder in the coupling strengths. As our system consists of up to 4000 spins, we show that closed quantum systems can fail to reach thermal equilibrium even at system sizes approaching the thermodynamic limit.

Venue (HYBRID-EVENT): Goldene Box, Physikalisches Institut, INF 226, 69120 Heidelberg AND all talks will also be streamed via the permanent Zoom-link:

Meeting ID: 946 0240 1603
Passcode: 386993

13:00 – 13:45  talk
13:45-14:00   questions & discussion
14:00 pizza


The main idea of the CRC 1225 Lunch Seminars is to bring together all scientists involved in our collaboration on a regular basis to allow exchange and discussion even outside one’s own research topics. We therefore invite all PIs and working group members of the CRC 1225 ISOQUANT to participate in the Lunch Seminars and to use this opportunity for getting to know each other, fruitful discussions and valuable exchange.

The seminar will take place in presence in accordance with the current COVID-19 regulations for on-site events (Please wear a FFP2 mask or surgical mask if the minimum distance of 1.5m can not be guaranteed).