High Energy Theory Seminar

In general quantum many-body systems, almost all the states in a fixed energy window are locally indistinguishable from the microcanonical ensemble. Such a state is called a typical state and satisfies entanglement volume law. Typical states play a crucial role in modern statistical physics. 

In this talk, we discuss the opposite topic. We consider atypical states which have only a very small amount of entanglement compared to typical states. While such low entanglement states are very rare, we will show that one can find sufficiently many low entanglement states to account for the leading order of the thermodynamic entropy in a holographic CFT and discuss its implication in black hole physics [1]. We will also argue that a similar result should hold in generic quantum many-body systems, by introducing a plausible conjecture. 

Moreover, we will present a theorem that tells us how to systematically (though not efficiently) construct low entanglement states in a fixed energy window. As an application, we will also briefly discuss its implication in efficiently simulating low-temperature equilibrium in 1D critical systems [2]. 

[1] ZW, Yasushi Yoneta, "Counting atypical black hole microstates from entanglement wedges", arxiv: 2211.11787
[2] Yuya Kusuki, Kotaro Tamaoka, ZW, Yasushi Yoneta, "Efficient Simulation of Low Temperature Physics in One-Dimensional Gapless Systems", arxiv: 2309.02519

The talk is in 469 Lauritsen.

Contact [email protected] for Zoom information.