Monday, 12 January, 2026
at Lise Meitner Lecture Hall, University of Vienna
Boltzmanngasse 5, 1090 Wien

Classical and Qantum Simulation at Infinite Temperature: Coherent Quantum Dynamics and Dynamical Phase Transitions

Is infinite temperature matter classical and trivial? In contrast to naive expectations, quantum systems at infinite temperature display truly fascinating dynamics.

Infinite temperature states are much more common than they appear; subsystems of infinite Haar-random pure states are typically close to maximal entanglement, and correspond to an infinite temperature state.

Using quantum computers, it is now possible to explore the structure of infinite temperature states and study full counting statistics and quantum correlations in great detail. Recent Google experiments [1] simulated the dynamics of infinite temperature one-dimensional spin chains and demonstrated anomalous quantum diffusion and a dynamical phase transition. The recently developed quantum generating function (QGF) method [2] has allowed us to access time scales hitherto inaccessible to state-of-the-art classical and quantum simulations and shed light on the structure of the critical anomalous diffusion [3].

Infinite temperature interacting fermions also host intriguing coherent dynamics: in the interacting Hubbard chain, for example, anomalous diffusion appears in both spin and charge due to hidden non-Abelian symmetries [3]. At strong interactions, doublons are stabilized. They retain their coherence [4] and display Bloch oscillations. Furthermore, a curious spinless particle emerges at strong interactions and carries quantum information ballistically even at infinite temperature [5].

[1] E. Rosenberg et al., Dynamics of magnetization at infinite temperature in a Heisenberg spin chain, Science 384, 48–53 (2024).

[2]A. Valli, C.P. Moca, M.A. Werner, M. Kormos, Z. Krajnik, T. Prosen, G. Zaránd, Efficient computation of cumulant evolution and full counting statistics: application to infinite temperature quantum spin chains, Phys. Rev. Lett. 135, 100401 (2025).

[3] C.P. Moca, B. Dóra, D. Sticlet, A. Valli, T. Prosen, G. Zaránd, Dynamic scaling and Family-Vicsek universality in SU(N) quantum spin chains, arXiv:2503.21454 [Phys. Rev. B, in print].

[4] C.P. Moca, B. Dóra, G. Zaránd, Hot but Coherent: Doublons at Infinite Temperature in the Hubbard chain, arXiv:2509.20504.

[5] P. Penc, C.P. Moca, Ö. Legeza, T. Prosen, G. Zaránd, M.A. Werner, Loss-induced quantum information jet in an infinite temperature Hubbard chain, Phys. Rev. Lett. 133, 190403 (2024).

Host: Maksym Serbyn

You can follow this talk via zoom

Program

16:45 Get Together with Snacks

17:15 VCQ Student Talk

17:30 VCQ Colloquium Talk