IQIM Postdoctoral and Graduate Student Seminar

Abstract: The complexity of quantum dynamics is at the heart of the power of quantum computers. In this talk, I will explore how this complexity arises during dynamics governed by a local Hamiltonian. As a key tool, I will introduce a cluster expansion that allows for tight accounting of locality constraints [1]. Bounding the truncation error of the cluster expansion leads to an efficient approximation algorithm at short times for both local observables and non-local quantities such as the Loschmidt echo. The algorithm outperforms simple approaches based on the Lieb–Robinson bound. To conclude, I will give a brief overview of complementary work that aims to maximize the utility of noisy quantum devices for quantum simulation [2, 3].

[1] D. S. Wild and Á. M. Alhambra, PRX Quantum 4, 020340 (2023).
[2] Y. Yang, A. Christianen, S. Coll-Vinent, V. Smelyanskiy, M. C. Bañuls, T. E. O'Brien, D. S. Wild, J. I. Cirac, PRX Quantum 4, 030320 (2023).
[3] Y. Yang, A. Christianen, M. C. Bañuls, D. S. Wild, J. I. Cirac, arXiv:2308.10796.

Lunch will be provided, following the talk, on the lawn north of the Bridge Building.