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Lee-Yang zeros at O(3) and deconfined quantum critical points. – (Jonathan D’Emidio / LPT / Seminar). – 12/12/2023, 14 H.
12 December 2023; 14h00 - 15h30
Jonathan D’Emidio (DIPC & Multiverse Computing, Saint-Sébastien)
Seminar LPT, 12/12/2023, 14H, 3R1, seminar room, 3rd floor
Lee-Yang theory, based on the study of zeros of the partition function, is widely regarded as a powerful and complementary approach to the study of critical phenomena and forms a foundational part of the theory of phase transitions. Its widespread use, however, is complicated by the fact that it requires introducing complex-valued fields that create an obstacle for many numerical methods, especially in the quantum case where very limited studies exist beyond one dimension. In this talk I will present a simple and statistically exact method to compute partition function zeros with general complex-valued external fields in the context of large-scale quantum Monte Carlo simulations. I will show the power of this approach by extracting critical exponents from the leading Lee-Yang zeros of 2D quantum antiferromagnets with a complex staggered field, focusing on the Heisenberg bilayer and square-lattice J-Q models. I will also show how to introduce a complex field that couples to valence bond solid order, giving rise to extended rings of zeros in the J-Q model with purely imaginary staggered and valence bond solid fields.
Eprint : https://arxiv.org/abs/2308.00575