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arXiv · 2602.05322

More on OTOCs and Chaos in Quantum Mechanics -- Magnetic Fields

Cameron Beetar·Jeff Murugan
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Abstract

We revisit thermal out-of-time-order correlators (OTOCs) in single-particle quantum systems, focusing on magnetic billiards. Using the stadium billiard as a testbed, we compute the thermal OTOC $C_T(t) = -\langle [x(t), p]^2 \rangle_\beta$ and extract Lyapunov-like exponents $\lambda_L$ that quantify early-time growth. We map out $\lambda_L(T, B)$, revealing a crossover from quantum chaos to magnetic rigidity. In parallel, we compute an alternative OTOC built from guiding-center operators, which exhibits qualitatively distinct dynamics and no exponential growth. Our results offer a controlled framework for probing scrambling, temperature dependence, and the interplay of geometry and magnetic fields in quantum systems.

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Cameron Beetar, Jeff Murugan. 2026-02-05. More on OTOCs and Chaos in Quantum Mechanics -- Magnetic Fields. https://arxiv.org/abs/2602.05322

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