Fast Scrambling at the Boundary
Ancel Larzul, Anirvan M. Sengupta, Antoine Georges, Marco Schir\`o

TL;DR
This paper analyzes quantum chaos in a multichannel Kondo impurity model, revealing maximal chaos at the boundary due to strong correlations and fractionalization, with exact low-temperature out-of-time-order correlator results.
Contribution
It provides the first exact computation of quantum chaos in a non-disordered, strongly correlated impurity model showing maximal chaos and fractionalization.
Findings
Lyapunov exponent linear in temperature as T→0
Maximal chaos occurs when N=K
Bosons and fermions reach half the maximal Lyapunov exponent
Abstract
Many-body systems which saturate the quantum bound on chaos are attracting interest across a wide range of fields. Notable examples include the Sachdev-Ye-Kitaev model and its variations, all characterised by some form or randomness and all to all couplings. Here we study many-body quantum chaos in a quantum impurity model showing Non-Fermi-Liquid physics, the overscreened multichannel Kondo model. We compute exactly the low-temperature behavior of the out-of time order correlator in the limit of large and large number of channels , at fixed ratio . Due to strong correlations at the impurity site the spin fractionalizes in auxiliary fermions and bosons. We show that all the degrees of freedom of our theory acquire a Lyapunov exponent which is linear in temperature as , with a prefactor that depends on . Remarkably, for the…
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Taxonomy
TopicsQuantum many-body systems · Quantum chaos and dynamical systems · Quantum and electron transport phenomena
