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Title: Minimal coupling density preserving SYK chaos in sparse models
Plain: Removing most random couplings from SYK makes it easier to simulate on quantum hardware. It is unclear how many couplings can be removed before it stops behaving like a black hole.
Precise: In sparse Majorana SYK with $N$ fermions and k N four-body terms chosen at random, find the critical $k_c$ (as $N\to\infty$) below which the low-temperature Schwarzian regime and near-maximal Lyapunov exponent are lost, and the $1/k$ corrections above it. Answer: $k_c$, or the scaling of physical quantities with $k$.
Settled by: An analytic large-N treatment of sparse random hypergraphs plus large-N numerics of spectra and OTOCs at several k.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: open
Status note: (empty)
Posed since: 2020