@article{ISI:000399789300001,
 abstract = {We propose an extension of the Sachdev-Ye-Kitaev (SYK) model that
exhibits a quantum phase transition from the previously identified
non-Fermi-liquid fixed point to a Fermi-liquid-like state, while still
allowing an exact solution in a suitable large-N limit. The extended
model involves coupling the interacting N-site SYK model to a new set of
pN peripheral sites with only quadratic hopping terms between them. The
conformal fixed point of the SYK model remains a stable low-energy phase
below a critical ratio of peripheral sites p < p(c) (n) that depends on
the fermion filling n. The scrambling dynamics throughout the
non-Fermi-liquid (NFL) phase is characterized by a universal Lyapunov
exponent lambda(L) -> 2 pi T in the low-temperature limit; however, the
temperature scale marking the crossover to the conformal regime vanishes
continuously at the critical point p(c). The residual entropy at T -> 0,
nonzero in the NFL, also vanishes continuously at the critical point.
For p > p(c) the quadratic sites effectively screen the SYK dynamics,
leading to a quadratic fixed point in the low-temperature and
low-frequency limit. The interactions have a perturbative effect in this
regime leading to scrambling with Lyapunov exponent lambda(L) alpha T-2.},
 article-number = {134302},
 author = {Banerjee, Sumilan and Altman, Ehud},
 doi = {10.1103/PhysRevB.95.134302},
 eissn = {2469-9969},
 issn = {2469-9950},
 journal = {PHYSICAL REVIEW B},
 month = {APR 19},
 number = {13},
 title = {Solvable model for a dynamical quantum phase transition from fast to
slow scrambling},
 unique-id = {ISI:000399789300001},
 volume = {95},
 year = {2017}
}