



01664nas a2200157   4500008004100000245006600041210006200107260001500169520119400184100001801378700001901396700001701415700001901432700001801451856003701469       2019                        eng d00aThe Speed of Quantum Information Spreading in Chaotic Systems0 aSpeed of Quantum Information Spreading in Chaotic Systems  c08/19/20193 a<p>We present a general theory of quantum information propagation in chaotic quantum many-body systems. The generic expectation in such systems is that quantum information does not propagate in localized form; instead, it tends to spread out and scramble into a form that is inaccessible to local measurements. To characterize this spreading, we define an information speed via a quench-type experiment and derive a general formula for it as a function of the entanglement density of the initial state. As the entanglement density varies from zero to one, the information speed varies from the entanglement speed to the butterfly speed. We verify that the formula holds both for a quantum chaotic spin chain and in field theories with an AdS/CFT gravity dual. For the second case, we study in detail the dynamics of entanglement in two-sided Vaidya-AdS-Reissner-Nordstrom black branes. We also show that, with an appropriate decoding process, quantum information can be construed as moving at the information speed, and, in the case of AdS/CFT, we show that a locally detectable signal propagates at the information speed in a spatially local variant of the traversable wormhole setup.</p>1 aCouch, Josiah1 aEccles, Stefan1 aNguyen, Phuc1 aSwingle, Brian1 aXu, Shenglong  uhttps://arxiv.org/abs/1908.06993