



02215nas a2200169   4500008004100000245006400041210006300105260001300168490000700181520171100188100002101899700002101920700002701941700002001968700002001988856003702008       2021                        eng d00aEntanglement Phase Transitions in Measurement-Only Dynamics0 aEntanglement Phase Transitions in MeasurementOnly Dynamics  c1/2/20210 v113 a<p>Unitary circuits subject to repeated projective measurements can undergo an entanglement phase transition (EPT) as a function of the measurement rate. This transition is generally understood in terms of a competition between the scrambling effects of unitary dynamics and the disentangling effects of measurements. We find that, surprisingly, EPTs are possible even in the absence of scrambling unitary dynamics, where they are best understood as arising from measurements alone. This motivates us to introduce \emph{measurement-only models}, in which the &quot;scrambling&quot; and &quot;un-scrambling&quot; effects driving the EPT are fundamentally intertwined and cannot be attributed to physically distinct processes. This represents a novel form of an EPT, conceptually distinct from that in hybrid unitary-projective circuits. We explore the entanglement phase diagrams, critical points, and quantum code properties of some of these measurement-only models. We find that the principle driving the EPTs in these models is \emph{frustration}, or mutual incompatibility, of the measurements. Suprisingly, an entangling (volume-law) phase is the generic outcome when measuring sufficiently long but still local (≳3-body) operators. We identify a class of exceptions to this behavior (&quot;bipartite ensembles&quot;) which cannot sustain an entangling phase, but display dual area-law phases, possibly with different kinds of quantum order, separated by self-dual critical points. Finally, we introduce a measure of information spreading in dynamics with measurements and use it to demonstrate the emergence of a statistical light-cone, despite the non-locality inherent to quantum measurements.</p>1 aIppoliti, Matteo1 aGullans, Michael1 aGopalakrishnan, Sarang1 aHuse, David, A.1 aKhemani, Vedika  uhttps://arxiv.org/abs/2004.09560