



01495nas a2200181   4500008004100000245008500041210006900126260001400195490000800209520092100217100001901138700002101157700002701178700002301205700002001228700002801248856003701276       2023                        eng d00aCritical phase and spin sharpening in SU(2)-symmetric monitored quantum circuits0 aCritical phase and spin sharpening in SU2symmetric monitored qua  c8/17/20230 v1083 a<p>Monitored quantum circuits exhibit entanglement transitions at certain measurement rates. Such a transition separates phases characterized by how much information an observer can learn from the measurement outcomes. We study SU(2)-symmetric monitored quantum circuits, using exact numerics and a mapping onto an effective statistical-mechanics model. Due to the symmetry&#39;s non-Abelian nature, measuring qubit pairs allows for nontrivial entanglement scaling even in the measurement-only limit. We find a transition between a volume-law entangled phase and a critical phase whose diffusive purification dynamics emerge from the non-Abelian symmetry. Additionally, we numerically identify a &quot;spin-sharpening transition.&quot; On one side is a phase in which the measurements can efficiently identify the system&#39;s total spin quantum number; on the other side is a phase in which measurements cannot.</p>1 aMajidy, Shayan1 aAgrawal, Utkarsh1 aGopalakrishnan, Sarang1 aPotter, Andrew, C.1 aVasseur, Romain1 aHalpern, Nicole, Yunger  uhttps://arxiv.org/abs/2305.13356