Quantum Physics

I will present a universal numerical tool for identifying optimal adaptive metrological protocols in the presence of both uncorrelated and correlated noise [arXiv:2403.04854]. Leveraging a novel tensor network decomposition of quantum combs, the algorithm demonstrates efficiency even with a large number of channel uses (N=50). In the second part of the talk, I will explore the generalization of existing metrological upper bounds [Nat. Com. 3, 1063 (2012), PRL 131(9), 090801 (2023)] for correlated noise scenarios [arXiv:2410.01881].

Static patch holography is a conjectured duality between the static patch of an observer in de Sitter spacetime and a quantum theory defined on its (stretched) cosmological horizon. We illustrate from entanglement wedge reconstruction how a closed and connected de Sitter spacetime can emerge in this framework from the entanglement between the two holographic screens of two antipodal observers. In holographic spacetimes, a direct scattering in the bulk may not have a local boundary analog, imposing the existence of O(1/G) mutual information on the boundary. This statement is formalized by the connected wedge theorem, which is expected to hold beyond the AdS/CFT correspondence from which it originates. We consider scatterings in the static patch of an observer. We argue that for static patch holography to be consistent with the connected wedge theorem, causality on the stretched horizon should be induced from null infinity. In particular, signals propagating in the static patch are associated with fictitious local operators at null infinity. We present a sketch of proof of the connected wedge theorem in asymptotically de Sitter spacetime using induced causality.