Robust Measurements of n-Point Correlation Functions of Driven-Dissipative Quantum Systems on a Digital Quantum Computer.

We propose and demonstrate a unified hierarchical method to measure n-point correlation functions that can be applied to driven, dissipative, or otherwise open or nonequilibrium quantum systems. In this method, the time evolution of the system is repeatedly interrupted by interacting an ancilla qubit with the system through a controlled operation, and measuring the ancilla immediately afterward. We discuss the robustness of this method as compared to other ancilla-based interferometric techniques (such as the Hadamard test), and highlight its advantages for near-term quantum simulations of open quantum systems.

Impact of SARS-CoV2 infection on mortality and hospitalization in nursing home residents during the "Omicron era".

Background: Widespread vaccination and emergence of less aggressive SARS-CoV2 variants may have blunted the unfavourable outcomes of COVID-19 in nursing home (NH) residents. We analysed the course of COVID-19 epidemic in NHs of Florence, Italy, during the "Omicron era" and investigated the independent effect of SARS-CoV2 infection on death and hospitalization risk.

Methods: Weekly SARS-CoV2 infection rates between November 2021 and March 2022 were calculated.

Mechanism of superconductivity in the Hubbard model at intermediate interaction strength.

We study the fluctuations responsible for pairing in the -wave superconducting state of the two-dimensional Hubbard model at intermediate coupling within a cluster dynamical mean-field theory with a numerically exact quantum impurity solver. By analyzing how momentum- and frequency-dependent fluctuations generate the -wave superconducting state in different representations, we identify antiferromagnetic fluctuations as the pairing glue of superconductivity in both the underdoped and the overdoped regime. Nevertheless, in the intermediate coupling regime, the predominant magnetic fluctuations may differ significantly from those described by conventional spin fluctuation theory.

Alzheimer's Disease CSF Biomarker Profiles in Idiopathic Normal Pressure Hydrocephalus.

Patients with idiopathic normal pressure hydrocephalus (iNPH) frequently show pathologic CSF Aβ levels, comparable with Alzheimer's Disease (AD). Nevertheless, the clinical meaning of these findings has not been fully explained. We aimed to assess the role of AD CSF biomarkers (Aβ, Aβ/Aβ, p-tau, t-tau) in iNPH.

Photonic polarization gears for ultra-sensitive angular measurements.

Quantum metrology bears a great promise in enhancing measurement precision, but is unlikely to become practical in the near future. Its concepts can nevertheless inspire classical or hybrid methods of immediate value. Here we demonstrate NOON-like photonic states of m quanta of angular momentum up to m=100, in a setup that acts as a 'photonic gear', converting, for each photon, a mechanical rotation of an angle θ into an amplified rotation of the optical polarization by mθ, corresponding to a 'super-resolving' Malus' law.