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A bstract We implement a bootstrap method that combines stationary state conditions, thermal inequalities, and semidefinite relaxations of matrix logarithm in the ungauged one-matrix quantum mechanics, at finite rank N as well as in the large N limit, and determine finite temperature observables that interpolate between available analytic results in the low and high temperature limits respectively. We also obtain bootstrap bounds on thermal phase transition as well as preliminary results in the ungauged two-matrix quantum mechanics.

We establish an equivalence between non-isometry of quantum codes and state dependence of operator reconstruction, and discuss implications of this equivalence for holographic duality. Specifically, we define quantitative measures of non-isometry and state dependence and describe bounds relating these quantities. In the context of holography we show that, assuming known gravitational path integral results for overlaps between semiclassical states, non-isometric bulk-to-boundary maps with a trivial kernel are approximately isometric and bulk reconstruction approximately state-independent. In contrast, non-isometric maps with a non-empty kernel always lead to state-dependent reconstruction. We also show that if a global bulk-to-boundary map is non-isometric, then there exists a region in the bulk which is causally disconnected from the boundary. Finally, we conjecture that, under certain physical assumptions for the definition of the Hilbert space of effective field theory in AdS space, the presence of a global horizon implies a non-isometric global bulk-to-boundary map.

The entanglement negativity $\\mathcal{E}$(A : B) is a useful measure of quantum entanglement in bipartite mixed states. In random tensor networks (RTNs), which are related to fixed-area states, it was found in ref. [1] that the dominant saddles computing the even Rényi negativity $\\mathcal{E}$(2k) generically break the ℤ2k replica symmetry. This calls into question previous calculations of holographic negativity using 2D CFT techniques that assumed ℤ2k replica symmetry and proposed that the negativity was related to the entanglement wedge cross section. In this paper, we resolve this issue by showing that in general holographic states, the saddles computing $\\mathcal{E}$(2k) indeed break the ℤ2k replica symmetry.

The electric monopole (\\(E0\\)) transition strength \\(\\rho^2\\) for the transition connecting the third 0\\(^+\\) level, a \"superdeformed\" band head, to the \"spherical\" 0\\(^+\\) ground state in doubly magic \\(^{40}\\)Ca has been determined via \\(e^+e^-\\) pair-conversion spectroscopy. The measured value, \\(\\rho^2(E0; 0^+_3 \\to 0^+_1)~=~2.3(5)\\times10^{-3}\\), is the smallest \\(\\rho^2(E0; 0^+ \\to 0^+)\\) found in \\(A<50\\) nuclei. In contrast, the \\(E0\\) transition strength to the ground state observed from the second 0\\(^+\\) state, a band head of \"normal\" deformation, is an order of magnitude larger, \\(\\rho^2(E0; 0^+_2 \\to 0^+_1)~=~25.9(16)\\times~10^{-3}\\), which shows significant mixing between these two states. Large-Scale Shell Model (LSSM) calculations were performed to understand the microscopic structure of the excited states, and the configuration mixing between them; experimental \\(\\rho^2\\) values in \\(^{40}\\)Ca and neighboring isotopes were well reproduced by the LSSM calculations. The unusually small \\(\\rho^2(E0; 0^+_3 \\to 0^+_1)\\) value is due to destructive interference in the mixing of shape-coexisting structures, which are based on several different multiparticle-multihole excitations. This observation goes beyond the usual treatment of \\(E0\\) strengths, where two-state shape mixing cannot result in destructive interference.

The concept of Berry curvature is essential for various transport phenomena. However, an effect of the Berry curvature on magnetochiral anisotropy, i.e. nonreciprocal magneto-transport, is still elusive. Here, we report the Berry curvature originates the large magnetochiral anisotropy. In Weyl-semimetal WTe2, we observed the strong enhancement of the magnetochiral anisotropy when the Fermi level is located near the Weyl points. Notably, the maximal figure of merit \\(\\bar{\\gamma}\\) reaches \\(1.2\\,{\\times}10^{-6} \\rm{m^2T^{-1}A^{-1}}\\), which is the largest ever reported in bulk materials. Our semiclassical calculation shows that the diverging Berry curvature at the Weyl points strongly enhances the magnetochiral anisotropy.

A bstract The Quantum Focusing Conjecture (QFC) lies at the foundation of holography and semiclassical gravity. The QFC implies the Bousso bound and the Quantum Null Energy Condition (QNEC). The QFC also ensures the consistency of the quantum extremal surface prescription and bulk reconstruction in AdS/CFT. However, the central object in the QFC — the expansion of lightrays — is not defined at points where geodesics enter or leave a null congruence. Moreover, the expansion admits three inequivalent quantum extensions in terms of the conditional max, min, and von Neumann entropies. Here we formulate a discrete notion of nonexpansion that can be evaluated even at nonsmooth points. Moreover, we show that a single conjecture, the discrete max -QFC, suffices for deriving the QNEC, the Bousso bound, and key properties of both max and min entanglement wedges. Continuous numerical values need not be assigned, nor are the von Neumann or min-versions of the quantum expansion needed. Both our new notion of nonexpansion, and also the properties of conditional max entropies, are inherently asymmetric and outward directed from the input wedge. Thus the framework we develop here reduces and clarifies the axiomatic structure of semiclassical gravity, eliminating redundancies and fixing ambiguities. We also derive a new result: the strong subadditivity of the generalized smooth conditional max and min entropies of entanglement wedges.

A bstract The simple or “outermost” wedge in AdS is the portion of the entanglement wedge that can be reconstructed with sub-exponential effort from CFT data. Here we furnish a definition in arbitrary spacetimes: given an input wedge a analogous to a CFT boundary region, the simple wedge z ( a ) is the largest wedge accessible by a “zigzag,” a certain sequence of antinormal lightsheets. We show that z ( a ) is a throat, and that it is contained in every other throat. This implies that z ( a ) is unique; that it is contained in the generalized entanglement wedge; and that it reduces to the AdS prescription as a special case. The zigzag explicitly constructs a preferred Cauchy slice that renders the simple wedge accessible from a ; thus it adds a novel structure even in AdS. So far, no spacelike construction is known to reproduce these results, even in time-symmetric settings. This may have implications for the modeling of holographic encoding by tensor networks.

A bstract A search is performed for long-lived heavy neutral leptons (HNLs), produced through the decay of a W boson along with a muon or electron. Two channels are explored: a leptonic channel, in which the HNL decays into two leptons and a neutrino, and a semi-leptonic channel, in which the HNL decays into a lepton and a charged pion. The search is performed with 140 fb − 1 of s = 13 TeV proton-proton collision data collected by ATLAS during Run 2 of the Large Hadron Collider. No excess of events is observed; Dirac-like and Majorana-like HNLs with masses below 14.5 GeV and mixing coefficients as small as 10 − 7 are excluded at the 95% confidence level. The results are interpreted under different assumptions on the flavour of the leptons from the HNL decays.