We investigate quantum characteristics around Schwarzschild black hole, exploring various quantum resources and their interplay in curved space-time. Our analysis reveals intriguing behaviors of quantum coherence, global and genuine multipartite entanglement, first-order coherence, and mutual information in different scenarios. Initially, we consider three particles shared among Alice, Bob, and Charlie in a Minkowski space far from the event horizon, where these particles are correlated via Greenberger-Horne-Zeilinger-type correlation. While Alice’s particle remains in Minkowski space, Bob and Charlie accelerate towards the event horizon, experiencing black hole evaporation and generating antiparticles correlated via the Hawking effect. We employ the Kruskal basis formulation to derive a pentapartite pure state shared among particles inside and outside the event horizon. Investigating different scenarios among particles both inside and outside the event horizon, we observe how quantum resources evolve and distribute among consideration of different particles with Hawking temperature and mode frequency. The trade-off relationship between first-order coherence and concurrence fill persists, indicating the intricate interplay between coherence and entanglement. Notably, the mutual information between external observers and particles inside the black hole becomes nonzero, deepening our understanding of quantum effects in curved space-time and shedding light on the quantum nature of the black hole. We believe that these findings will pave the way for future investigations into the fundamental quantum mechanical aspects of gravity under extreme environments.

The measurement precision for two incompatible observables in a typical quantum system can be improved by the aid of one particle as a quantum memory. In this work, we study the entropic uncertainty relation in the presence of quantum memory (EUR-QM) and dense coding capacity (DCC) for arbitrary two-qubit X-states, and then we obtain an explicit relationship between the lower bound of the uncertainty and DCC. As an example, we examine the thermal EUR-QM as well as DCC in two kinds of two-qubit spin squeezing models (one-axis twisting model and two-axis counter-twisting model) under an external magnetic field. In the following, we relate EUR-QM to DCC and show analytically that there is an anti-correlated relation between them, and especially in the ground state. Our results show that for both the models, the entropic uncertainty and its bound can be decreased by reinforcing the spin squeezing parameters or decreasing the temperature of the system. Notably, we reveal that the valid dense coding cannot carry out in the one-axis twisting model, nevertheless, if we properly choose the Hamiltonian parameters, the two-axis counter-twisting model not only carries out the valid dense coding but also the optimal dense coding surely can be achieved. Thereby, our observations might offer new insights into quantum measurement precision and the optimal dense coding for the regimes of various solid-state systems.

In this paper, we examine the sensitivity of the three top quark production at the LHC to the top quark flavor-changing neutral currents (FCNC) as well as the sensitivity of the four top production to the strong and weak dipole moments of the top quark. Upper limits at 95% CL on the branching fractions of $\mathcal{B}(t\to qX)$, where $X=g$, $Z$, $\gamma$, $H$ and $q=u$, $c$, are set by performing an analysis on three top events in the same-sign dilepton channel. We consider the main sources of the background processes and a realistic detector simulation is performed at the center-of-mass energy of 14 TeV. In the second part of this work, based on the recent upper limits which have been set on the four top quark cross section by the ATLAS and CMS collaborations from 13 TeV data, we constrain the top quark strong and weak dipole moments. The bounds on the top quark dipole moments are presented using the future LHC prospects for four top quark cross section measurement.

Recently a new class of asymptotically AdS ultra-spinning black holes has been constructed with a noncompact horizon of finite area [R. A. Hennigar, D. Kubiznak, and R. B. Mann, Super-Entropic Black Holes, Phys. Rev. Lett. 115, 031101 (2015).], in which the asymptotic rotation is effectively boosted to the speed of light. We employ this technique for four-dimensional $U(1{)}^4$ and five-dimensional $U(1{)}^3$ gauged supergravity black holes. The obtained new exact black hole solutions for both cases possess a noncompact horizon; their topologies are a sphere with two punctures. We then demonstrate that the ultra-spinning limit commutes with the extremality condition as well as the near horizon limit for both black holes. We also show that the near horizon extremal geometries of the resulting ultra-spinning gauged supergravity black holes lead to the well-known result which contains an ${\mathrm{AdS}}_2$ throat. We then obtain the $[(d-1)/2]$ central charges of the dual CFTs. By assuming the Cardy formula, we show that despite the noncompactness of the horizon, microscopic entropy of the dual CFT is precisely equivalent to the Bekenstein-Hawking entropy.

The effects of classical correlations and associated decoherence on the fidelity dynamics of two qubits initially prepared in maximally entangled (ME) and coherent states are examined. In both the Markovian and non-Markovian regimes, the dynamics of fidelity in a correlated dephasing channel is probed. We show that fidelity decreases over time but does not disappear completely, implying that the output state does not become quite dissimilar from the input state under the effects of dephasing correlated channel. The ME state, in comparison, is more tolerant of the dephasing effects of the correlated channel than that of the maximally coherent state. Fidelity of the quantum states is significantly influenced by the degree of classical correlations between successive actions of the channel on the two qubits. As the amount of classical correlations in the implementation of the channel increases, the fidelity of the quantum states can be noticeably enhanced.