Generation of a time-bin Greenberger--Horne--Zeilinger state with an optical switch

Multipartite entanglement is a critical resource in quantum information processing that exhibits much richer phenomenon and stronger correlations than in bipartite systems. This advantage is also reflected in its multi-user applications. Although many demonstrations have used photonic polarization qubits, polarization-mode dispersion confines the transmission of photonic polarization qubits through an optical fiber. Consequently, time-bin qubits have a particularly important role to play in quantum communication systems. Here, we generate a three-photon time-bin Greenberger-Horne-Zeilinger (GHZ) state using a 2 x 2 optical switch as a time-dependent beam splitter to entangle time-bin Bell states from a spontaneous parametric down-conversion source and a weak coherent pulse. To characterize the three-photon time-bin GHZ state, we performed measurement estimation, showed a violation of the Mermin inequality, and used quantum state tomography to fully reconstruct a density matrix, which shows a state fidelity exceeding 70%. We expect that our three-photon time-bin GHZ state can be used for long-distance multi-user quantum communication.Comment: 8 pages, 4 figures, 1 tabl

Mechanical Characterization of Rabbit Pulmonary Vein Sleeves in In Vitro Intact Ring Preparation

BackgroundPulmonary vein (PV) sleeves, composed of cardiomyocytes, play certain roles in arrhythmogenesis. In the literature, it has been frequently reported that PV sleeves possess intrinsic spontaneous pacemaking activity and triggered activity in normal dogs and rabbits. In contrast, other research groups presented totally opposite findings which showed absence of such pacemakers in dogs, rabbits and rats. The present study was designed to clarify this puzzle and contradiction.MethodsA novel methodology using in vitro experimentation was used to examine the electromechanical activity of whole segments of PV sleeves. The ring preparation was composed of a small piece of left atrial (LA) free wall, PV ostium and sleeve from rabbits. A circumferential contraction of the PV sleeve was measured when the preparation was electrically driven from the LA free wall. Mechanical force of the ring preparation was measured using a force transducer. The action potentials were recorded using conventional intracellular recording technique in strip preparation.ResultsIn 15 rabbits, no spontaneous pacemaking activity or triggered activity was found in the in vitro ring preparation of PV sleeve. The circumferential contraction of PV sleeves was external calcium-dependent. Frequency-force relation displayed a negative staircase at 0.1–0.5 Hz and a positive staircase at 1–5 Hz. Post-rest potentiation was prominent between 15 s and 120 s. Intracellular action potential recording did not display any automaticity or triggered activity in PV sleeves.ConclusionIn an intact ring preparation of rabbit PV sleeves, intrinsic spontaneous pacemaking activity or triggered activity was not found

Incorporation of atomic Fe-oxide triggers a quantum leap in the CO2 methanation performance of Ni-hydroxide

The heterogeneous catalytic conversion of carbon dioxide (CO2) to methane (CH4) via CO2 methanation offers a promising avenue for establishing the closed carbon loop. Nevertheless, the lack of effective catalysts limits its industrial applications. Considering this, we developed a novel heterogeneous catalyst comprising oxygen vacancies enriched atomic Fe-oxide clusters confined in the TiO2-supported Ni-hydroxide (denoted as NiFe-TiO2) via wet chemical reduction method. This material delivers an unprecedently high CH4 productivity of ∼24,358 mmol g-1h−1 in CO2 methanation at 300 °C, surpassing the Ni-TiO2 (12,481 mmol g-1h−1) by ∼ 95 %. On top of that, the high structural reliability of the Fe-oxide atomic clusters endows the NiFe-TiO2 catalyst with outstanding durability, where it achieves an optimum CH4 productivity of ∼ 36,399 mmol g-1h−1 after 116 cycles (155 h) with CH4 selectivity of 90.5 % and retains the pristine performance up to 220 cycles (330 h) in the stability test. With evidence from in-situ X-ray absorption and ambient pressure X-ray photoelectron spectroscopy studies, the performance descriptors and reaction pathways were unveiled, where the oxygen vacancies in the atomic Fe-oxide clusters and the adjacent Ni-hydroxide domains synergistically boost the CO2 activation and the H2 dissociation, respectively. Such a potential synergy enables the simultaneous operation of all intermediate steps for enhanced CO2 methanation kinetics on the NiFe-TiO2 surface. Most importantly, these findings not only unravel the merits of oxygen vacancies in transition metals for CO2 methanation but mark a step ahead for the rational design of heterogeneous catalysts in various catalytic applications

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio