The light-matter quantum interface that can create quantum correlations or entanglement between a photon and one atomic collective excitation is a fundamental building block for a quantum repeater. The intrinsic limit is that the probability of preparing such nonclassical atom-photon correlations has to be kept low in order to suppress multiexcitation. To enhance this probability without introducing multiexcitation errors, a promising scheme is to apply multimode memories to the interface. Significant progress has been made in temporal, spectral, and spatial multiplexing memories, but the enhanced probability for generating the entangled atom-photon pair has not been experimentally realized. Here, by using six spin-wave-photon entanglement sources, a switching network, and feedforward control, we build a multiplexed light-matter interface and then demonstrate a ∼sixfold (∼fourfold) probability increase in generating entangled atom-photon (photon-photon) pairs. The measured compositive Bell parameter for the multiplexed interface is 2.49±0.03 combined with a memory lifetime of up to ∼51  μs.

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The generation and storage of entangled photons play important roles in quantum information technique. Spontaneous Raman scattering (SRS) in atomic ensembles provides a promising method to generate entangled photons capable of storage. In the past experiments, a spin-wave-photon entangled state is produced via SRS in an atomic ensemble, with which a pair of entangled photons is obtained. Here, we report a scheme of simultaneously generating two spin-wave-photon entangled states in an atomic ensemble by collecting Stokes photons at two different directions. Based on the obtained two atom-photon entangled sources, we generate a three-photon GHZ polarization-entangled state and conditionally prepare a polarization-entangled photon pair, respectively. 2The entangled photon pairs are the crucial resources in linear optical quantum computations (LOQC) and quantum communications (QC) [1][2][3][4][5].However, the probabilistic generations of entangled photons limit their applications in the real world [1,[6][7]. For solving this problem, a promising scheme is to effectively store the entangled photons in atomic or solid-state ensembles for a desired time [1][2][3][4][5].Spontaneous Raman scattering (SRS) in an atomic ensemble can emit a single photon and simultaneously create a single spin-wave excitation [8][9][10][11][12][13][14][15][16][17][18][19][20].The emitted photon can be directly stored in atomic ensembles via EIT with a larger storage efficiency up to 20-50% [11][12][13]. The correlation between the emitted photons and the spin-wave excitations forms the physical fundament of generating the spin-wave-photon (atom-photon) entanglement [3]. In past experiments [13][14][15][16][17], an atom-photon entangled state has been generated from a cold atomic ensemble, with which a pair of entangled photons is obtained.However, in some quantum information protocols, the three-qubit GHZ state[18] and on-demand entanglement source [19] are required, whose preparation relies on the simultaneous generations of two or more entangled photon pairs capable of storages.On the other hand, although the quantum repeater node [17] has been experimentally demonstrated by using two atom-photon entangled states simultaneously generated from two cold atomic ensembles, the storage 2 3 3 lifetime of the entanglement is very short (~ 6 µs), which is not enough for the long-distance quantum communication [17]. For solving this problem, we can firstly produce a pair of polarization-entangled photons in a heralded or conditional manner, and then mapped the entanglement into atomic-ensemble memories via the long-lived (1-ms) EIT quantum storage scheme [20].In this letter, we present an experimental demonstration of the simultaneous generation of two atom-photon entangled states in a cold atomic ensemble via SRS induced by a write laser pulse. In contrast to past experiments [13,[16][17], which achieved the high-fidelity atom-photon entanglement by encoding the photonic qubit in two spatial modes of a single photon, the presented experiment empl...

Due to the axial curvature and the eccentric vehicle loads, bending-torsion couple effects will be generated in the curved steel-concrete composite box beam bridges. To study the bending-torsion couple characteristics, six steel-concrete composite box model beams are tested under the bending-torsion couple loads, with the initial torsion-bending ratios and shear connection degrees as the design parameters. The ultimate bearing capacity, section strain, and interfacial slip of the steel-concrete composite box beams are measured. The test results show that, the fully connected composite beams mainly express bending or bending-torsion failure modes, but the partially connected composite beams are mainly sliding failure modes. The existence of the torque doesn’t have great influence on the ultimate bearing capacity and bending moment of the composite box beams. Under the bending-torsion couple loads, there are not only the longitudinal slip between the steel girder and concrete slab of the composite box beam, but also the transverse slip perpendicular to the beam axis.