Accelerated aging studies can be used to assess the degree of deterioration and predict the failure of specimens after exposure to known climatic conditions. In this paper, we investigate the freeze-thaw deterioration factor with X-ray computed microtomography (μCT) analysis to compare the deterioration due to freeze-thaw cycles for cement mortar samples with and without 5
Entanglement swapping is a protocol that details how to create entanglement between previously uncorrelated particles. Its photonic version, mediated by the interference of photon pairs generated by separate quantum systems, finds disparate applications in quantum networks. So far, entanglement swapping with entangled photons from remote systems has been implemented only using probabilistic sources. However, the scaling up of quantum networks requires nonprobabilistic quantum emitters without a trade-off between the degree of entanglement and photon-pair generation rate. Here, we demonstrate photonic entanglement swapping using photon pairs generated by two separate GaAs quantum dots. The emitters are deterministically embedded in hybrid semiconductor-piezoelectric devices that make the entangled photons from two dissimilar quantum dots nearly identical. Entanglement swapping is demonstrated with a fidelity as high as 0.71(2), more than 10 SDs above the classical limit. The experimental data are quantitatively explained by a theoretical model that also suggests how to boost the protocol performance. Our work opens the path to the exploitation of quantum dot entangled-photon sources in quantum repeater networks.
Polariton interferometry through optical near-field microscopy has become a powerful tool in nanophotonics, enabling direct spatial access to the propagation characteristics of strongly confined, evanescent polariton modes. Scattering-type near-field optical microscopy has matured as the prime tool for such studies, yet mostly the out-of-plane components of the optical near fields are probed, owing to the elongated geometry of the nanotip. Here, we demonstrate a complementary far-field nonlinear microscopy approach that allows selective probing of in-plane polariton field components. Accessing the full vector field is interesting when studying complex mode patterns such as hyperbolic polaritons or skyrmions, where the in-plane field components are typically only inferred from the out-of-plane component but not measured directly. To this end, we use nonlinear infrared-visible wide-field sum-frequency generation microscopy, where the short visible wavelength of the nonlinear signal provides the high spatial resolution to access evanescent modes in the infrared. The symmetry selection rules of the nonlinear process further enable polarization-selective imaging of both in-plane polariton field components through spatial interferometry. The concept is demonstrated experimentally using surface phonon polaritons at the AlN-air interface launched by a gold antenna. A simple, semi-analytical model reproduces the peculiar propagation patterns. Hyperspectral imaging with a tunable narrowband laser further gives access to the polariton dispersion. The wide-field methodology holds high promise for in-depth and high-throughput studies of infrared nanophotonic structures.
Three state-of-the-art adaptive population control strategies (PCS) are theoretically and empirically investigated for a multirecombinative, cumulative step-size adaptation Evolution Strategy (mu/mu(I), lambda)-CSA-ES. First, scaling properties for the generation number and mutation strength rescaling are derived on the sphere in the limit of large population sizes. Then, the adaptation properties of three standard CSA variants are studied for varying population size and dimensionality, and compared to the predicted scaling results. Thereafter, three PCS are implemented along the CSA-ES and studied on a test bed of sphere, random, and Rastrigin functions. The CSA properties significantly influence the performance and stability of PCS, which is shown in greater detail. Given the test bed, well-performing parameter sets (in terms of scaling, efficiency, and success rate) for both the CSA- and PCS-subroutines are identified.
