@article{9334,
  abstract     = {Polaritons with directional in-plane propagation and ultralow losses in van der Waals (vdW) crystals promise unprecedented manipulation of light at the nanoscale. However, these polaritons present a crucial limitation: their directional propagation is intrinsically determined by the crystal structure of the host material, imposing forbidden directions of propagation. Here, we demonstrate that directional polaritons (in-plane hyperbolic phonon polaritons) in a vdW crystal (α-phase molybdenum trioxide) can be directed along forbidden directions by inducing an optical topological transition, which emerges when the slab is placed on a substrate with a given negative permittivity (4H–silicon carbide). By visualizing the transition in real space, we observe exotic polaritonic states between mutually orthogonal hyperbolic regimes, which unveil the topological origin of the transition: a gap opening in the dispersion. This work provides insights into optical topological transitions in vdW crystals, which introduce a route to direct light at the nanoscale.},
  author       = {Duan, J. and Álvarez-Pérez, G. and Voronin, K. V. and Prieto Gonzalez, Ivan and Taboada-Gutiérrez, J. and Volkov, V. S. and Martín-Sánchez, J. and Nikitin, A. Y. and Alonso-González, P.},
  issn         = {23752548},
  journal      = {Science Advances},
  number       = {14},
  publisher    = {AAAS},
  title        = {{Enabling propagation of anisotropic polaritons along forbidden directions via a topological transition}},
  doi          = {10.1126/sciadv.abf2690},
  volume       = {7},
  year         = {2021},
}

@article{10177,
  abstract     = {Phonon polaritons (PhPs)—light coupled to lattice vibrations—with in-plane hyperbolic dispersion exhibit ray-like propagation with large wave vectors and enhanced density of optical states along certain directions on a surface. As such, they have raised a surge of interest, promising unprecedented manipulation of infrared light at the nanoscale in a planar circuitry. Here, we demonstrate focusing of in-plane hyperbolic PhPs propagating along thin slabs of α-MoO3. To that end, we developed metallic nanoantennas of convex geometries for both efficient launching and focusing of the polaritons. The foci obtained exhibit enhanced near-field confinement and absorption compared to foci produced by in-plane isotropic PhPs. Foci sizes as small as λp/4.5 = λ0/50 were achieved (λp is the polariton wavelength and λ0 is the photon wavelength). Focusing of in-plane hyperbolic polaritons introduces a first and most basic building block developing planar polariton optics using in-plane anisotropic van der Waals materials.},
  author       = {Martín-Sánchez, Javier and Duan, Jiahua and Taboada-Gutiérrez, Javier and Álvarez-Pérez, Gonzalo and Voronin, Kirill V. and Prieto Gonzalez, Ivan and Ma, Weiliang and Bao, Qiaoliang and Volkov, Valentyn S. and Hillenbrand, Rainer and Nikitin, Alexey Y. and Alonso-González, Pablo},
  issn         = {23752548},
  journal      = {Science Advances},
  number       = {41},
  publisher    = {American Association for the Advancement of Science},
  title        = {{Focusing of in-plane hyperbolic polaritons in van der Waals crystals with tailored infrared nanoantennas}},
  doi          = {10.1126/sciadv.abj0127},
  volume       = {7},
  year         = {2021},
}

@article{7910,
  abstract     = {Quantum illumination uses entangled signal-idler photon pairs to boost the detection efficiency of low-reflectivity objects in environments with bright thermal noise. Its advantage is particularly evident at low signal powers, a promising feature for applications such as noninvasive biomedical scanning or low-power short-range radar. Here, we experimentally investigate the concept of quantum illumination at microwave frequencies. We generate entangled fields to illuminate a room-temperature object at a distance of 1 m in a free-space detection setup. We implement a digital phase-conjugate receiver based on linear quadrature measurements that outperforms a symmetric classical noise radar in the same conditions, despite the entanglement-breaking signal path. Starting from experimental data, we also simulate the case of perfect idler photon number detection, which results in a quantum advantage compared with the relative classical benchmark. Our results highlight the opportunities and challenges in the way toward a first room-temperature application of microwave quantum circuits.},
  author       = {Barzanjeh, Shabir and Pirandola, S. and Vitali, D and Fink, Johannes M},
  issn         = {23752548},
  journal      = {Science Advances},
  number       = {19},
  publisher    = {AAAS},
  title        = {{Microwave quantum illumination using a digital receiver}},
  doi          = {10.1126/sciadv.abb0451},
  volume       = {6},
  year         = {2020},
}

@article{6919,
  author       = {Qi, Chao and Minin, Giulio Di and Vercellino, Irene and Wutz, Anton and Korkhov, Volodymyr M.},
  issn         = {23752548},
  journal      = {Science Advances},
  number       = {9},
  publisher    = {American Association for the Advancement of Science},
  title        = {{Structural basis of sterol recognition by human hedgehog receptor PTCH1}},
  doi          = {10.1126/sciadv.aaw6490},
  volume       = {5},
  year         = {2019},
}