The technologies of heating, photovoltaics, water photocatalysis and artificial photosynthesis depend on the absorption of light and novel approaches such as coherent absorption from a standing wave promise total dissipation of energy. Extending the control of absorption down to very low light levels and eventually to the single-photon regime is of great interest and yet remains largely unexplored. Here we demonstrate the coherent absorption of single photons in a deeply subwavelength 50% absorber. We show that while the absorption of photons from a travelling wave is probabilistic, standing wave absorption can be observed deterministically, with nearly unitary probability of coupling a photon into a mode of the material, for example, a localized plasmon when this is a metamaterial excited at the plasmon resonance. These results bring a better understanding of the coherent absorption process, which is of central importance for light harvesting, detection, sensing and photonic data processing applications.
Time-varying media have recently emerged as a new paradigm for wave manipulation, due to the synergy between the discovery of highly nonlinear materials, such as epsilon-near-zero materials, and the quest for wave applications, such as magnet-free nonreciprocity, multimode light shaping, and ultrafast switching. In this review, we provide a comprehensive discussion of the recent progress achieved with photonic metamaterials whose properties stem from their modulation in time. We review the basic concepts underpinning temporal switching and its relation with spatial scattering and deploy the resulting insight to review photonic time-crystals and their emergent research avenues, such as topological and non-Hermitian physics. We then extend our discussion to account for spatiotemporal modulation and its applications to nonreciprocity, synthetic motion, giant anisotropy, amplification, and many other effects. Finally, we conclude with a review of the most attractive experimental avenues recently demonstrated and provide a few perspectives on emerging trends for future implementations of time-modulation in photonics.
We present a method that allows determining the band-edge exciton fine structure of CdSe/CdS dot-in-rods samples based on single particle polarization measurements at room temperature. We model the measured emission polarization of such single particles considering the fine structure properties, the dielectric effect induced by the anisotropic shell, and the measurement configuration. We use this method to characterize the band-edge exciton fine structure splitting of various samples of dot-in-rods. We show that, when the diameter of the CdSe core increases, a transition from a spherical like band-edge exciton symmetry to a rod-like band edge exciton symmetry occurs. This explains the often reported large emission polarization of such particles compared to spherical CdSe/CdS emitters.
We address estimation of one-parameter qubit gates in the presence of phase diffusion. We evaluate the ultimate quantum limits to precision, seek optimal probes and measurements, and demonstrate an optimal estimation scheme for polarization encoded optical qubits. An adaptive method to achieve optimal estimation in any working regime is also analyzed in detail and experimentally implemented.
The FORWARD study is a randomised, double-blind trial that compares the efficacy and safety of 48 weeks treatment with extrafine beclomethasone dipropionate/formoterol fumarate (BDP/FOR), 100/6 μg pMDI, 2 inhalations BID, vs. FOR 12 μg pMDI, 1 inhalation BID, in severe COPD patients with a history of exacerbations. Co-primary endpoints were exacerbation rate over 48 weeks and pre-dose morning FEV(1) at 12 weeks. The ITT population included 1186 patients (69% males, mean age 64 years) with severe airflow limitation (mean post-bronchodilator FEV(1) 42% predicted). Salbutamol as rescue therapy, theophylline and tiotropium (if stable regimen prior to screening) were allowed. Compared to FOR, BDP/FOR: (1) reduced the exacerbation rate (rate ratio: 0.72 [95% confidence interval 0.62-0.84], p < 0.001); (2) improved pre-dose morning FEV(1) (mean difference: 0.069 L [0.043-0.095] p < 0.001); (3) prolonged the time to first exacerbation; (4) improved the SGRQ total score. The percentage of patients with adverse events was similar (52.1% with BDP/FOR and 49.2% with FOR). Pneumonia incidence was low, slightly higher with BDP/FOR (3.8%) than with FOR (1.8%). No difference for laboratory values, ECG or vital signs. Extrafine BDP/FOR significantly reduces the exacerbation rate and improves lung function of patients with severe COPD and history of exacerbations as compared to FOR alone.
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