Electro-Optical Sampling of Single-Cycle THz Fields with Single-Photon Detectors.

Electro-optical sampling of Terahertz fields with ultrashort pulsed probes is a well-established approach for directly measuring the electric field of THz radiation. This technique usually relies on balanced detection to record the optical phase shift brought by THz-induced birefringence. The sensitivity of electro-optical sampling is, therefore, limited by the shot noise of the probe pulse, and improvements could be achieved using quantum metrology approaches using, e.g., NOON states for Heisenberg-limited phase estimation. We report on our experiments on THz electro-optical sampling using single-photon detectors and a weak squeezed vacuum field as the optical probe. Our approach achieves field sensitivity limited by the probe state statistical properties using phase-locked single-photon detectors and paves the way for further studies targeting quantum-enhanced THz sensing.

Topological beaming of light.

Nanophotonic light emitters are key components in numerous application areas because of their compactness and versatility. Here, we propose a topological beam emitter structure that takes advantage of submicrometer footprint size, small divergence angle, high efficiency, and adaptable beam shaping capability. The proposed structure consists of a topological junction of two guided-mode resonance gratings inducing a leaky Jackiw-Rebbi state resonance. The leaky Jackiw-Rebbi state leads to in-plane optical confinement with funnel-like energy flow and enhanced emission probability, resulting in highly efficient optical beam emission. In addition, the structure allows adaptable beam shaping for any desired positive definite profiles by means of Dirac mass distribution control, which can be directly encoded in lattice geometry parameters. Therefore, the proposed approach provides highly desirable properties for efficient micro-light emitters and detectors in various applications including display, solid-state light detection and ranging, laser machining, label-free sensors, optical interconnects, and telecommunications.

Quantum plasmonic sensing using single photons.

Reducing the noise below the shot-noise limit in sensing devices is one of the key promises of quantum technologies. Here, we study quantum plasmonic sensing based on an attenuated total reflection configuration with single photons as input. Our sensor is the Kretschmann configuration with a gold film, and a blood protein in an aqueous solution with different concentrations serves as an analyte. The estimation of the refractive index is performed using heralded single photons. We also determine the estimation error from a statistical analysis over a number of repetitions of identical and independent experiments. We show that the errors of our plasmonic sensor with single photons are below the shot-noise limit even in the presence of various experimental imperfections. Our results demonstrate a practical application of quantum plasmonic sensing is possible given certain improvements are made to the setup investigated, and pave the way for a future generation of quantum plasmonic applications based on similar techniques.

Association between perceived stress, alcohol consumption levels and obesity in Koreans.

BACKGROUND AND OBJECTIVES: Coping with stress often leads to unhealthy behaviors that can have an impact on the development of obesity. Therefore, this study is investigate the effect of perceived stress level on alcohol consumption habits, as well as the effect of the interaction between alcohol consumption habits and stress level on obesity in Koreans. METHODS AND STUDY DESIGN: We analyzed perceived stress, alcohol consumption habits (alcohol consumption status, quantity, and alcohol use disorders identification test) and the anthropometrics of 6,229 subjects from the Korean National Health and Nutrition Examination Survey. The gender-based differences of the effect of the perceived level of stress on alcohol consumption habits and anthropometric measurements, as well as the interaction of the perceived level of stress and alcohol consumption habits on prevalence or ORs of obesity were analyzed. RESULTS: The subjects with high perceived stress showed higher proportions for unhealthy alcohol consumption habits than those with low perceived stress [ORs (95% CIs)=1.35 (1.19-1.54), 1.95 (1.68-2.26), and 1.87 (1.60-2.19) for alcohol consumption status, alcohol consumption quantity, and alcohol use disorders identification test, respectively]. Men showed significant interactions between the perceived stress and all alcohol consumption habits with respect to obesity [ORs (95% CIs)=1.28 (1.06-1.55), 1.81 (1.52-2.16), and 1.40 (1.17-1.68) for alcohol consumption status, alcohol consumption quantity, and alcohol use disorders identification test, respectively]. Among women, interactions between the perceived stress and alcohol consumption status [ORs (95% CIs)=0.70 (0.60-0.83)] and alcohol consumption quantity [ORs (95% CIs)=0.93 (0.54-1.36)] in relation to obesity were found to be significant. CONCLUSION: Our study demonstrated that the perceived stress influenced alcohol consumption habits that may have impacted obesity.