High-extinction-ratio resonant cavity polarizer for quantum-optics measurements

The use of a high-finesse Fabry-Perot ring cavity with an odd number of reflections as a high-extinction-ratio resonant polarizer is shown. Experimental results from quantum-noise measurements using resonant cavities as spatial and spectral filters and precision polarizers are presented

Transverse and longitudinal characterization of electron beams using interaction with optical near-fields

We demonstrate an experimental technique for both transverse and longitudinal characterization of bunched femtosecond free electron beams. The operation principle is based on monitoring of the current of electrons that obtained an energy gain during the interaction with the synchronized optical near-field wave excited by femtosecond laser pulses. The synchronous accelerating/decelerating fields confined to the surface of a silicon nanostructure are characterized using a highly focused sub-relativistic electron beam. Here the transverse spatial resolution of 450 nm and femtosecond temporal resolution achievable by this technique are demonstrated

Efficient half-harmonic generation of three-optical-cycle mid-IR frequency comb around 4 µm using OP-GaP

We report a broadband mid-infrared frequency comb with three-optical-cycle pulse duration centered around 4.2 µm, via half-harmonic generation using orientation-patterned GaP (OP-GaP) with ~43% conversion efficiency. We experimentally compare performance of GaP with GaAs and lithium niobate as the nonlinear element, and show how properties of GaP at this wavelength lead to generation of the shortest pulses and the highest conversion efficiency. These results shed new light on half-harmonic generation of frequency combs, and pave the way for generation of short-pulse intrinsically-locked frequency combs at longer wavelengths in the mid-infrared with high conversion efficiencies

Octave-spanning ultrafast OPO with 2.6-6.1µm instantaneous bandwidth pumped by femtosecond Tm-fiber laser

We report the extension of broadband degenerate OPO operation further into mid-infrared. A femtosecond thulium fiber laser with output centered at 2050 nm synchronously pumps a 500-μm-long crystal of orientation patterned GaAs providing broadband gain centered at 4.1 µm. We observe a pump threshold of 17 mW and output bandwidth extending from 2.6 to 6.1 µm at the −30 dB level. Average output power was 37 mW. Appropriate resonator group dispersion is a key factor for achieving degenerate operation with instantaneously broad bandwidth. The output spectrum is very sensitive to absorption and dispersion introduced by molecular species inside the OPO cavity

Design of a Prostate Cancer Patient Navigation Intervention for a Veterans Affairs Hospital

Patient navigation programs have been launched nationwide in an attempt to reduce racial/ethnic and socio-demographic disparities in cancer care, but few have evaluated outcomes in the prostate cancer setting. The National Cancer Institute-funded Chicago Patient Navigation Research Program (C-PNRP) aims to implement and evaluate the efficacy of a patient navigation intervention for predominantly low-income minority patients with an abnormal prostate cancer screening test at a Veterans Affairs (VA) hospital in Chicago

Elastic response of [111]-tunneling impurities

We study the dynamic response of a [111] quantum impurity, such as lithium or cyanide in alkali halides, with respect to an external field coupling to the elastic quadrupole moment. Because of the particular level structure of a eight-state system on a cubic site, the elastic response function shows a biexponential relaxation feature and a van Vleck type contribution with a resonance frequency that is twice the tunnel frequency $\Delta/\hbar$. This basically differs from the dielectric response that does not show relaxation. Moreover, we show that the elastic response of a [111] impurity cannot be reduced to that of a two-level system. In the experimental part, we report on recent sound velocity and internal friction measurements on KCl doped with cyanide at various concentrations. At low doping (45 ppm) we find the dynamics of a single [111] impurity, whereas at higher concentrations (4700 ppm) the elastic response rather indicates strongly correlated defects. Our theoretical model provides a good description of the temperature dependence of $\delta v/v$ and $Q^{-1}$ at low doping, in particular the relaxation peaks, the absolute values of the amplitude, and the resonant contributions. From our fits we obtain the value of the elastic deformation potential $\gamma_t=0.192$ eV.Comment: 19 pages, 5 figure

Navigating Veterans with an Abnormal Prostate Cancer Screening Test: A Quasi-Experimental Study

Prostate cancer disproportionately affects low-income and minority men. This study evaluates the impact of a patient navigation intervention on timeliness of diagnostic resolution and treatment initiation among veterans with an abnormal prostate cancer screen.MethodsParticipants were enrolled between 2006 and 2010. The intervention involved a social worker and lay health worker navigation team that assisted patients in overcoming barriers to care. For navigated (n = 245) versus control (n = 245) participants, we evaluated rates of diagnostic resolution and treatment and adjusted for race, age, and Gleason score

A fully programmable 100-spin coherent Ising machine with all-to-all connections

Unconventional, special-purpose machines may aid in accelerating the solution of some of the hardest problems in computing, such as large-scale combinatorial optimizations, by exploiting different operating mechanisms than those of standard digital computers. We present a scalable optical processor with electronic feedback that can be realized at large scale with room-temperature technology. Our prototype machine is able to find exact solutions of, or sample good approximate solutions to, a variety of hard instances of Ising problems with up to 100 spins and 10,000 spin-spin connections