45 research outputs found
Transverse-mode coupling and diffraction loss in tunable Fabry-Pé rot microcavities
Wereport on measurements and modeling of the mode structure of tunable Fabry–Pérot optical microcavities with imperfect mirrors.Wefind that non-spherical mirror shape and finite mirror size leave the fundamental mode mostly unaffected, but lead to loss, mode deformation, and shifted resonance frequencies at particular mirror separations. For small mirror diameters, the useful cavity length is limited to values significantly below the expected stability range.Weexplain the observations by resonant coupling between different transverse modes of the cavity and mode-dependent diffraction loss. A model based on resonant state expansion that takes into account the measured mirror profile can reproduce the measurements and identify the parameter regime where detrimental effects of mode mixing are avoided
Experimental GHZ Entanglement beyond Qubits
The Greenberger-Horne-Zeilinger (GHZ) argument provides an all-or-nothing
contradiction between quantum mechanics and local-realistic theories. In its
original formulation, GHZ investigated three and four particles entangled in
two dimensions only. Very recently, higher dimensional contradictions
especially in three dimensions and three particles have been discovered but it
has remained unclear how to produce such states. In this article we
experimentally show how to generate a three-dimensional GHZ state from
two-photon orbital-angular-momentum entanglement. The first suggestion for a
setup which generates three-dimensional GHZ entanglement from these entangled
pairs came from using the computer algorithm Melvin. The procedure employs
novel concepts significantly beyond the qubit case. Our experiment opens up the
possibility of a truly high-dimensional test of the GHZ-contradiction which,
interestingly, employs non-Hermitian operators.Comment: 6+6 pages, 8 figure
Interferon β-1a in relapsing multiple sclerosis: four-year extension of the European IFNβ-1a Dose-C omparison Study
Background: Multiple sclerosis (MS) is a chronic disease requiring long-term monitoring of treatment. Objective: To assess the four-year clinical efficacy of intramuscular (IM) IFNb-1a in patients with relapsing MS from the European IFNb-1a Dose-C omparison Study. Methods: Patients who completed 36 months of treatment (Part 1) of the European IFNb-1a Dose-C omparison Study were given the option to continue double-blind treatment with IFNb-1a 30 mcg or 60 mcg IM once weekly (Part 2). Analyses of 48-month data were performed on sustained disability progression, relapses, and neutralizing antibody (NA b) formation. Results: O f 608/802 subjects who completed 36 months of treatment, 493 subjects continued treatment and 446 completed 48 months of treatment and follow-up. IFNb-1a 30 mcg and 60 mcg IM once weekly were equally effective for up to 48 months. There were no significant differences between doses over 48 months on any of the clinical endpoints, including rate of disability progression, cumulative percentage of patients who progressed (48 and 43, respectively), and annual relapse rates; relapses tended to decrease over 48 months. The incidence of patients who were positive for NAbs at any time during the study was low in both treatment groups. Conclusion: C ompared with 60-mcg IM IFNb-1a once weekly, a dose of 30 mcg IM IFNb-1a once weekly maintains the same clinical efficacy over four years
Osteopontin deficiency protects against obesity-induced hepatic steatosis and attenuates glucose production in mice
Different approaches for interpretation and reporting of immunohistochemistry analysis results in the bone tissue – a review
Ultra-small mode volume cavities for the enhancement of Nitrogen-vacancy center fluorescence
Purcell-Enhanced Single-Photon Emission from Nitrogen-Vacancy Centers Coupled to a Tunable Microcavity
Optical microcavities are a powerful tool to enhance spontaneous emission of
individual quantum emitters. However, the broad emission spectra encountered in
the solid state at room temperature limit the influence of a cavity, and call
for ultra-small mode volume. We demonstrate Purcell-enhanced single photon
emission from nitrogen-vacancy (NV) centers in nanodiamonds coupled to a
tunable fiber-based microcavity with a mode volume down to .
We record cavity-enhanced fluorescence images and study several single emitters
with one cavity. The Purcell effect is evidenced by enhanced fluorescence
collection, as well as tunable fluorescence lifetime modification, and we infer
an effective Purcell factor of up to 2.0. With numerical simulations, we
furthermore show that a novel regime for light confinement can be achieved,
where a Fabry-Perot mode is combined with additional mode confinement by the
nanocrystal itself. In this regime, effective Purcell factors of up to 11 for
NV centers and 63 for silicon vacancy centers are feasible, holding promise for
bright single photon sources and efficient spin readout under ambient
conditions