We present high-resolution two-color photoassociation spectroscopy of Bose-Einstein condensates of ytterbium atoms. The use of narrow Raman resonances and careful examination of systematic shifts enabled us to measure 13 bound state energies for three isotopologues of the ground state ytterbium molecule with standard uncertainties on the order of 500 Hz. The atomic interactions are modeled using an ab initio based mass scaled Born-Oppenheimer potential whose long range van der Waals parameters and total WKB phase are fitted to experimental data. We find that the quality of the fit of this model, of about 112.9 kHz (RMS) can be significantly improved by adding the recently calculated beyond-Born-Oppenheimer (BBO) adiabatic corrections [

The refractive index sensitivity of a localized surface plasmon resonance (LSPR) sensor is correlated to an enhanced local electromagnetic (EM) field originating from noble metal nanostructures. Here, we demonstrated that extensive EM field enhancement by a gold (Au) nanocone array (AuNCA) allowed highly sensitive and label-free detection of biomolecules in the visible wavelength spectrum. The AuNCA consisted of a polymer core and an Au shell, which was fabricated by using simple and inexpensive nanoimprint lithography. Under LSPR excitation, AuNCA absorbs visible light of a specific wavelength and extensively enhances the EM field near its surface. It was shown that AuNCA had high refractive index sensitivity (417.5 nm/RIU) because of the large distribution of the enhanced EM field, covering a large surface of the NCA. Moreover, in DNA hybridization detection, a very low limit of detection of 161 fM was achieved, and 1-base mismatch DNA was successfully discriminated by using AuNCA.

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Several extensions to the Standard Model of particle physics, including light dark matter candidates and unification theories predict deviations from Newton’s law of gravitation. For macroscopic distances, the inverse-square law of gravitation is well confirmed by astrophysical observations and laboratory experiments. At micrometer and shorter length scales, however, even the state-of-the-art constraints on deviations from gravitational interaction, whether provided by neutron scattering or precise measurements of forces between macroscopic bodies, are currently many orders of magnitude larger than gravity itself. Here we show that precision spectroscopy of weakly bound molecules can be used to constrain non-Newtonian interactions between atoms. A proof-of-principle demonstration using recent data from photoassociation spectroscopy of weakly bound Yb2 molecules yields constraints on these new interactions that are already close to state-of-the-art neutron scattering experiments. At the same time, with the development of the recently proposed optical molecular clocks, the neutron scattering constraints could be surpassed by at least two orders of magnitude.

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