Ultracold quantum matter

Abstract:

Isotope shifts of all the stable isotopes and the hyperfine splittings of 115Sn, 117Sn and 119Sn have been measured in the transitions 5s25p23P0-5s 25p6s3P1 at 286 nm in Sn I. Tin atoms in a collimated beam to reduce the Doppler width were excited by radiation at 286 nm generated by frequency doubling the light from a CW ring dye laser. Spectra were recorded by monitoring the subsequent decay and calibrated by optical heterodyning. The relative positions of the isotopes are, in MHz: 112; 0.0(1.0), 114;319.5(1.3), 115;412.7(1.1), 116;640.0(0.6), 117;746.8(0.7), 118;945.2(0.7), 119;1039.3(1.1), 120;1214.4(0.5), 122;1448.5(0.7), 124;1656.0(0.7). The bracketed uncertainties are added in quadrature to give the errors of the isotope shifts. For odd-even shifts involving 112, 114, 120, 122 and 124 an extra 0.5 MHz must be added in quadrature. The hyperfine splitting factors of 5s25p6s3P1 are, in MHz: A(115)=-4395.4 (2.1), A(117)=-4790.71(1.7), A(119)=-5014.8(1.9). The results are interpreted in terms of the electronic and nuclear properties of the tin isotopes.

Abstract:

We outline the experimental concept and key scientific capabilities of AION (Atom Interferometer Observatory and Network), a proposed UK-based experimental programme using cold strontium atoms to search for ultra-light dark matter, to explore gravitational waves in the mid-frequency range between the peak sensitivities of the LISA and LIGO/Virgo/ KAGRA/INDIGO/Einstein Telescope/Cosmic Explorer experiments, and to probe other frontiers in fundamental physics. AION would complement other planned searches for dark matter, as well as probe mergers involving intermediate mass black holes and explore early universe cosmology. AION would share many technical features with the MAGIS experimental programme in the US, and synergies would flow from operating AION in a network with this experiment, as well as with other atom interferometer experiments such as MIGA, ZAIGA and ELGAR. Operating AION in a network with other gravitational wave detectors such as LIGO, Virgo and LISA would also offer many synergies.

Abstract:

Radiofrequency (RF)-dressed potentials are a promising technique for manipulating atomic mixtures, but so far little work has been undertaken to understand the collisions of atoms held within these traps. In this work, we dress a mixture of 85Rb and 87Rb with RF radiation, characterize the inelastic loss that occurs, and demonstrate species-selective manipulations. Our measurements show the loss is caused by two-body 87Rb+85Rb collisions, and we show the inelastic rate coefficient varies with detuning from the RF resonance. We explain our observations using quantum scattering calculations, which give reasonable agreement with the measurements. The calculations consider magnetic fields both perpendicular to the plane of RF polarization and tilted with respect to it. Our findings have important consequences for future experiments that dress mixtures with RF fields.