Nanoscale Magnetism Probed in a Matter-Wave Interferometer.

We explore a wide range of fundamental magnetic phenomena by measuring the dephasing of matter-wave interference fringes upon application of a variable magnetic gradient. The versatility of our interferometric Stern-Gerlach technique enables us to study the magnetic properties of alkali atoms, organic radicals, and fullerenes in the same device, with magnetic moments ranging from a Bohr magneton to less than a nuclear magneton. We find evidence for magnetization of a supersonic beam of organic radicals and, most notably, observe a strong magnetic response of a thermal C_{60} beam consistent with high-temperature atomlike deflection of rotational magnetic moments.

A fiber-based beam profiler for high-power laser beams in confined spaces and ultra-high vacuum.

Laser beam profilometry is an important scientific task with well-established solutions for beams propagating in air. It has, however, remained an open challenge to measure beam profiles of high-power lasers in ultra-high vacuum and in tightly confined spaces. Here we present a novel scheme that uses a single multi-mode fiber to scatter light and guide it to a detector. The method competes well with commercial systems in position resolution, can reach through apertures smaller than 500×500 µm2 and is compatible with ultra-high vacuum conditions. The scheme is simple, compact, reliable and can withstand laser intensities beyond 2 MW/cm2.

Bragg Diffraction of Large Organic Molecules.

We demonstrate Bragg diffraction of the antibiotic ciprofloxacin and the dye molecule phthalocyanine at a thick optical grating. The observed patterns show a single dominant diffraction order with the expected dependence on the incidence angle as well as oscillating population transfer between the undiffracted and diffracted beams. We achieve an equal-amplitude splitting of 14ℏk (photon momenta) and maximum momentum transfer of 18ℏk. This paves the way for efficient, large-momentum beam splitters and mirrors for hot and complex molecules.

Quantum-assisted diamagnetic deflection of molecules.

We measure the diamagnetic deflection of anthracene and adamantane in a long-baseline matter-wave interferometer. From the nanometer-level deflection we extract the magnetic susceptibilities of the molecules which we compare with calculations and previous results. Adamantane yields an isotropic average mass susceptibility of -8.0 ± 1.1 m3 kg-1, consistent with expectations, while anthracene yields a higher-than-anticipated value of -13.6 ± 1.3 m3 kg-1. We attribute the high anthracene value to the planar aromatic molecule's magnetic anisotropy and partial alignment in the molecular beam, and estimate the magnitude of the effect on the observed deflection.