arXiv subjects

Stephan Schneider

Publications and source records attributed to Stephan Schneider.

5 recordsLinked to original sources

arXiv2026

Searching in HI for Massive Low Surface Brightness Galaxies: II. Completing the UGC Sample

Although Low Surface Brightness (LSB) galaxies are increasingly well studied, considerable uncertainty still exists as to both their range in properties and their evolutionary history. LSB galaxies provide a fascinating extreme in galaxy formation and evolution, allowing excellent tests of galaxy formation and evolution theories. Previously, our group successfully measured the HI gas and dynamical mass properties of 350 LSB galaxies, significantly increasing the number of known extreme LSB galaxies (massive, gas rich, etc.) in the process. Here we oresent 100-m Robert C. Byrd Green Bank Telescope 21-cm HI line observations of a further 35 LBG galaxies, only two of which have previously published data. Of the 35, 19 were detected. This paper also includes the HI information for five additional galaxies detected accidentally (in the blank sky region or at alternative velocities), none of which has previously published HI results.

astro-ph.GA↗

arXiv2023

Integrating Superregenerative Principles in a Compact, Power-Efficient NMR/NQR Spectrometer: A Novel Approach with Pulsed Excitation

We present a new approach to Nuclear Quadrupole Resonance (NQR)/Nuclear Magnetic Resonance (NMR) spectroscopy, the Damp-Enhanced Superregenerative Nuclear Spin Analyser (DESSA). This system integrates Superregenerative principles with pulsed sample excitation and detection, offering significant advancements over traditional Super-Regenerative Receivers (SRRs). Our approach overcomes certain limitations associated with traditional Super-Regenerative Receivers (SRRs) by integrating direct digital processing of the oscillator response delay time (T$_d$) and an electronic damp unit to regulate the excitation pulse decay time (T$_e$). The essence is combining pulsed excitation with a reception inspired by, but distinct from, conventional SRRs. The damp unit allows a rapid termination of the oscillation pulse and the initiation of detection within microseconds, and direct digital processing avoids the need for a second lower frequency which is used for quenching in a traditional SRRs, thereby avoiding the formation of sidebands. We demonstrate the effectiveness of DESSA on a \ch{NaClO3} sample containing the isotope Chlorine-35 where it accurately detects the NQR signal with sub-kHz resolution.

physics.ins-det↗

arXiv2014

Magnetic conveyor belt transport of ultracold atoms to a superconducting atomchip

We report the realization of a robust magnetic transport scheme to bring 3x10^8 ultracold 87Rb atoms into a cryostat. The sequence starts with standard laser cooling and trapping of 87Rb atoms, transporting first horizontally and then vertically through the radiation shields into a cryostat by a series of normal- and superconducting magnetic coils. Loading the atoms in a superconducting microtrap paves the way for studying the interaction of ultracold atoms with superconducting surfaces and quantum devices requiring cryogenic temperatures.

quant-ph↗

arXiv2011

Cavity QED with magnetically coupled collective spin states

We report strong coupling between an ensemble of nitrogen-vacancy center electron spins in diamond and a superconducting microwave coplanar waveguide resonator. The characteristic scaling of the collective coupling strength with the square root of the number of emitters is observed directly. Additionally, we measure hyperfine coupling to 13C nuclear spins, which is a first step towards a nuclear ensemble quantum memory. Using the dispersive shift of the cavity resonance frequency, we measure the relaxation time T1 of the NV center at millikelvin temperatures in a non-destructive way.

cond-mat.mes-hall↗

arXiv2011

Absorption Imaging of Ultracold Atoms on Atom Chips

Imaging ultracold atomic gases close to surfaces is an important tool for the detailed analysis of experiments carried out using atom chips. We describe the critical factors that need be considered, especially when the imaging beam is purposely reflected from the surface. In particular we present methods to measure the atom-surface distance, which is a prerequisite for magnetic field imaging and studies of atom surface-interactions.

physics.atom-ph↗