arXiv subjects

Benjamin Deissler

Publications and source records attributed to Benjamin Deissler.

3 recordsLinked to original sources

arXiv2019

Pair fraction in a finite temperature Fermi gas on the BEC side of the BCS-BEC crossover

We investigate pairing in a strongly interacting two-component Fermi gas with positive scattering length. In this regime, pairing occurs at temperatures above the superfluid critical temperature; unbound fermions and pairs coexist in thermal equilibrium. Measuring the total number of these fermion pairs in the gas we systematically investigate the phases in the sectors of pseudogap and preformed-pair. Our measurements quantitatively test predictions from two theoretical models. Interestingly, we find that already a model based on classical atom-molecule equilibrium describes our data quite well.

cond-mat.quant-gas↗

arXiv2016

Holographic method for site-resolved detection of a 2D array of ultracold atoms

We propose a novel approach to site-resolved detection of a 2D gas of ultracold atoms in an optical lattice. A near resonant laser beam is coherently scattered by the atomic array and its interference pattern is holographically recorded by superimposing it with a reference laser beam on a CCD chip. Fourier transformation of the recorded intensity pattern reconstructs the atomic distribution in the lattice with single-site resolution. The holographic detection method requires only a few hundred scattered photons per atom in order to achieve a high reconstruction fidelity. Therefore, additional cooling during detection might not be necessary even for light atomic elements such as lithium.

cond-mat.quant-gas↗

arXiv2015

Probing the axis alignment of an ultracold spin-polarized $\textrm{Rb}_2$ molecule

We present a novel method for probing the alignment of the molecular axis of an ultracold, nonpolar dimer. These results are obtained using diatomic $^{87}\textrm{Rb}_2$ molecules in the vibrational ground state of the lowest triplet potential $a^3Σ_u^+$ trapped in a 3D optical lattice. We measure the molecular polarizabilities, which are directly linked to the alignment, along each of the $x$, $y$, and $z$ directions of the lab coordinate system. By preparing the molecules in various, precisely defined rotational quantum states we can control the degree of alignment of the molecular axis with high precision over a large range. Furthermore, we derive the dynamical polarizabilities for a laser wavelength of $1064.5\:\textrm{nm}$ parallel and orthogonal to the molecular axis of the dimer, $α_\parallel=(8.9 \pm 0.9)\times10^3\:\textrm{a.u.}$ and $α_\perp=(0.9 \pm 0.4)\times10^3\:\textrm{a.u.}$, respectively. Our findings highlight that the depth of an optical lattice strongly depends on the rotational state of the molecule which has to be considered in collision experiments. The present work paves the way for reaction studies between aligned molecules in the ultracold temperature regime.

physics.atom-ph↗