Atomic Physics Latest Preprints | 2019-04-14
Atomic Physics
Imaging recoil ions from optical collisions between ultracold, metastable neon isotopes (1904.05672v1)
B. Ohayon, H. Rahangdale, J. Chocron, R. Kosloff, O. Heber, G. Ron
2019-04-11
We present an experimental scheme which combines the well established method of velocity-mapimaging, with a cold trapped metastable neon target. The device is used for obtaining the branching ratios and recoil-ion energy distributions for the penning ionization process in optical collisions of ultracold metastable neon. The potential depth of the highly excited dimer potential is extracted and compared with theoretical calculations. The simplicity to construct, characterize and apply such a device, makes it a unique tool for the low-energy nuclear physics community, enabling opportunities for precision measurements in beta- and beta-delayed-neutron decays of cold, trapped, short-lived radioactive isotopes.
Observation of spin-structure of ultralong-range Rydberg molecules (1901.08792v2)
Markus Deiß, Shinsuke Haze, Joschka Wolf, Limei Wang, Florian Meinert, Christian Fey, Frederic Hummel, Peter Schmelcher, Johannes Hecker Denschlag
2019-01-25
We present an experimental and theoretical study of the spin- and vibrational states of
ultralong-range Rb
Rydberg molecules that are bound in the second outermost potential well. Due to resonant
-wave interaction, the admixture of a butterfly state, and the combination of spin-spin and spin-orbit couplings these molecules feature non-trivial spin state energy level manifolds. By carrying out Rydberg spectroscopy we observe several vibrational ladders. Each ladder exhibits a characteristic multiplet substructure which facilitates assigning a spin state to each level. Our calculations show that a specific type of spin-orbit interaction can significantly contribute to the multiplet line splittings. This spin-orbit interaction is given by the coupling between the total electron spin and the orbital angular momentum of the Rydberg electron in the reference frame of the ground state atom. Furthermore, we find that the diabaticity of the molecular motion across an avoided crossing in the potential energy curve has a strong impact on the vibrational level structure. Our investigation paves the way for further in-depth studies of subtle interaction mechanisms in Rydberg molecules.
Highly efficient isotope separation and ion implantation of 
Ho for the ECHo project (1904.05559v1)
Tom Kieck, Holger Dorrer, Christoph E. Düllmann, Vadim Gadelshin, Fabian Schneider, Klaus Wendt
2019-04-11
The effective electron neutrino mass measurement at the ECHo experiment requires high purity
magnetic mass separator RISIKO. This achieved ionization and separation efficiencies with an average of
using intra-cavity frequency doubled Ti:sapphire lasers. The implantation of a
Ho impurity is suppressed about five orders of magnitude by the mass separation. A dedicated implantation stage with focusing and scanning capability enhances the geometric implantation efficiency into the ECHo detectors to
.
Spin-exchange-induced exotic superfluids in a Bose-Fermi spinor mixture (1904.05486v1)
Chuanzhou Zhu, Li Chen, Hui Hu, Xia-Ji Liu, Han Pu
2019-04-11
We consider a mixture of spin-1/2 bosons and fermions, where only the bosons are subjected to the spin-orbit coupling induced by Raman beams. The fermions, although not directly coupled to the Raman lasers, acquire an effective spin-orbit coupling through the spin-exchange interaction between the two species. Our calculation shows that this is a promising way of obtaining spin-orbit coupled Fermi gas without Raman-induced heating, where the long-sought topological Fermi superfluids and topological bands can be realized. Conversely, we find that the presence of fermions not only provides a new way to create the supersolid stripe phase of the bosons, but more strikingly it can also greatly increase the spatial period of the bosonic density stripes, and hence makes this phase directly observable in experiment. This system provides a new and practical platform to explore the physics of spin-orbit coupling.
Bose polarons near quantum criticality (1904.02685v2)
Zoe Z. Yan, Yiqi Ni, Carsten Robens, Martin W. Zwierlein
2019-04-04
The emergence of quasiparticles in strongly interacting matter represents one of the cornerstones of modern physics. However, when different phases of matter compete near a quantum critical point, the very existence of quasiparticles comes under question. Here we create Bose polarons near quantum criticality by immersing atomic impurities in a Bose-Einstein condensate (BEC) with near-resonant interactions. Using locally-resolved radiofrequency spectroscopy, we probe the energy, spectral width, and short-range correlations of the impurities as a function of temperature. Far below the superfluid critical temperature, the impurities form well-defined quasiparticles. However, their inverse lifetime, given by their spectral width, is observed to increase linearly with temperature, a hallmark of quantum critical behavior. Close to the BEC critical temperature, the spectral width exceeds the binding energy of the impurities, signaling a breakdown of the quasiparticle picture near quantum criticality.
Reconstruction of tunnel exit time and exit momentum in strong field ionization, based on phase space methods (1904.05465v1)
Szabolcs Hack, Szilárd Majorosi, Mihály Benedict, Attila Czirják
2019-04-10
We analyze tunnel ionization of a single atom based on the Wigner function over the classical phase space which inspires improved classical electron trajectories: these start with exit momenta based on the quantum momentum function and correspond very well to the subsequent quantum evolution. We derive an approximate analytic formula to reconstruct the tunnel exit time and exit momentum from electron momentum data that can be measured e.g. with a usual time-of-flight electron detector.
Single photoionization of the Kr-like Rb II ion in the photon energy range 22 - 46.0 eV (1903.06032v2)
Brendan M. McLaughlin, James F. Babb
2019-03-13
Single photoionization cross sections for Kr-like Rb
ions are reported in the energy (wavelength) range 22 eV (564 \AA) to 46 eV (270 \AA). Theoretical cross section calculations for this {\it trans}-Fe element are compared with measurements from the ASTRID radiation facility in Aarhus, Denmark and the dual laser plasma (DLP) technique, at respectively 40 meV and 35 meV FWHM energy resolution. In the photon energy region 22 - 32 eV the spectrum is dominated by excitation autoionizing resonance states. Above 32 eV the cross section exhibit classic Fano window resonances features, which are analysed and discussed. Large-scale theoretical photoionization cross-section calculations, performed using a Dirac Coulomb
-matrix approximation are bench marked against these high resolution experimental results. Comparison of the theoretical work with the experimental studies allowed the identification of resonance features and their parameters in the spectra in addition to contributions from excited metastable states of the Rb
Characterizing a statistical arrow of time in quantum measurement dynamics (1811.07708v2)
P. M. Harrington, D. Tan, M. Naghiloo, K. W. Murch
2018-11-19
In both thermodynamics and quantum mechanics the arrow of time is characterized by the statistical likelihood of physical processes. We characterize this arrow of time for the continuous quantum measurement dynamics of a superconducting qubit. By experimentally tracking individual weak measurement trajectories, we compare the path probabilities of forward and backward-in-time evolution to develop an arrow of time statistic associated with measurement dynamics. We compare the statistics of individual trajectories to ensemble properties showing that the measurement dynamics obeys both detailed and integral fluctuation theorems thus establishing the consistency between microscopic and macroscopic measurement dynamics.
Exploring Non-Abelian Geometric Phases in Spin-1 Ultracold Atoms (1801.00586v2)
H. M. Bharath, Matthew Boguslawski, Maryrose Barrios, Lin Xin, M. S. Chapman
2018-01-02
Non-Abelian and non-adiabatic variants of Berry's geometric phase have been pivotal in the recent advances in fault tolerant quantum computation gates, while Berry's phase itself is at the heart of the study of topological phases of matter. The geometrical and topological properties of the phase space of spin
quantum states is richer than that of spin
quantum states and is relatively unexplored. For instance, the spin vector of a spin-1 system, unlike that of a spin
, which is more non-trivial. Here we use coherent control of ultracold
Rb atoms in an optical trap to experimentally explore this geometric phase for singular loops in a spin-1 quantum system.
High-energy bremsstrahlung on atoms in a laser field (1904.05094v1)
P. A. Krachkov, A. Di Piazza, A. I. Milstein
2019-04-10
The impact of a laser field on the process of photon radiation by an ultra-relativistic electron in an atomic field is investigated. The angular distribution and the spectrum of the radiated photon are derived. By means of the quasiclassical approximation, the obtained results are exact in the parameters of the laser field and the atomic field. It is shown that the impact of the laser field is significant even for fairly average values of the laser field parameters routinely achievable nowadays. Therefore, an experimental observation of the influence of the laser field on bremsstrahlung in the atomic field is a very feasible task.
