Atomic Physics

---

Resolution-enhanced quantitative spectroscopy of atomic vapor in optical nanocells based on second-derivative processing of spectra (1906.06252v1)

Armen Sargsyan, Arevik Amiryan, Yevgenya Pashayan-Leroy, Claude Leroy, Aram Papoyan, David Sarkisyan

2019-06-14

We present a method for recovery of narrow homogeneous spectral features out of broad inhomogeneous overlapped profile based on second-derivative processing of the absorption spectra of alkali metal atomic vapor nanocells. The method is shown to preserve the frequency positions and amplitudes of spectral transitions, thus being applicable for quantitative spectroscopy. The proposed technique was successfully applied and tested for: measurements of hyperfine splitting and atomic transition probabilities; development of an atomic frequency reference; determination of isotopic abundance; study of atom-surface interaction; and determination of magnetic field-induced modification of atomic transitions frequency and probability. The obtained experimental results are fully consistent with theoretical modeling.

Universal scheme for integrating cold atoms into optical waveguides (1906.06236v1)

Elisa Da Ros, Nathan Cooper, Jonathan Nute, Lucia Hackermueller

2019-06-14

Hybrid quantum devices, incorporating both atoms and photons, can exploit the benefits of both to enable scalable architectures for quantum computing and quantum communication, as well as chip-scale sensors and single-photon sources. Production of such devices depends on the development of an interface between their atomic and photonic components. This should be compact, robust and compatible with existing technologies from both fields. Here we demonstrate such an interface. Cold caesium atoms are trapped inside a transverse, 30 m diameter through-hole in an optical fibre, created via laser micromachining. When the guided light is on resonance with the caesium line, up to 87% of it is absorbed by the atoms. The corresponding optical depth per unit length is 700 cm, higher than any reported for a comparable system. This is important for miniaturisation and scalability. The technique should be equally effective in optical waveguide chips and other existing photonic systems.

Two-center electron-impact ionization via collisional excitation-autoionization (1906.06137v1)

F. Grüll, A. B. Voitkiv, C. Müller

2019-06-14

Electron-impact ionization of an atom or ion in the presence of a neighboring atom is studied. The latter is first collisionally excited by the incident electron, whose energy is assumed to be high but nonrelativistic. Afterwards, the excitation energy is transferred radiationlessly via a two-center Auger process to the other atom or ion, leading to its ionization. We show that the participation of the neighboring atom manifests in a very pronounced resonance peak in the energy-differential cross section and can substantially enhance the total cross section of electron-impact ionization. We also discuss the influence of the neighbouring atom on the angular distribution of the ejected electron.

Splitting and recombination of bright-solitary-matter waves (1906.06083v1)

Oliver J. Wales, Ana Rakonjac, Thomas P. Billam, John L. Helm, Simon A. Gardiner, Simon L. Cornish

2019-06-14

Solitons are long-lived wavepackets that propagate without dispersion and exist in a wide range of one-dimensional (1D) nonlinear systems. A Bose-Einstein condensate trapped in a quasi-1D waveguide can support bright-solitary-matter waves (3D analogues of solitons) when interatomic interactions are sufficiently attractive that they cancel dispersion. Solitary-matter waves are excellent candidates for a new generation of highly sensitive interferometers, as their non-dispersive nature allows them to acquire phase shifts for longer times than conventional matter-waves interferometers. However, such an interferometer is yet to be realised experimentally. In this work, we demonstrate the splitting and recombination of a bright-solitary-matter wave on a narrow repulsive barrier, which brings together the fundamental components of an interferometer. We show that both interference-mediated recombination and classical velocity filtering effects are important, but for a sufficiently narrow barrier interference-mediated recombination can dominate. We reveal the extreme sensitivity of interference-mediated recombination to the experimental parameters, highlighting the potential of soliton interferometry.

JILA SrI Optical Lattice Clock with Uncertainty of (1906.06004v1)

Tobias Bothwell, Dhruv Kedar, Eric Oelker, John M. Robinson, Sarah L. Bromley, Weston L. Tew, Jun Ye, Colin J. Kennedy

2019-06-14

We report on an improved systematic evaluation of the JILA SrI optical lattice clock, achieving a nearly identical systematic uncertainty compared to the previous strontium accuracy record set by the JILA SrII optical lattice clock (OLC) at . This improves upon the previous evaluation of the JILA SrI optical lattice clock in 2013, and we achieve a more than twenty-fold reduction in systematic uncertainty to . A seven-fold improvement in clock stability, reaching for an averaging time in seconds, allows the clock to average to its systematic uncertainty in under 10 minutes. We improve the systematic uncertainty budget in several important ways. This includes a novel scheme for taming blackbody radiation-induced frequency shifts through active stabilization and characterization of the thermal environment, inclusion of higher-order terms in the lattice light shift, and updated atomic coefficients. Along with careful control of other systematic effects, we achieve low temporal drift of systematic offsets and high uptime of the clock. We additionally present an improved evaluation of the second order Zeeman coefficient that is applicable to all Sr optical lattice clocks. These improvements in performance have enabled several important studies including frequency ratio measurements through the Boulder Area Clock Optical Network (BACON), a high precision comparison with the JILA 3D lattice clock, a demonstration of a new all-optical time scale combining SrI and a cryogenic silicon cavity, and a high sensitivity search for ultralight scalar dark matter.

Observation of interference between resonant and detuned STIRAP in the adiabatic creation of NaK molecules (1906.05974v1)

Lan Liu, De-Chao Zhang, Huan Yang, Ya-Xiong Liu, Jue Nan, Jun Rui, Bo Zhao, Jian-Wei Pan

2019-06-14

Stimulated Raman adiabatic passage (STIRAP) allows to efficiently transferring the populations between two discrete quantum states and has been used to prepare molecules in their rovibrational ground state. In realistic molecules, a well-resolved intermediate state is usually selected to implement the resonant STIRAP. Due to the complex molecular level structures, the detuned STIRAP always coexists with the resonant STIRAP and may cause unexpected interference phenomenon. However, it is generally accepted that the detuned STIRAP can be neglected if compared with the resonant STIRAP. Here we report on the first observation of interference between the resonant and detuned STIRAP in the adiabatic creation of NaK ground-state molecules. The interference is identified by observing that the number of Feshbach molecules after a round-trip STIRAP oscillates as a function of the hold time, with a visibility of about 90%. This occurs even if the intermediate excited states are well resolved, and the single-photon detuning of the detuned STIRAP is about one order of magnitude larger than the linewidth of the excited state and the Rabi frequencies of the STIRAP lasers. Moreover, the observed interference indicates that if more than one hyperfine level of the ground state is populated, the STIRAP prepares a coherent superposition state among them, but not an incoherent mixed state. Further, the purity of the hyperfine levels of the created ground state can be quantitatively determined by the visibility of the oscillation.

A quasiclassical method for calculating the density of states of ultracold collision complexes (1905.06691v2)

Arthur Christianen, Tijs Karman, Gerrit C. Groenenboom

2019-05-16

We derive a quasiclassical expression for the density of states (DOS) of an arbitrary, ultracold, -atom collision complex, for a general potential energy surface (PES). We establish the accuracy of our quasiclassical method by comparing to exact quantum results for the K-Rb and NaK-NaK systems, with isotropic model PESs. Next, we calculate the DOS for an accurate NaK-NaK PES to be 0.124~K, with an associated Rice-Ramsperger-Kassel-Marcus (RRKM) sticking time of 6.0~s. We extrapolate the DOS and sticking times to all other polar bialkali-bialkali collision complexes by scaling with atomic masses, equilibrium bond lengths, dissociation energies, and dispersion coefficients. The sticking times calculated here are two to three orders of magnitude shorter than those reported by Mayle et al. [Phys. Rev. A 85, 062712 (2012)]. We estimate dispersion coefficients and collision rates between molecules and complexes. We find that the sticking-amplified three-body loss mechanism is not likely the cause of the losses observed in the experiments.

Trapping laser excitation during collisions limits the lifetime of ultracold molecules (1905.06846v2)

Arthur Christianen, Martin W. Zwierlein, Gerrit C. Groenenboom, Tijs Karman

2019-05-16

The lifetime of nonreactive ultracold bialkali gases was conjectured to be limited by sticky collisions amplifying three-body loss. We show that the sticking times were previously overestimated and do not support this hypothesis. We find that electronic excitation of NaK+NaK collision complexes by the trapping laser leads to the experimentally observed two-body loss. We calculate the excitation rate with a quasiclassical, statistical model employing ab initio potentials and transition dipole moments. Using longer laser wavelengths or repulsive box potentials may suppress the losses.

Shell potentials for microgravity Bose-Einstein condensates (1906.05885v1)

N. Lundblad, R. A. Carollo, C. Lannert, M. J. Gold, X. Jiang, D. Paseltiner, N. Sergay, D. C. Aveline

2019-06-13

Extending the understanding of Bose-Einstein condensate (BEC) physics to new geometries and topologies has a long and varied history in ultracold atomic physics. One such new geometry is that of a bubble, where a condensate would be confined to the surface of an ellipsoidal shell. Study of this geometry would give insight into new collective modes, self-interference effects, topology-dependent vortex behavior, dimensionality crossovers from thick to thin shells, and the properties of condensates pushed into the ultradilute limit. Here we discuss a proposal to implement a realistic experimental framework for generating shell-geometry BEC using radiofrequency dressing of magnetically-trapped samples. Such a tantalizing state of matter is inaccessible terrestrially due to the distorting effect of gravity on experimentally-feasible shell potentials. The debut of an orbital BEC machine (NASA Cold Atom Laboratory, aboard the International Space Station) has enabled the operation of quantum-gas experiments in a regime of perpetual freefall, and thus has permitted the planning of microgravity shell-geometry BEC experiments. We discuss specific experimental configurations, applicable inhomogeneities and other experimental challenges, and outline potential experiments.

Precision measurement of atomic isotope shifts using a two-isotope entangled state (1906.05770v1)

Tom Manovitz, Ravid Shaniv, Yotam Shapira, Roee Ozeri, Nitzan Akerman

2019-06-13

Atomic isotope shifts (ISs) are the isotope-dependent energy differences in the atomic electron energy levels. These shifts serve an important role in atomic and nuclear physics, and particularly in the latter as signatures of nuclear structure. Recently ISs have been suggested as unique probes of beyond Standard Model (SM) physics, under the condition that they be determined significantly more precisely than current state of the art. In this work we present a simple and robust method for measuring ISs with ions in a Paul trap, by taking advantage of Hilbert subspaces that are insensitive to common-mode noise yet sensitive to the IS. Using this method we evaluate the IS of the transition in and with a relative uncertainty to be 570,264,063.435(9) Hz. Furthermore, we detect a relative difference of between the orbital g-factors of the electrons in the level of the two isotopes. Our method is relatively easy to implement and is indifferent to element or isotope, paving the way for future tabletop searches for new physics and posing interesting prospects for testing quantum many-body calculations and for the study of nuclear structure.

---

Keeping updated in the latest research in atomic and molecular clusters!