Atomic Physics

Feshbach resonances in mixtures and refined molecular potentials for the NaK molecule (1810.00608v2)

Torsten Hartmann, Torben A. Schulze, Kai K. Voges, Philipp Gersema, Matthias W. Gempel, Eberhard Tiemann, Alessandro Zenesini, Silke Ospelkaus

2018-10-01

We present a detailed study of interspecies Feshbach resonances of the bosonic mixture for magnetic fields up to in various collision channels. A total of fourteen Feshbach resonances are reported, as well as four zero crossings of the scattering length and three inelastic two-body loss features. We use the observed magnetic field locations of the resonant features together with the known data on to refine the singlet and triplet ground state potentials of NaK and achieve a consistent description of Feshbach resonances for both, the Bose-Bose mixture of as well as the Bose-Fermi mixture of .

Direct Phase Locking of a Ti:Sapphire Optical Frequency Comb to a Remote Optical Frequency Standard (1807.08683v2)

Eunmi Chae, Kota Nakashima, Takuya Ikeda, Kei Sugiyama, Kosuke Yoshioka

2018-07-19

We report on an ultralow noise optical frequency transfer from a remotely located Sr optical lattice clock laser to a Ti:Sapphire optical frequency comb through telecom-wavelength optical fiber networks. The inherent narrow linewidth of the Ti:Sapphire optical frequency comb eliminates the need for a local reference high-finesse cavity. The relative fractional frequency instability of the optical frequency comb with respect to the remote optical reference was at 1 s and at 1,000 s including a 2.9 km-long fiber network. This ensured the optical frequency comb had the same precision as the optical standard. Our result paves the way for ultrahigh-precision spectroscopy and conversion of the highly precise optical frequency to radio frequencies in a simpler setup.

Ultracold homonuclear and heteronuclear collisions in metastable helium (1904.01281v1)

D. G. Cocks, I. B. Whittingham, G. Peach

2019-04-02

Scattering and ionizing cross sections and rates are calculated for ultracold collisions between metastable helium atoms using a fully quantum-mechanical close-coupled formalism. Homonuclear collisions of the bosonic HeHe and fermionic HeHe systems, and heteronuclear collisions of the mixed HeHe system, are investigated over a temperature range 1 K to 1 K. Carefully constructed Born-Oppenheimer molecular potentials are used to describe the electrostatic interaction between the colliding atoms, and complex optical potentials used to represent loss through ionization from the states. Magnetic spin-dipole mediated transitions from the state are included and results reported for spin-polarized and unpolarized systems. Comparisons are made with experimental results, previous semi-classical models, and a perturbed single channel model.

The First Measurement of the Tune-Out Wavelength in He* (1708.08200v2)

B. M. Henson

2017-08-28

The workhorse of atomic physics, quantum electrodynamics, is one of the best-tested theories in physics. However recent discrepancies have shed doubt on its accuracy for complex atomic systems. To facilitate the development of the theory further we aim to measure transition dipole matrix elements of metastable helium (He) (the ideal 3 body test-bed) to the highest accuracy thus far. We have undertaken a measurement of the `tune-out wavelength' which occurs when the contributions to the dynamic polarizability from all atomic transitions sum to zero; thus illuminating an atom with this wavelength of light then produces no net energy shift. This provides a strict constraint on the transition dipole matrix elements without the complication and inaccuracy of other methods. Using a novel atom-laser based technique we have made the first measurement of the tune-out wavelength in metastable helium between the and states at 413.07(2) nm which compares well with the predicted value\cite{Mitroy2013} of 413.02(9) nm. We have additionally developed many of the methods necessary to improve this measurement to the 100 fm level of accuracy where it will form the most accurate determination of transition rate information ever made in He and provide a stringent test for atomic QED simulations. We believe this measurement to be one of the most sensitive ever made of an optical dipole potential, able to detect changes in potentials of 200 pK and is widely applicable to other species and areas of atom optics.

The concept of laser-based conversion electron Mössbauer spectroscopy for a precise energy determination of Th (1904.01245v1)

Lars C. von der Wense, Benedict Seiferle, Christian Schneider, Justin Jeet, Ines Amersdorffer, Nicolas Arlt, Florian Zacherl, Raphael Haas, Dennis Renisch, Patrick Mosel, Philip Mosel, Milutin Kovacev, Uwe Morgner, Christoph E. Düllmann, Eric R. Hudson, Peter G. Thirolf

2019-04-02

Reveal spoiler

Th is the only nucleus currently under investigation for the development of a nuclear optical clock (NOC) of ultra-high accuracy. The insufficient knowledge of the first nuclear excitation energy of Th has so far hindered direct nuclear laser spectroscopy of thorium ions and thus the development of a NOC. Here, a nuclear laser excitation scheme is detailed, which makes use of thorium atoms instead of ions. This concept, besides potentially leading to the first nuclear laser spectroscopy, would determine the isomeric energy to 40 eV resolution, corresponding to 10 GHz, which is a times improvement compared to the current best energy constraint. This would determine the nuclear isomeric energy to a sufficient accuracy to allow for nuclear laser spectroscopy of individual thorium ions in a Paul trap and thus the development of a single-ion nuclear optical clock.

Ab-initio Theory of Photoionization via Resonances (1812.02005v3)

Adi Pick, Petra Ruth Kaprálová-Žďánská, Nimrod Moiseyev

2018-12-04

We present an \emph{ab-initio} approach for computing the photoionization spectrum near autoionization resonances in multi-electron systems. While traditional (Hermitian) theories typically require computing the continuum states, which are difficult to obtain with high accuracy, our non-Hermitian approach requires only discrete bound and metastable states, which are accurately computed with advanced quantum chemistry tools. We derive a simple formula for the absorption lineshape near Fano resonances, which relates the asymmetry of the spectral peaks to the phase of the complex transition dipole moment. Additionally, we present a formula for the ionization spectrum of laser-driven targets and relate the `Autler-Townes' splitting of spectral lines to the existence of exceptional points in the Hamiltonian. We apply our formulas to compute the autoionization spectrum of helium, but our theory is also applicable for non-trivial multi-electron atoms and molecules.

Relativistic non-dipole effects in strong-field atomic ionization at moderate intensities (1808.00137v2)

Nida Haram, Igor Ivanov, Han Xu, Kyung T. Kim, Atia-tul-Noor, U. Satya Sainadh, R. D. Glover, D. Chetty, Igor Litvinyuk, R. T. Sang

2018-08-01

We present a detailed experimental and theoretical study on the relativistic non-dipole effects in strong-field atomic ionisation by near-infrared linearly-polarised few-cycle laser pulses in the intensity range 1014 -1015 W/cm2. We record high-resolution photoelectron momentum distributions of argon using a reaction microscope and compare our measurements with a truly ab-initio fully relativistic 3D model based on the time-dependent Dirac equation. We observe counter-intuitive peak shifts of the transverse electron momentum distribution in the direction opposite to that of laser propagation as a function of laser intensity and demonstrate an excellent agreement between experimental results and theoretical predictions.

Quantum Kibble-Zurek mechanism and critical dynamics on a programmable Rydberg simulator (1809.05540v2)

Alexander Keesling, Ahmed Omran, Harry Levine, Hannes Bernien, Hannes Pichler, Soonwon Choi, Rhine Samajdar, Sylvain Schwartz, Pietro Silvi, Subir Sachdev, Peter Zoller, Manuel Endres, Markus Greiner, Vladan Vuletic, Mikhail D. Lukin

2018-09-14

Quantum phase transitions (QPTs) involve transformations between different states of matter that are driven by quantum fluctuations. These fluctuations play a dominant role in the quantum critical region surrounding the transition point, where the dynamics are governed by the universal properties associated with the QPT. While time-dependent phenomena associated with classical, thermally driven phase transitions have been extensively studied in systems ranging from the early universe to Bose Einstein Condensates, understanding critical real-time dynamics in isolated, non-equilibrium quantum systems is an outstanding challenge. Here, we use a Rydberg atom quantum simulator with programmable interactions to study the quantum critical dynamics associated with several distinct QPTs. By studying the growth of spatial correlations while crossing the QPT, we experimentally verify the quantum Kibble-Zurek mechanism (QKZM) for an Ising-type QPT, explore scaling universality, and observe corrections beyond QKZM predictions. This approach is subsequently used to measure the critical exponents associated with chiral clock models, providing new insights into exotic systems that have not been understood previously, and opening the door for precision studies of critical phenomena, simulations of lattice gauge theories and applications to quantum optimization.

Isotopic variation of parity violation in atomic ytterbium: method of measurements and analysis of systematic effects (1903.06326v2)

D. Antypas, A. M. Fabricant, J. E. Stalnaker, K. Tsigutkin, V. V. Flambaum, D. Budker

2019-03-15

We present a detailed description of experimental studies of the parity violation effect in an isotopic chain of atomic ytterbium (Yb), whose results were reported in a recent Letter [Antypas et al., Nat. Phys. 15, 120 (2019)]. We discuss the principle of these measurements, made on the Yb 6s S5d6s D optical transition at 408 nm, describe the experimental apparatus, and give a detailed account of our studies of systematic effects in the experiment. Our results offer the first direct observation of the isotopic variation in the atomic parity violation effect, a variation which is in agreement with the prediction of the Standard Model. These measurements are used to constrain electron-proton and electron-neutron interactions, mediated by a light boson.

Quantifying and controlling prethermal nonergodicity in interacting Floquet matter (1809.05554v3)

Kevin Singh, K. M. Fujiwara, Zachary A. Geiger, Ethan Q. Simmons, Mikhail Lipatov, Alec Cao, Peter Dotti, Shankari V. Rajagopal, Ruwan Senaratne, Toshihiko Shimasaki, Markus Heyl, André Eckardt, David M. Weld