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We present the first observation of ultracold LiCs molecules. The molecules are formed in a two-species magneto-optical trap and detected by two-photon ionization and time-of-flight mass spectrometry. |
We compare the electron dynamics at monocrystalline Cu(111), Au(100) and Pd(111) precursor substrates with vicinal nanosteps. The unoccupied bands of a surface superlattice are populated \textit{via} the resonant charge transfer (RCT) between the surface and a H$^-$ ion that flies by at grazing angles. |
We report the magnetic confinement of neutral, ground state hydroxyl radicals (OH) at a density of $\sim3\times10^{3}$ cm$^{-3}$ and temperature of $\sim$30 mK. An adjustable electric field of sufficient magnitude to polarize the OH is superimposed on the trap in either a quadrupole or homogenous field geometry. |
We experimentally investigate the dynamical instability of a Bose Einstein condensate in an optical ring resonator for various cavity detuning and pump powers. The resulting phase diagram is asymmetric with respect to the cavity detuning and can be described by the coupling of two atomic modes with one optical mode. |
Considering light-mediated long-range interactions between cold atoms in a magneto-optical trap (MOT), we present numerical evidence of a nonequilibrium steady state (NESS) for sufficiently large number of atoms (> 10^8). This state manifests itself as the appearance of an anisotropic distribution of velocity when ... |
We investigate the interaction between three rubidium atoms in highly excited ($58p$) Rydberg states lying along a common axis and calculate the potential energy surfaces (PES) between the three atoms. We find that three-body long-range potential wells exist in some of these surfaces, indicating the existence of very ... |
The status of our understanding of relativistic sum rules is reviewed. The recent development of new theoretical methods for the evaluation of these sum rules offers hope for further advances in this challenging field. |
Polar molecules in selected quantum states can be guided, decelerated and trapped using electric fields created by microstructured electrodes on a chip. Here we explore how non-adiabatic transitions between levels in which the molecules are trapped and levels in which the molecules are not trapped can be suppressed. |
Three body resonant interactions between Rydberg atoms are considered in order to perform few-body quantum gates. So far, the resonances found in cesium or rubidium atoms relied on an adjacent two-body resonance which ceases to exist for principal quantum numbers above $n \simeq 40$. |
We present a method to tune the resonantly enhanced harmonic emission from engineered potentials, which would be experimentally feasible in the purview of the recent advances in atomic and condensed matter physics. The recombination of the electron from the potential dependent excited state to the ground state causes ... |
This paper presents two new adiabatic, global potential energy surfaces (PESs) for the two lowest $^3A'$ and $^3A''$ electronic states of the O($^3P$)+H$_2$ system. For each of these states, ab initio electronic energies were calculated for more than 5000 geometries using internally contracted multireferen... |
The main goal of the present work is to estimate the effects of plasma environment on the atomic parameters associated with the K-vacancy states in highly charged iron ions within the astrophysical context of accretion disks around black holes. In order to do this, multiconfiguration Dirac-Fock computations have been ... |
We demonstrate an improvement in short-term stability by a factor of 10 over a previous generation miniature buffer gas cooled trapped ion clock. We describe the enhancement to detection SNR that has enabled this improvement, the method of clock operation, and the measurement of clock short-term stability. |
In the extreme near-field, when the spatial extension of the atomic wavefunction is no longer negligible compared to the atom-surface distance, the dipole approximation is no longer sufficient to describe Casimir-Polder interactions. Here we calculate the higher-order, quadrupole and octupole, contributions to Casimir... |
Atomic data determined by analysis of observed atomic spectra are essential for plasma diagnostics. For each low-ionisation open d- and f-subshell atomic species, around $10^3$ fine structure level energies can be determined through years of analysis of $10^4$ observable spectral lines. |
High precision multipole polarizabilities, $\alpha_{\ell}$ for $\ell \le 4$ of the $1s$ ground state of the hydrogen isoelectronic series are obtained from the Dirac equation using the B-spline method with Notre Dame boundary conditions. Compact analytic expressions for the polarizabilities as a function of $Z$ with a... |
We propose a hybrid quantum system, where an $LC$ resonator inductively interacts with a flux qubit and is capacitively coupled to a Rydberg atom. Varying the external magnetic flux bias controls the flux-qubit flipping and the flux qubit-resonator interface. |
A novel technique to sensitively and selectively isolate multiple-quantum coherences in a femtosecond pump-probe setup is presented. Detecting incoherent observables and imparting lock-in amplification, even weak signals of highly dilute samples can be acquired. |
We theoretically study the process of photoelectron emission of the Helium atom by a high-intensity short-wavelength laser at a resonance condition of the residual singly charged ion. Photoionization followed by strong resonance coupling in the ion leads to a change in the photoelectron spectrum due to Rabi oscillatio... |
We demonstrate the use of the ultrafast spatial coherent-control method to resolve the fine-structure two-photon transitions of atomic rubidium. Counter-propagating ultrafast optical pulses with spectral phase and amplitude programmed with our optimized solutions successfully induced the two-photon transitions through... |
We present a theoretical study of elastic photon scattering by atomic targets. This process is of special interest since various channels from atomic and nuclear physics as well as quantum elctrodynamics (QED) contribute to it. |
The reaction between He$^+$ and CH$_3$F forming predominantly CH$_2^+$ and CHF$^+$ has been studied at collision energies $E_{\rm coll}$ between 0 and $k_{\rm B}\cdot 10$~K in a merged-beam apparatus. To avoid heating of the ions by stray electric fields, the reaction was observed within the orbit of a highly excited ... |
Using the recently developed concept of the 2-electron streak camera (see NJP 12, 103024 (2010)), we have studied the energy-sharing between the two ionizing electrons in single-photon double ionization of He(1s2s). We find that the most symmetric and asymmetric energy sharings correspond to different ionization dynam... |
We propose a scheme to simulate lattice spin models based on strong and long-range interacting Rydberg atoms stored in a large-spacing array of magnetic microtraps. Each spin is encoded in a collective spin state involving a single $nP$ Rydberg atom excited from an ensemble of ground-state alkali atoms prepared via Ry... |
Photoelectron angular distributions of the two-photon ionization of neutral atoms are theoretically investigated. Numerical calculations of two-photon ionization cross sections and asymmetry parameters are carried out within the independent-particle approximation and relativistic second-order perturbation theory. |
Motivated by the emerging experiments [e.g. \textit{Z. Nie et al. |
The results of studies on the properties of ordinary and heavy water subjected to sharp mechanical impacts at acoustic repetition frequency are presented. Experimental evidence for the phenomenon of acoustically induced nuclear processes in water is provided, supported by direct measurements of radiation emission and ... |
The multiphoton ionization and photoelectron spectra of magnesium were studied at laser intensities of up to 6x10^{13} Wcm^{-2} using 150 fs laser pulses of a wavelength of 400 nm. The results indicated that a variety of different ionization mechanisms played a role in both types of spectra. |
We present a multiplexed quantum repeater protocol based on an ensemble of laser-cooled and trapped rubidium atoms inside an optical ring cavity. We have already demonstrated strong collective coupling in such a system and have constructed a multiplexing apparatus based on a two-dimensional acousto-optical deflector. |
Corrections to energy levels in light muonic atoms are investigated in order $\alpha^2(Z\alpha)^4m$. We pay attention to corrections which are specific for muonic atoms and include the electron vacuum polarization loop. |
We review current status of the study of parity and time invariance phenomena in atoms, nuclei and molecules. We focus on three most promising areas of research: |
We study the influence of the lattice topography and the coupling between motion in different directions, for a three-dimensional Brownian motor based on cold atoms in a double optical lattice. Due to controllable relative spatial phases between the lattices, our Brownian motor can induce drifts in arbitrary direction... |
Recently, S. Aggarwal [Chin. Phys. B 23 (2014) 093203] reported energy levels, radiative rates and lifetimes for the lowest 60 levels belonging to the 2s$^2$2p$^5$, 2s2p$^6$ and 2s$^2$2p$^4$3$\ell$ configurations of F-like tungsten. There is no discrepancy for his calculated energies for the levels and the radiative r... |
Multi-step laser resonance ionization spectroscopy of lutetium (Lu) has been performed at TRIUMF's off-line laser ion source test stand. The even-parity Rydberg series $6s^2nd$ $^2D_{3/2}$, $6s^2nd$ $^2D_{5/2}$ and $6s^2ns$ $^2S_{1/2}$ were observed converging to the 6s$^2$ ionization potential. |
Magnetic Feshbach resonances are an invaluable tool for controlling ultracold atoms and molecules. They can be used to tune atomic interactions and have been used extensively to explore few- and many-body phenomena. |
Two-loop self-energy corrections to the bound-electron $g$ factor are investigated theoretically to all orders in the nuclear binding strength parameter $Z\alpha$. The separation of divergences is performed by dimensional regularization, and the contributing diagrams are regrouped into specific categories to yield fin... |
Parity and time-reversal violating electric dipole moment (EDM) of $^{171}$Yb is calculated accounting for the electron correlation effects over the Dirac-Hartree-Fock (DHF) method in the relativistic Rayleigh-Schrödinger many-body perturbation theory, with the second (MBPT(2) method) and third order (MBPT(3) method) a... |
We present first results on ultrafast X-ray scattering of strongly driven molecular Iodine and analysis of high-order anisotropic components of the scattering signal, up to four-photon absorption. We discuss the technical details of retrieving high fidelity high-order anisotropy components, and outline a method to ana... |
An efficient $\lambda/2$-method ($\lambda$ is the resonant wavelength of laser radiation) based on nanometric-thickness cell filled with rubidium is implemented to study the splitting of hyperfine transitions of $^{85}$Rb and $^{87}$Rb $D_2$ lines in an external magnetic field in the range of $B =3$~kG -- 7~kG. It is ... |
An ion in a radiofrequency ion trap interacting with a buffer gas of ultracold neutral atoms is a driven dynamical system which has been found to develop a non-thermal energy distribution with a power law tail. The exact analytical form of this distribution is unknown, but has often been represented empirically by q-e... |
We present the accurate measurement of the frequency of the $7S-7P$ laser-trapping transition for three francium isotopes. Our approach is based on an interferometric comparison to deduce the unknown laser frequency from a secondary laser frequency-standard. |
The complete gauge-invariant set of the one-loop QED corrections to the parity-nonconserving (PNC) amplitude in cesium and francium is evaluated to all orders in $\alpha Z$ using a local form of the Dirac-Fock potential. The calculations are performed in both length and velocity gauges for the absorbed photon and the ... |
An improved algorithm to evaluate the nonrelativistic three-electron Hylleraas-Configuration Interaction (Hy-CI) kinetic energy integrals over Slater orbitals and the Hamiltonian in Hylleraas coordinates is shown. The resulting analytical expressions are general for all quantum numbers of the orbitals. |
We provide a detailed quantum treatment of the spectral characteristics and of the dynamics of nondispersive two-electron wave packets along the periodically driven, collinear frozen planet configuration of helium. These highly correlated, long-lived wave packets arise as a quantum manifestation of regular islands in ... |
Recent technological advances have enabled to isolate, control and measure the properties of a single atom, leading to the possibility to perform statistics on the behavior of single quantum systems. These experiments have enabled to check a question which was out of reach previously: Is the statistics of a repeatedly... |
We measure the temperature of ultra-cold Rb-87 gases transferred into an optical lattice and compare to non-interacting thermodynamics for a combined lattice--parabolic potential. Absolute temperature is determined at low temperature by fitting quasimomentum distributions obtained using bandmapping, i.e., turning off ... |
The evolution of pionium, the $\pi^+ \pi^-$ hydrogen-like atom, while passing through matter is solved within the density matrix formalism in the first Born approximation. We compare the influence on the pionium break-up probability between the standard probabilistic calculations and the more precise picture of the de... |
We analyze the electronic structure of atoms in the first, second and third periods using the electronic kinetic energy density and stress tensor density, which are local quantities motivated by quantum field theoretic consideration, specifically the rigged quantum electrodynamics. We compute the zero surfaces of the ... |
Recent developments in searches for dark-matter candidates with atomic clocks are reviewed. The intended audience is the atomic clock community. |
We have performed ab initio calculations of the frequency shift induced by a static electric field on the cesium clock hyperfine transition. The calculations are used to find the frequency shifts due to blackbody radiation. |
Cold atom fountain clocks provide exceptional long term stability as they increase interrogation time at the expense of a larger size. We present a compact cold atom fountain using a grating magneto-optical trap (GMOT) to laser cool and launch the atoms in a simplified optical setup. |
The Compton scattering of X-ray photons, assisted by a short intense optical laser pulse, is discussed. The differential scattering cross section reveals the interesting feature that the main Klein-Nishina line is accompanied by a series of side-lines forming a broad plateau where up to ${\cal O} (10^3)$ laser photons... |
We demonstrate a precision frequency measurement using a phase-stabilized 120-km optical fiber link over a physical distance of 50 km. The transition frequency of the 87Sr optical lattice clock at the University of Tokyo is measured to be 429228004229874.1(2.4) Hz referenced to international atomic time (TAI). |
Tests of local position invariance (LPI) made by comparing the relative redshift of atomic clocks based on different atoms have been carried out for a variety of pairs of atomic species. In most cases, several absolute frequency measurements per year are used to look for an annual signal, resulting in tests that can s... |
Testing the spatial variation of fine-structure constant $\alpha$ indicated in [Webb et al., Phys. Rev. Lett. 107, 191101 (2011)] with terrestrial laboratory atomic measurements requires at least $\dot{\alpha}/\alpha \sim 10^{-19}~\textrm{y}^{-1}$ sensitivity. We conduct a systematic search of atomic systems for such ... |
The two-time Green function method in quantum electrodynamics of high-Z few-electron atoms is described in detail. This method provides a simple procedure for deriving formulas for the energy shift of a single level and for the energies and wave functions of degenerate and quasi-degenerate states. |
It is shown that the Coulomb many-particle Hamiltonians are always factorized. This fact can be used to obtain the closed analytical formula(s) for the bound state spectra of an arbitrary many-particle Coulomb system. |
Superconducting atom chips have very significant advantages in realizing trapping structures for ultracold atoms compared to conventional atom chips. We extend these advantages further by developing the ability to dynamically tailor the superconducting trap architecture. |
We present a two particle model to explain the mechanism that stabilizes a bunch of positively charged ions in an "ion trap resonator" [Pedersen etal, Phys. Rev. Lett. 87 (2001) 055001]. The model decomposes the motion of the two ions into two mappings for the free motion in different parts of the trap and one... |
The collision between a positronium (Ps) and a muonium (Mu) is studied for the first time using the static-exchange model and considering the system as a four-center Coulomb problem in the center of mass frame. An exact analysis is made to find the s-wave elastic phase-shifts, the scattering-lengths for both singlet a... |
We study numerically the interaction between an intense circularly polarized laser field and an electron moving in a potential which has a discrete cylindrical symmetry with respect to the laser pulse propagation direction. This setup serves as a simple model, e.g., for benzene and other aromatic compounds. |
The trapping of ultracold atoms using two-colour evanescent light waves formed by propagating modes of suspended optical rib waveguides is modelled in different configurations. Reducing the anisotropy of the two-colour evanescent optical dipole potential requires two laser light components with a large frequency diffe... |
We experimentally demonstrate nanoscopic transmission microscopy relying on a deterministic single particle source. This increases the signal-to-noise ratio with respect to conventional microscopy methods, which employ Poissonian particle sources. |
The accuracy of dielectronic recombination (DR) data for astrophysics related ions plays a key role in astrophysical plasma modeling. The measurement of the absolute DR rate coefficient of Fe17+ ions was performed at the main cooler storage ring at Institute of Modern Physics, Lanzhou, China. |
The electronic energy level structure of yttrium monoxide (YO) provides long-lived excited $^{2}\Delta$ states ideal for high-precision molecular spectroscopy, narrowline laser cooling at the single photon-recoil limit, and studying dipolar physics with unprecedented interaction strength. We use ultracold laser-cooled... |
We develop a versatile theoretical approach to the study of cold-atom diffractive scattering from light-field gratings by combining calculations of the optical near-field, generated by evanescent waves close to the surface of periodic nanostructured arrays, together with advanced atom wavepacket propagation on this opt... |
Comparisons of experimental data with numerical predictions of a classical model indicate that an excited hydrogen atom in a pulsed microwave electric field exhibits a nonclassical increase of stability over a relatively wide range of frequencies. I show here that this is due to selective population of long-lived "... |
Magic wavelengthsfor the $7S_{1/2}-7P_{1/2,3/2}$ transitions in Fr were reported by Dammalapati \textit{et al. } in [Phys. Rev. A 93, 043407 (2016)]. |
We have developed an efficient tabulation scheme to evaluate $6j$ symbol for atomic calculations. The scheme is appropriate for coupled-cluster based calculations. |
At low magnetic field, metastability exchange optical pumping of helium-3 is known to provide high nuclear polarizations for pressures around 1 mbar. In a recent paper, we demonstrated that operating at 1.5 T can significantly improve the results of metastability exchange optical pumping at high pressures. |
We investigate the gauge invariance of the leading logarithmic radiative correction to the two-photon decay width in hydrogenlike atoms. It is shown that an effective treatment of the correction using a Lamb-shift "potential" leads to equivalent results in both the length as well as the velocity gauges provide... |
The vibrational branching ratios from the lowest excited electronic state for $\textrm{SrOCH}_3$, $\textrm{SrNH}_2$, and $\textrm{SrSH}$ are measured at the $< 0.1\%$ level. Spectra are obtained by driving the $\tilde{X} - \tilde{A}$ transitions and dispersing the fluorescence on a grating spectrometer. |
Coherent interactions between electromagnetic and matter waves lie at the heart of quantum science and technology. However, the diffraction nature of light has limited the scalability of many atom-light based quantum systems. |
We present a new scheme for measuring the differential phase in dual atom interferometers. The magnetic field is modulated in one interferometer, and the differential phase can be extracted without measuring the amplitude of the magnetic field by combining the ellipse and linear fitting methods. |
We report on the integration of small-scale optical components into silicon wafers for use in atom chips. We present an on-chip fibre-optic atom detection scheme that can probe clouds with small atom numbers. |
A long-standing problem of fine-structure anomalies in muonic atoms is revisited by considering the $\Delta 2p$ splitting in muonic $^{90}\mathrm{Zr}$, $^{120}\mathrm{Sn}$ and $^{208}\mathrm{Pb}$ and the $\Delta 3p$ splitting in muonic $^{208}\mathrm{Pb}$. State-of-the-art techniques from both nuclear and atomic physi... |
A new geometry to trap neutral particles with an ac electric field using a simple electrodes structure is described. In this geometry, all electrodes are placed on a single chip plane, while particles are levitated above the chip. |
The phenomenon of photonic band gaps in one-dimensional optical lattices is reviewed using a microscopic approach. Formally equivalent to the transfer matrix approach in the thermodynamic limit, a microscopic model is required to study finite-size effects, such as deviations from the Bragg condition. |
TThe effects of alloying elements on diffusion pathways and migration energies of interstitial carbon in austenite (f.c.c.) and ferrite (b.c.c.) are studied using density functional theory first-principles calculations. The binding energies between carbon and alloying elements are determined through 6th nearest-neighb... |
Atomic fountain clocks launch laser-cooled balls of atoms upwards to some height $h$ in the local gravitational field where they experience both second-order Doppler shifts and gravitational frequency shifts. It is shown in this paper that the net shift, relative to a reference at the launch point, is $ g h/3 c^2$. |
We report the value of the electric quadrupole moment of $^{209}$Bi extracted from the atomic data. For this, we performed electronic structure calculations for the ground $^4S^o_{3/2}$ and excited $^2P^o_{3/2}$ states of atomic Bi using the Dirac-Coulomb-Breit Hamiltonian and the Fock space coupled cluster method wit... |
Ethylene glycol in its ground conformation has tunneling transition with the frequency about 7 GHz. This leads to a rather complicated tunneling-rotational spectrum. |
We present a low Size, Weight and Power (SWaP), low-complexity, ytterbium magneto-optical trap (MOT). We demonstrate trapping of $1.4 \times 10^6$ $^{171}$Yb atoms on the $|{^1S_0}, F = 1/2\rangle \leftrightarrow |{^1P_1}, F' = 3/2\rangle$ transition directly from a hot thermal beam. |
We report the optical imaging of a single atom with nanometer resolution using an adaptive optical alignment technique that is applicable to general optical microscopy. By decomposing the image of a single laser-cooled atom, we identify and correct optical aberrations in the system and realize an atomic position sensi... |
Fully relativistic calculations have been performed for two multiplets, $3s3p^2\;^4P$ and $3s3p4s\;^4P^o$, in Al I. Wave functions were obtained for all levels of these multiplets using the GRASP programs. Reported are the E1 transitions rates for all transitions between levels of these multiplets. |
We demonstrate a hybrid accelerometer that benefits from the advantages of both conventional and atomic sensors in terms of bandwidth (DC to 430 Hz) and long term stability. First, the use of a real time correction of the atom interferometer phase by the signal from the classical accelerometer enables to run it at bes... |
We propose a new kind of toroidal trap, designed for ultracold atoms. It relies on a combination of a magnetic trap for rf-dressed atoms, which creates a bubble-like trap, and a standing wave of light. |
We have performed ab initio mixed-states and sum-over-states calculations of parity nonconserving (PNC) electric dipole (E1) transition amplitudes between s-d electron states of Cs, Fr, Ba II, and Ra II. For the lower states of these atoms we have also calculated energies, E1 transition amplitudes, and lifetimes. |
Measuring the delay for an electron to emerge from different states is one of the major achievements of attosecond science. This delay can have two origins - the electron wave packet is reshaped during departure by the electrostatic field of the ionizing medium or it is modified by dynamic interaction with the remaini... |
We have used laser ablation and helium buffer-gas cooling to produce the titanium-helium van der Waals molecule at cryogenic temperatures. The molecules were detected through laser-induced fluorescence spectroscopy. |
We have demonstrated the possibility for a compact frequency standard based on a sample of cold cesium atoms. In a cylindrical microwave cavity, the atoms are cooled and interrogated during a free expansion and then detected. |
A new approach, called Adaptive Q-control, for tapping-mode Atomic Force Microscopy (AFM) is introduced and implemented on a home-made AFM set-up utilizing a Laser Doppler Vibrometer (LDV) and a piezo-actuated bimorph probe. In the standard Q-control, the effective Q-factor of the scanning probe is adjusted prior to t... |
We have successfully loaded a magneto-optic trap for Yb atoms from a thermal source without the use of a Zeeman slower. The source is placed close to the trapping region so that it provides a large flux of atoms that can be cooled and captured. |
Positronium-hydrogen (Ps-H) scattering is of interest, as it is a fundamental four-body Coulomb problem. We have investigated low-energy Ps-H scattering below the Ps(n=2) excitation threshold using the Kohn variational method and variants of the method with a trial wavefunction that includes highly correlated Hylleraa... |
Ultracold collisions of neutral atoms and molecules have been of great interest since experimental advances enabled the cooling and trapping of such species. This study is a theoretical investigation of a low-energy collision between an alkali atom and a diatomic molecule, accompanied by absorption of a photon from an... |
Mobile gravimetry is important in metrology, navigation, geodesy, and geophysics. Atomic gravimeters could be among the most accurate mobile gravimeters, but are currently constrained by being complex and fragile. |
We have measured the ground-state $g$-factor of boronlike argon $^{40}\textrm{Ar}^{13+}$ with a fractional uncertainty of \SI{1.4e-9}{} with a single ion in the newly developed ALPHATRAP double Penning-trap setup. The here obtained value of $g=0.663\,648\,455\,32(93)$ is in agreement with our theoretical prediction of... |
Exploring quantum phenomena in a curved spacetime is an emerging interdisciplinary area relating many fields in physics such as general relativity, thermodynamics, and quantum information. One famous prediction is the Hawking-Unruh thermal radiation, the manifestation of Minkowski vacuum in an accelerating reference f... |
We predict a sequence of magic-zero wavelengths for the Sr excited $5s5p~ ^3P_0$ state, and provide a general roadmap for extracting transition matrix elements using precise frequency measurements. We demonstrate that such measurements can serve as a best global benchmark of the spectroscopic accuracy that is required... |
Bosonic dimer-dimer scattering is studied near the unitary limit using momentum-space equations for the four-particle transition operators. The impact of the Efimov effect on the dimer-dimer scattering observables is explored and a number of universal relations is established with high accuracy. |
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