Atomic Physics

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The effect of hyperfine splitting on Stark broadening for three blue-green Cu I lines in laser-induced plasma (1907.02920v1)

Andrey M. Popov, Nikolay I. Sushkov, Sergey M. Zaytsev, Timur A. Labutin

2019-07-05

Stark effect is observed in many natural and artificial plasmas and is of great importance for diagnostic purposes. Since this effect alters profiles of spectral lines, it should be taken into account when assessing chemical composition of radiation sources, including stars. Copper is one of the elements which studies of stellar atmospheres deal with. To this end, UV and visible Cu lines are used. However, there is a lack of agreement between existing data on their Stark parameters. It is therefore of interest to obtain new experimental data on these lines and to compare them to previous results. In this work, we have estimated Stark widths and shifts for three blue-green lines at 5105.54, 5153.24, and 5218.20 A (corresponding transitions are [3d104p] 2P{\deg} - [3d94s2] 2D and [3d104d] 2D - [3d104p] 2P{\deg}) observed in a "long-spark" laser-induced plasma. For the first time, we have accurately estimated an impact of hyperfine splitting on the profile shapes of the studied lines taking also into account the isotope shifts. We have shown that both effects considerably influence shift and width of Cu I line at 5105.54 A, and shifts of Cu I lines at 5153.24 and 5218.20 A.

Collective Mode Interferences in Light--Matter Interactions (1808.08415v3)

Robert J. Bettles, Teodora Ilieva, Hannes Busche, Paul Huillery, Simon W. Ball, Nicholas L. R. Spong, Charles S. Adams

2018-08-25

We present a theoretical and experimental analysis of transient optical properties of a dense cold atomic gas. After the rapid extinction of a weak coherent driving field (mean photon number ), a transient flash' is observed. Surprisingly the decay of theflash' is faster than the decay of the fastest superradiant mode of the system. We show that this `faster than superradiance decay' is expected due to the interference between collective eigenmodes that exhibit a range of frequency shifts away from the bare atomic transition. Experimental results confirm that the initial decay rate of the superradiant flash increases with optical depth, in agreement with the numerical simulations for the experimental conditions.

The quantum Talbot effect for a chain of partially correlated Bose-Einstein condensates (1907.02833v1)

V. B. Makhalov, A. V. Turlapov

2019-07-05

The matter-wave interference picture, which appears within the quantum Talbot effect, changes qualitatively in response to even a small randomness in the phases of the sources. The spatial spectrum acquires peaks which are absent in the case of equal phases. The mathematic model of the effect is presented. The manifestations of the phase randomness in experiments with atomic and molecular Bose condensates, is discussed. Thermometry based on observable consequences of phase randomness is proposed.

Continuous guided strontium beam with high phase-space density (1907.02793v1)

Chun-Chia Chen, Shayne Bennetts, Rodrigo González Escudero, Benjamin Pasquiou, Florian Schreck

2019-07-05

A continuous guided atomic beam of with a phase-space density exceeding in the moving frame and a flux of is demonstrated. This phase-space density is around three orders of magnitude higher than previously reported for steady-state atomic beams. We detail the architecture necessary to produce this ultracold atom source and characterize its output after of propagation. With radial temperatures of less than and a velocity of this source is ideal for a range of applications. For example, it could be used to replenish the gain medium of an active optical superradiant clock or be employed to overcome the Dick effect that can limit the performance of pulsed-mode atom interferometers, atomic clocks and ultracold atom based sensors in general. Finally, this result represents a significant step towards the development of a steady-state atom laser.

Precision measurement of the ionization energy and quantum defects of 39K I (1907.02776v1)

Michael Peper, Felix Helmrich, Jonas Butscher, Josef Anton Agner, Hansjürg Schmutz, Frédéric Merkt, Johannes Deiglmayr

2019-07-05

We present absolute-frequency measurements in ultracold 39K samples of the transitions from the ground state to np Rydberg states. A global nonlinear regression of the np1/2 and np3/2 term values yields an improved wave number of 35009.8139710(22)(sys)(3)(stat) cm-1 for the first ionization threshold of 39K and the quantum defects of the np1/2 and np3/2 series. In addition, we report the frequencies of selected one-photon transitions n's <- np3/2, n'd <- np3/2, n'f <- nd and n'g <- nf and two-photon transitions nf <- np determined by millimeter-wave spectroscopy. By combining the results from the laser and millimeter-wave spectroscopic experiments, we obtain improved values for the quantum defects of the s1/2, d3/2, d5/2, f and g states. For the d series, the inverted fine structure was confirmed for n >= 32. The fine-structure splitting of the f series is less than 100 kHz at n=31, significantly smaller than the hydrogenic splitting, and the fine structure of the g series is regular for n >= 30, with a fine-structure splitting compatible with the hydrogenic prediction. From the measured quantum defects of the f and g series we derive an estimate for the static dipole and quadrupole polarizabilities of the K+ ion core. Additionally, the hyperfine splitting of the 4s1/2 ground state of 39K was determined to be 461.719700(5) MHz using radio-frequency spectroscopy and Ramsey-type interferometry.

Fourier transform spectroscopy, relativistic electronic structure calculation, and coupled-channel deperturbation analysis of the fully mixed and states of Cs (1907.02716v1)

A. Znotins, A. Kruzins, M. Tamanis, R. Ferber, E. A. Pazyuk, A. V. Stolyarov, A. Zaitsevskii

2019-07-05

The 4503 rovibronic term values belonging to the mutually perturbed and states of Cs were extracted from laser induced fluorescence (LIF) Fourier transform spectra with the 0.01 cm uncertainty. The experimental term values of the complex covering the rotational levels in the excitation energy range cm were involved into coupled-channel (CC) deperturbation analysis. The deperturbation model takes explicitly into account spin-orbit coupling of the and states as well as spin-rotational interaction between the , and components of the state. The \emph{ab initio} relativistic calculations on the low-lying electronic states of Cs were accomplished in the framework of Fock space relativistic coupled cluster (FSRCC) approach to provide the interatomic potentials of the interacting and states as well as the relevant spin-orbit coupling function. To validate the present CC deperturbation analysis solely obtained by energy-based data, the LIF intensity distributions were measured and compared with their theoretical counterparts obtained by means of the non-adiabatic vibrational wave functions of the complex and the FSRCC transition dipole moments calculated by the finite-field method.

Spectral control over -ray echo using a nuclear frequency comb system (1907.02672v1)

Chia-Jung Yeh, Po-Han Lin, Xiwen Zhang, Olga Kocharovskaya, Wen-Te Liao

2019-07-05

Two kinds of spectral control over -ray echo using a nuclear frequency comb system are theoretically investigated. A nuclear frequency comb system is composed of multiple nuclear targets under magnetization (hyperfine splitting), mechanical motion (Doppler shift) or both, namely, moving and magnetized targets. In frequency domain the unperturbed single absorption line of -ray therefore splits into multiple lines with equal spacing and becomes a nuclear frequency comb structure. We introduce spectral shaping and dynamical splitting to the frequency comb structure respectively to optimize the use of a medium and to break the theoretical maximum of echo efficiency, i.e., 54%. Spectral shaping scheme leads to the reduction of required sample resonant thickness for achieving high echo efficiency of especially a broadband input. Dynamical splitting method significantly advances the echo efficiency up to 67% revealed by two equivalent nuclear frequency comb systems. We also show that using only few targets is enough to obtain good echo performance, which significantly eases the complexity of implementation. Our results extend quantum optics to 10keV regime and lay the foundation of the development of -ray memory.

Search for transient variations of the fine structure constant and dark matter using fiber-linked optical atomic clocks (1907.02661v1)

B. M. Roberts, P. Delva, A. Al-Masoudi, A. Amy-Klein, C. Bærentsen, C. F. A. Baynham, E. Benkler, S. Bilicki, W. Bowden, E. Cantin, E. A. Curtis, S. Dörscher, F. Frank, P. Gill, R. M. Godun, G. Grosche, A. Hees, I. R. Hill, R. Hobson, N. Huntemann, J. Kronjäger, S. Koke, A. Kuhl, R. Lange, T. Legero, B. Lipphardt, C. Lisdat, J. Lodewyck, O. Lopez, H. S. Margolis, H. Álvarez-Martínez, F. Meynadier, F. Ozimek, E. Peik, P. -E. Pottie, N. Quintin, R. Schwarz, C. Sanner, M. Schioppo, A. Silva, U. Sterr, Chr. Tamm, R. LeTargat, P. Tuckey, G. Vallet, T. Waterholter, D. Xu, P. Wolf

2019-07-05

We search for transient variations of the fine structure constant using data from a European network of fiber-linked optical atomic clocks. By searching for coherent variations in the recorded clock frequency comparisons across the network, we significantly improve the constraints on transient variations of the fine structure constant. For example, we constrain the variation in alpha to <5*10^-17 for transients of duration 10^3 s. This analysis also presents a possibility to search for dark matter, the mysterious substance hypothesised to explain galaxy dynamics and other astrophysical phenomena that is thought to dominate the matter density of the universe. At the current sensitivity level, we find no evidence for dark matter in the form of topological defects (or, more generally, any macroscopic objects), and we thus place constraints on certain potential couplings between the dark matter and standard model particles, substantially improving upon the existing constraints, particularly for large (>~10^4 km) objects.

Correlation trends in the hyperfine structure for Rb, Cs, Fr and high-accuracy predictions for hyperfine constants (1907.02657v1)

S. J. Grunefeld, B. M. Roberts, J. S. M. Ginges

2019-07-05

We have performed high-precision calculations of the hyperfine structure for n 2S_1/2 and n 2P_1/2 states of the alkali-metal atoms Rb, Cs, and Fr across principal quantum number n, and studied the trend in the size of the correlations. Our calculations were performed in the all-orders correlation potential method. We demonstrate that the relative correlation corrections fall off quickly with n and tend towards constant and non-zero values for highly-excited states. This trend is supported by experiment, and we utilize the smooth dependence on n to make high-accuracy predictions of the hyperfine constants, with uncertainties to within 0.1% for most states of Rb and Cs.

Sideband cooling of the radial modes of motion of a single ion in a Penning trap (1907.02406v1)

P. Hrmo, M. K. Joshi, V. Jarlaud, O. Corfield, R. C. Thompson

2019-07-04

Doppler and sideband cooling are long standing techniques that have been used together to prepare trapped atomic ions in their ground state of motion. In this paper we study how these techniques can be extended to cool both radial modes of motion of a single ion in a Penning trap. We numerically explore the prerequisite experimental parameters for efficient Doppler cooling in the presence of an additional oscillating electric field to resonantly couple the radial modes. The simulations are supported by experimental data for a single Ca ion Doppler cooled to 100 phonons in both modes at a magnetron frequency of 52 kHz and a modified cyclotron frequency of 677 kHz. For these frequencies, we then show that mean phonon numbers of for the modified cyclotron and for the magnetron motions are achieved after 68 ms of sideband cooling.

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