Atomic Physics

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Single-beam Zeeman slower and magneto-optical trap using a nanofabricated grating (1811.09180v3)

D. S. Barker, E. B. Norrgard, N. N. Klimov, J. A. Fedchak, J. Scherschligt, S. Eckel

2018-11-22

We demonstrate a compact (0.25 L) system for laser cooling and trapping atoms from a heated dispenser source. Our system uses a nanofabricated diffraction grating to generate a magneto-optical trap (MOT) using a single input laser beam. An aperture in the grating allows atoms from the dispenser to be loaded from behind the chip, increasing the interaction distance of atoms with the cooling light. To take full advantage of this increased distance, we extend the magnetic field gradient of the MOT to create a Zeeman slower. The MOT traps approximately Li atoms emitted from an effusive source with loading rates in excess of s. Our design is portable to a variety of atomic and molecular species and could be a principal component of miniaturized cold-atom-based technologies.

Atomic Resonant Single-Mode Squeezed Light from Four-Wave Mixing through Feedforward (1906.07666v1)

Saesun Kim, Alberto M. Marino

2019-06-18

Squeezed states of light have received renewed attention due to their applicability to quantum-enhanced sensing. To take full advantage of their reduced noise properties to enhance atomic-based sensors, it is necessary to generate narrowband near or on atomic resonance single-mode squeezed states of light. We have previously generated bright two-mode squeezed states of light, or twin beams, that can be tuned to resonance with the D1 line of Rb with a non-degenerate four-wave mixing (FWM) process in a double-lambda configuration in a Rb vapor cell. Here we report on the use of feedforward to transfer the amplitude quantum correlations present in the twin beams to a single beam for the generation of single-mode amplitude squeezed light. With this technique we obtain a single-mode squeezed state with a squeezing level of dB when it is tuned off-resonance and a level of dB when it is tuned on resonance with the D1 to transition of Rb.

Floquet engineering of optical lattices with spatial features and periodicity below the diffraction limit (1906.07646v1)

S. Subhankar, P. Bienias, P. Titum, T-C. Tsui, Y. Wang, A. V. Gorshkov, S. L. Rolston, J. V. Porto

2019-06-18

Floquet engineering or coherent time periodic driving of quantum systems has been successfully used to synthesize Hamiltonians with novel properties. In ultracold atomic systems, this has led to experimental realizations of artificial gauge fields, topological band structures, and observation of dynamical localization, to name just a few. Here we present a Floquet-based framework to stroboscopically engineer Hamiltonians with spatial features and periodicity below the diffraction limit of light used to create them by time-averaging over various configurations of a 1D optical Kronig-Penney (KP) lattice. The KP potential is a lattice of narrow subwavelength barriers spaced by half the optical wavelength () and arises from the non-linear optical response of the atomic dark state. Stroboscopic control over the strength and position of this lattice requires time-dependent adiabatic manipulation of the dark state spin composition. We investigate adiabaticity requirements and shape our time-dependent light fields to respect the requirements. We apply this framework to show that a -spaced lattice can be synthesized using realistic experimental parameters as an example, discuss mechanisms that limit lifetimes in these lattices, explore candidate systems and their limitations, and treat adiabatic loading into the ground band of these lattices.

Quantum phases of tilted dipolar bosons in two-dimensional optical lattice (1906.07483v1)

Soumik Bandyopadhyay, Rukmani Bai, Sukla Pal, K. Suthar, Rejish Nath, D. Angom

2019-06-18

We consider a minimal model to describe the quantum phases of ultracold dipolar bosons in two-dimensional (2D) square optical lattices. The model is a variation of the extended Bose-Hubbard model and apt to study the quantum phases arising from the variation in the tilt angle of the dipolar bosons. At low tilt angles , the ground state of the system are phases with checkerboard order, which could be either checkerboard supersolid or checkerboard density wave. For high tilt angles , phases with striped order of supersolid or density wave are preferred. In the intermediate domain an emulsion or SF phase intervenes the transition between the checkerboard and striped phases. The attractive interaction dominates for , which renders the system unstable and there is a density collapse. For our studies we use Gutzwiller mean-field theory to obtain the quantum phases and the phase boundaries. In addition, we calculate the phase boundaries between an incompressible and a compressible phase of the system by considering second order perturbation analysis of the mean-field theory. The analytical results, where applicable, are in excellent agreement with the numerical results.

Reduction of frequency-dependent light shifts in light-narrowing regimes: A study using effective master equations (1811.01445v3)

Yue Chang, Yu-Hao Guo, Jie Qin

2018-11-04

Alkali-metal-vapor magnetometers, using coherent precession of polarized atomic spins for magnetic field measurement, have become one of the most sensitive magnetic field detectors. Their application areas range from practical uses such as detections of NMR signals to fundamental physics research such as searches for permanent electric dipole moments. One of the main noise sources of atomic magnetometers comes from the light shift that depends on the frequency of the pump laser. In this work, we theoretically study the light shift, taking into account the relaxation due to the optical pumping and the collision between alkali atoms and between alkali atoms and the buffer gas. Starting from a full master equation containing both the ground and excited states, we adiabatically eliminate the excited states and obtain an effective master equation in the ground-state subspace that shows an intuitive picture and dramatically accelerates the numerical simulation. Solving this effective master equation, we find that in the light-narrowing regime, where the line width is reduced while the coherent precession signal is enhanced, the frequency-dependence of the light shift is largely reduced, which agrees with experimental observations in cesium magnetometers. Since this effective master equation is general and is easily solved, it can be applied to an extensive parameter regime, and also to study other physical problems in alkali-metal-vapor magnetometers, such as heading errors.

An electrostatic in-line charge-state purification system for multicharged ions in the kiloelectronvolt energy range (1906.07428v1)

Daniel Schury, Ajit Kumar, Alain Méry, Jean-Yves Chesnel, Anna Lévy, Stéphane Macé, Christophe Prigent, Jean-Marc Ramillon, Jimmy Rangama, Patrick Rousseau, Sébastien Steydli, Martino Trassinelli, Dominique Vernhet, Emily Lamour

2019-06-18

The performance of a newly built omega type electrostatic analyzer designed to act as an in-line charge state purification system for ions in the keV energy range is reported. The analyzer consists of a set of four consecutive electrostatic 140{\deg} concentric cylindrical electrodes enclosed by Matsuda electrodes. This setup was recently tested and validated using , and ion beams at an energy of 14 qkeV at the ARIBE facility. A resolving power of 10.5 and a transmission of 100 % of the desired charge state are measured allowing a good purification of incoming ion beams with charge states up to 10+ and a fairly good purification for charge states at least up to 20+. In comparison with other in-line solutions such as Wien filter, our system has the advantage of being purely electrostatic and therefore lacking common drawbacks as for example hysteresis.

Possibility of forming a stable Bose-Einstein condensate of positronium atoms (1903.08353v2)

Y. Zhang, M. -S. Wu, J. -Y. Zhang, Y. Qian, X. Gao, K. Varga

2019-03-20

The confined variational method in conjunction with the orthogonalizing pseudo-potential method and the stabilization method is used to study the low energy elastic scattering between two spin-polarized metastable positronium Ps(2,) atoms. Explicitly correlated Gaussian basis functions are adopted to properly describe the complicated Coulomb interaction among the four charged particles. The calculated -wave scattering length () is positive, indicating the possibility of forming a stable Bose-Einstein condensate of fully spin-polarized atoms. Our results will open a new way of experimental realization of Ps condensate and development of -ray and atom lasers.

Doppler-free saturation of the cascade fluorescence that follows excitation of the transition in atomic rubidium (1906.07114v1)

J. E. Navarro-Navarrete, A. Díaz-Calderón, L. M. Hoyos-Campo, F. Ponciano-Ojeda, J. Flores-Mijangos, F. Ramírez-Martínez, J. Jiménez-Mier

2019-06-17

We present an experimental scheme that produces Doppler-free spectra of the second resonance transition in atomic rubidium. The experiment uses the saturation of the cascade fluorescence that occurs when thermal rubidium atoms interact with two counterpropagating nm laser beams of comparable intensity. Part of the excited atomic population goes through the level which then decays by emission of nm photons. Narrow dips appear in this otherwise broad nm fluorescence, which allows resolution of the hyperfine structure. A rate equation model is used to interpret the spectra. It is also shown that these narrow peaks can be used to lock the frequency of the nm laser. Using a second beam modulated in frequency produces three sets of spectra with known frequency spacings that can be used to perform an all-optical measurement of the hyperfine splittings of the manifold in rubidium.

Tracking Attosecond Electronic Coherences using Phase-Manipulated Extreme Ultraviolet Pulses (1906.07112v1)

Andreas Wituschek, Lukas Bruder, Enrico Allaria, Ulrich Bangert, Marcel Binz, Carlo Callegari, Giulio Cerullo, Paolo Cinquegrana, Luca Gianessi, Miltcho Danailov, Alexander Demidovich, Michele Di Fraia, Marcel Drabbels, Raimund Feifel, Tim Laarmann, Rupert Michiels, Najmeh Sadat Mirian, Marcel Mudrich, Ivaylo Nikolov, Finn H. O'Shea, Giuseppe Penco, Paolo Piseri, Oksana Plekan, Kevin Charles Prince, Andreas Przystawik, Primož Rebernik Ribič, Giuseppe Sansone, Paolo Sigalotti, Simone Spampinati, Carlo Spezzani, Richard James Squibb, Stefano Stranges, Daniel Uhl, Frank Stienkemeier

2019-06-17

The recent development of novel extreme ultraviolet (XUV) coherent light sources bears great potential for a better understanding of the structure and dynamics of matter. Promising routes are advanced coherent control and nonlinear spectroscopy schemes in the XUV energy range, yielding unprecedented spatial and temporal resolution. However, their implementation has been hampered by the experimental challenge of generating XUV pulse sequences with precisely controlled timing and phase properties. In particular, direct control and manipulation of the phase of individual pulses within a XUV pulse sequence opens exciting new possibilities for coherent control and multidimensional spectroscopy schemes, but has not been accomplished. Here, we overcome these constraints in a highly time-stabilized and phase-modulated XUV-pump, XUV-probe experiment which directly probes the evolution and dephasing of an inner subshell electronic coherence. This new approach, avoiding any XUV optics for direct pulse manipulation, opens up extensive applications of advanced nonlinear optics and spectroscopy at XUV wavelengths.

Nonlinear magneto-optical rotation with parametric resonance (1906.07082v1)

Piotr Put, Piotr Wcisło, Wojciech Gawlik, Szymon Pustelny

2019-06-17

We report on investigations of nonlinear magneto-optical rotation (NMOR) in rubidium vapor subjected to a modulated magnetic field and continuous-wave (CW) laser-light illumination. By superimposing modulation and a static (DC) magnetic fields, we demonstrate the appearance of resonances at both small and large (compared to the ground-state relaxation rate) values of the static field. Since in conventional NMOR, there is no rotation at high fields, this suggests an existence of a novel mechanism generating anisotropy in the considered case, which we identify as parametric resonance. The experiments are performed using light of small ellipticity and rotation signals are significantly enhanced by combining atom-induced polarization rotation with a passive rotation induced with a wave plate. All the experimental observations are supported with theoretical simulations. The density-matrix formalism and angular-momentum probability surfaces are used to provide intuitive explanation of the observed signals.

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