Atomic Physics
Non-adiabatic molecular association in thermal gases driven by radio-frequency pulses (1903.01389v1)
P. Giannakeas, L. Khaykovich, Jan-Michael Rost, Chris H. Greene
2019-03-04
The molecular association process in a thermal gas of
Rb is investigated where the effects of the envelope of the radio-frequency field are taken into account. For experimentally relevant parameters our analysis shows that with increasing pulse length the corresponding molecular conversion efficiency exhibits low-frequency interference fringes which are robust under thermal averaging over a wide range of temperatures. This dynamical interference phenomenon is attributed to St"uckelberg phase accumulation between the low-energy continuum states and the dressed molecular state which exhibits a shift proportional to the envelope of the radio-frequency pulse intensity.
Interactions of benzene, naphthalene, and azulene with alkali-metal and alkaline-earth-metal atoms for ultracold studies (1903.01378v1)
Paweł Wójcik, Tatiana Korona, Michał Tomza
2019-03-04
We consider collisional studies of polyatomic aromatic hydrocarbon molecules immersed into ultracold atomic gases and investigate intermolecular interactions of exemplary benzene, naphthalene, and azulene with alkali-metal (Li, Na, K, Rb, Cs) and alkaline-earth-metal (Mg, Ca, Sr, Ba) atoms. We apply the state-of-the-art ab initio techniques to compute the potential energy surfaces (PESs). We use the coupled cluster method restricted to single, double, and noniterative triple excitations to reproduce the correlation energy and the small-core energy-consistent pseudopotentials to model the scalar relativistic effects in heavier metal atoms. We also report the leading long-range isotropic and anisotropic dispersion and induction interaction coefficients. The PESs are characterized in detail and the nature of intermolecular interactions is analyzed and benchmarked using symmetry-adapted perturbation theory. The full three-dimensional PESs are provided for selected systems within the atom-bond pairwise additive representation and can be employed in scattering calculations. Presented study of the electronic structure is the first step towards the evaluation of prospects for sympathetic cooling of polyatomic aromatic molecules with ultracold atoms. We suggest azulene, an isomer of naphthalene which possesses a significant permanent electric dipole moment and optical transitions in the visible range, as a promising candidate for electric field manipulation and buffer-gas or sympathetic cooling.
Ultra-high-speed Terahertz Imaging Using Atomic Vapour (1903.01308v1)
Lucy A. Downes, Andrew R. MacKellar, Daniel J. Whiting, Cyril Bourgenot, Charles S. Adams, Kevin J. Weatherill
2019-03-04
Terahertz (THz) technologies, generally defined as operating in the 0.1-10THz range, bridge the gap between electronic and photonic devices. Because THz radiation passes readily through materials such as plastics, paper and cloth it can be employed in non-destructive testing, and as it is non-ionising it is considered safe for security and biomedical applications. There is significant demand for high speed THz imaging across a range of applications but, despite ongoing efforts, fast full-field imaging remains an unfulfilled goal. Here we demonstrate a THz imaging system based upon efficient THz-to-optical conversion in atomic vapour, where full-field images can be collected at ultra-high speeds using conventional optical camera technology. For a 0.55 THz field we show an effective 1 cm
sensor with near diffraction-limited spatial resolution and a minimum detectable power of 190
30 fW s
per 40x40
m pixel capable of video capture at 3000 frames per second. This combination of speed and sensitivity represents a step change in the state of the art of THz imaging, and will likely lead to its uptake in wider industrial settings. With further improvements we expect that even higher frame rates of up to 1 MHz would be possible.
Spatially-selective in situ magnetometry of ultracold atomic clouds (1811.01798v2)
Ottó Elíasson, Robert Heck, Jens S. Laustsen, Mario Napolitano, Romain Müller, Mark G. Bason, Jan J. Arlt, Jacob F. Sherson
2018-11-05
We demonstrate novel implementations of high-precision optical magnetometers which allow for spatially-selective and spatially-resolved in situ measurements using cold atomic clouds. These are realised by using shaped dispersive probe beams combined with spatially-resolved balanced homodyne detection. Two magnetometer sequences are discussed: a vectorial magnetometer, which yields sensitivities two orders of magnitude better compared to a previous realisation and a Larmor magnetometer capable of measuring absolute magnetic fields. We characterise the dependence of single-shot precision on the size of the analysed region for the vectorial magnetometer and provide a lower bound for the measurement precision of magnetic field gradients for the Larmor magnetometer. Finally, we give an outlook on how dynamic trapping potentials combined with selective probing can be used to realise enhanced quantum simulations in quantum gas microscopes.
A Multiple-Band Rydberg-Atom Based Receiver/Antenna: AM/FM Stereo Reception (1903.00786v1)
Christopher L. Holloway, Matthew T. Simons, Abdulaziz H. Haddab, Joshua A. Gordon, Stephen D. Voran
2019-03-02
With the re-definition of the International System of Units (SI) that occurred in October of 2018, there has recently been a great deal of attention on the development of atom-based sensors for metrology applications. In particular, great progress has been made in using Rydberg-atom based techniques for electric (E) field metrology. These Rydberg-atom based E-field sensors have made it possible to develop atom-based receivers and antennas, which potentially have many benefits over conventional technologies in detecting and receiving modulated signals. In this paper, we demonstrate the ``first'' multi-channel atom-based reception of both amplitude (AM) and frequency (FM) modulation signals. We demonstrate this by using two different atomic species in order to detect and receive AM and FM modulated signals in stereo. Also, in this paper we investigate the effect of Gaussian noise on the ability to receive AM/FM signals. These results illustrate the multi-band (or multi-channel) receiving capability of a atom-based receiver/antenna to produce high fidelity stereo reception from both AM and FM signals. This paper shows an interesting way of applying the relatively newer (and something esoteric) field of quantum-optics and atomic-physics to the century old topic of radio reception.
Sub-cycle Electron Dynamics in the Generation of Below Threshold Harmonics (1903.00664v1)
Li Wang, Jinxing Xue, Zhinan Zeng, Ruxin Li, Zhizhan Xu
2019-03-02
The generation of the below threshold harmonics (BTHs) under different driving laser intensities is investigated. The linearly shifting of photon energy and resonantly enhancement of photon yield of the harmonics from 23rd (H23) to 27th (H27) are found by changing the laser intensity around 18.6 TW/cm2. It is identified that this driving laser intensity dependence is due to the transient ac Stark-shifted resonance between the first excited state and the ground state. With this transient ac Stark, the linearly shifting of the photon energy can be interpreted very well by considering the sub-cycle electron dynamics for BTH generation, which shows that the generation of the BTHs is surprisingly similar to the plateau harmonics.
Three-dimensional modeling magneto-optical trapping of MgF molecule with multilevel rate equations (1903.00609v1)
Supeng Xu, Meng Xia, Ruoxi Gu, Yanning Yin, Liang Xu, Yong Xia, Jianping Yin
2019-03-02
We present a theoretical study of magneto-optical trapping (MOT) force exerted on magnesium monofluoride (MgF) with 3D rate equations, in which we have considered the complex vibrational and rotational levels and the effects of small internal splittings and degeneracies,including fine and hyperfine structures and the magnetic quantum numbers. We investigate the feasibility of MOT for MgF with a very small excited state g-factor (
) and a large radiative decay reate (
MHz) for the electronic transition of X
to A
states. We also optimize the MOT with reference to the three-, four- and more-frequency component models with various polarization configurations and detunings. By applying the dual frequency arrangement to more than one hyperfine level, we suggest a configuration of the 3+1 frequency components for achieving the MOT of MgF.
Two-photon photoassociation spectroscopy of the 
YbLi molecular ground state (1903.00603v1)
Alaina Green, Jun Hui See Toh, Richard Roy, Ming Li, Svetlana Kotochigova, Subhadeep Gupta
2019-03-02
We report on measurements of the binding energies of several weakly bound vibrational states of the paramagnetic
Yb
Li molecule in the electronic ground state using two-photon spectroscopy in an ultracold atomic mixture confined in an optical dipole trap. We theoretically analyze the experimental spectrum to obtain an accurate description of the long-range potential of the ground state molecule. Based on the measured binding energies, we arrive at an improved value of the interspecies
-wave scattering length
. Employing coherent two-photon spectroscopy we also observe the creation of ''dark'' atom-molecule superposition states in the heteronuclear Yb-Li system. This work is an important step towards the efficient production of ultracold YbLi molecules via association from an ultracold atomic mixture.
Effect of laser frequency fluctuation on the decoherence rate of Rydberg polaritons (1902.09845v2)
Bongjune Kim, Ko-Tang Chen, Chia-Yu Hsu, Shih-Si Hsiao, Yu-Chih Tseng, Chin-Yuan Lee, Shih-Lun Liang, Yi-Hua Lai, Julius Ruseckas, Gediminas Juzeliunas, Ite A. Yu
2019-02-26
The effect of electromagnetically induced transparency (EIT) using Rydberg-state atoms provides high optical nonlinearity to effectively mediate the photon-photon interaction. However, the decoherence rate of Rydberg polaritons, which plays an important role in the efficiency of optical nonlinear, can be largely influenced by the laser frequency fluctuation. In this work, we carry out a systematic theoretical and experimental study of effects of the laser frequency fluctuation on the EIT. We analyze a theoretical model that quantitatively describes the relationship between the decoherence rate and laser frequency fluctuation. The derived theoretical formula was experimentally verified for the
-type EIT system of laser-cooled
Rb atoms, in which one can completely eliminate or controllably introduce the laser frequency fluctuation. We further extended the formula to include the effect of the Doppler shift due to the atomic motion, and measured the decoherence rate in the Rydberg-EIT system. The measurement was carried out using
K and with the Rydberg state of
involved. We achieved a rather low decoherence rate of
48 kHz at a moderate coupling Rabi frequency of
Reduction of light shifts in Ramsey spectroscopy with a combined error signal (1903.00566v1)
M. Shuker, J. W. Pollock, R. Boudot, V. I. Yudin, A. V. Taichenachev, J. Kitching, E. A. Donley
2019-03-01
Light-induced frequency shifts can be a key limiting contribution to the mid and long-term frequency instability in atomic clocks. In this letter, we demonstrate the experimental implementation of the combined error signal interrogation protocol to a cold-atom clock based on coherent population trapping (CPT) and Ramsey spectroscopy. The method uses a single error signal that results from the normalized combination of two error signals extracted from two Ramsey sequences of different dark periods. The single combined error signal is used to stabilize the atomic clock frequency. Compared to the standard Ramsey-CPT interrogation, this method reduces the clock frequency sensitivity to light-shift variations by more than one order of magnitude. This method can be applied in various kinds of Ramsey-based atomic clocks, sensors and instruments.
