arXiv subjects

D. S. Elliott

Publications and source records attributed to D. S. Elliott.

28 records · Page 2Linked to original sources

arXiv2016

Measurement scheme and analysis for weak ground state hyperfine transition moments through two-pathway coherent control

We report our detailed analysis of a table-top system for the measurement of the weak-force-induced electric dipole moment of a ground state hyperfine transition carried out in an atomic beam geometry. We describe an experimental configuration of conductors for application of orthogonal r.f. and static electric fields, with cavity enhancement of the r.f. field amplitude, that allows confinement of the r.f. field to a region in which the static fields are uniform and well-characterized. We carry out detailed numerical simulations of the field modes, and analyze the expected magnitude of statistical and systematic limits to the measurement of this transition amplitude in atomic cesium. The combination of an atomic beam with this configuration leads to strong suppression of magnetic dipole contributions to the atomic signal. The application of this technique to the measurement of extremely weak transition amplitudes in other atomic systems, especially alkali metals, seems very feasible.

physics.atom-ph↗

arXiv2015

Formation of ultracold $^{7}$Li$^{85}$Rb molecules in the lowest triplet electronic state by photoassociation and their detection by ionization spectroscopy

We report the formation of ultracold $^{7}$Li$^{85}$Rb molecules in the $a^{3}Σ^{+}$ electronic state by photoassociation (PA) and their detection via resonantly enhanced multiphoton ionization (REMPI). With our dual-species Li and Rb magneto-optical trap (MOT) apparatus, we detect PA resonances with binding energies up to ~62 cm$^{-1}$ below the $^{7}$Li 2s $^{2}S_{1/2}$ $+$ $^{85}$Rb 5p $^{2}P_{1/2}$ asymptote. In addition, we use REMPI spectroscopy to probe the $a^{3}Σ^{+}$ state and excited electronic $3^{3} Π$ and $4^{3} Σ^{+}$ states, and identify $a^{3}Σ^{+} (v" = 7 - 13)$, $3^{3} Π(v'_Π = 0 - 10)$ and $4^{3} Σ^{+} (v'_Σ = 0 - 5)$ vibrational levels. Our line assignments agree well with ab initio calculations. These preliminary spectroscopic studies on previously unobserved electronic states are crucial to discovering transition pathways for transferring ultracold LiRb molecules created via PA to deeply bound rovibrational levels of the electronic ground state.

physics.atom-ph↗

arXiv2014

Formation of deeply bound ultracold LiRb molecules via photoassociation near the Li 2S$_{1/2}$ + Rb 5P$_{3/2}$ asymptote

We present spectra of ultracold $^7$Li$^{85}$Rb molecules in their electronic ground state formed by spontaneous decay of weakly bound photoassociated molecules. Beginning with atoms in a dual species magneto-optical trap (MOT), weakly bound molecules are formed in the 4(1) electronic state, which corresponds to the B$^1Π$ state at short range. These molecules spontaneously decay to the electronic ground state and we use resonantly enhanced multiphoton ionization (REMPI) to determine the vibrational population distribution in the electronic ground states after spontaneous emission. Many of the observed lines from the spectra are consistent with transitions from the X$^1Σ^+$ ground electronic state to either the B$^1Π$ or D$^1Π$ electronic states that have been previously observed, with levels possibly as low as X$^1Σ^+$ $(v'' = 2)$ being populated. We do not observe decay to weakly bound vibrational levels of the X$^1Σ^+$ or a$^3Σ^+$ electronic states in the spectra. We also deduce a lower bound of 3900 cm$^{-1}$ for the dissociation energy of the LiRb$^+$ molecular ion.

physics.atom-ph↗

arXiv2014

Interspecies collision-induced losses in a dual species 7Li-85Rb magneto-optical trap

In this article, we report the measurement of collision-induced loss rate coefficients β_{Li,Rb} and β_{Rb,Li}, and also discuss means to significantly suppress such collision induced losses. We first describe our dual-species magneto-optical trap (MOT) that allows us to simultaneously trap > 5x10^8 7Li atoms loaded from a Zeeman slower and > 2x10^8 85Rb atoms loaded from a dispenser. We observe strong interspecies collision-induced losses in the MOTs which dramatically reduce the maximum atom number achievable in the MOTs. We measure the trap loss rate coefficients β_{Li,Rb} and β_{Rb,Li}, and, from a study of their dependence on the MOT parameters, determine the cause for the losses observed. Our results provide valuable insights into ultracold collisions between 7Li and 85Rb, guide our efforts to suppress collision induced losses, and also pave the way for the production of ultracold 7Li85Rb molecules.

physics.atom-ph↗

arXiv2014

Photoassociation of ultracold LiRb* molecules: observation of high efficiency and unitarity-limited rate saturation

We report the production of ultracold heteronuclear 7Li85Rb molecules in excited electronic states by photoassociation (PA) of ultracold 7Li and 85Rb atoms. PA is performed in a dual-species 7Li-85Rb magneto-optical trap (MOT) and the PA resonances are detected using trap loss spectroscopy. We identify several strong PA resonances below the Li (2s 2S1/2) + Rb (5p 2P3/2) asymptote and experimentally determine the long range C6 dispersion coefficients. We find a molecule formation rate (P_LiRb) of 3.5x10^7 s^-1 and a PA rate coefficient (K_PA) of 1.3x10^-10 cm^3/s, the highest among heteronuclear bi-alkali molecules. At large PA laser intensity, we observe the saturation of the PA rate coefficient (K_PA) close to the theoretical value at the unitarity limit.

physics.atom-ph↗

arXiv2014

Formation of ultracold LiRb molecules by photoassociation near the Li (2s 2S1/2) + Rb (5p 2P1/2) asymptote

We report the production of ultracold 7Li85Rb molecules by photoassociation (PA) below the Li (2s 2S1/2) + Rb (5p 2P1/2) asymptote. We perform PA spectroscopy in a dual-species 7Li-85Rb magneto-optical trap (MOT) and detect the PA resonances using trap loss spectroscopy. We observe several strong PA resonances corresponding to the last few bound states, assign the lines and derive the long range C6 dispersion coefficients for the Li (2s 2S1/2) + Rb (5p 2P1/2) asymptote. We also report an excited-state molecule formation rate (P_LiRb) of ~10^7 s^-1 and a PA rate coefficient (K_PA) of ~4x10^-11 cm^3/s, which are both among the highest observed for heteronuclear bi-alkali molecules. These suggest that PA is a promising route for the creation of ultracold ground state LiRb molecules.

physics.atom-ph↗

arXiv2013

Measurement of the radial matrix elements of the $6s \: ^2S_{1/2} \rightarrow 7p \: ^2P_{J} $ transitions in atomic cesium

We report measurements of the absorption strength of the cesium $6s \: ^2S_{1/2} \rightarrow 7p \: ^2P_{3/2} $ and the $6s \: ^2S_{1/2} \rightarrow 7p \: ^2P_{1/2} $ transitions at $λ= 456$ nm and 459 nm, respectively, in an atomic vapor cell. By simultaneously measuring the absorption strength on the Cs D$_1$ line ($6s \: ^2S_{1/2} \rightarrow 6p \: ^2P_{1/2} $), for which the electric dipole transition moment is precisely known, we are able to determine the reduced dipole matrix elements for these two lines. We report $\langle 7P_{3/2} || r || 6S_{1/2} \rangle = 0.5780 \: (7) \: a_0$ and $\langle 7P_{1/2} || r || 6S_{1/2} \rangle = 0.2789 \: (16) \: a_0$, with fractional uncertainties of 0.12% and 0.6%, respectively. Through these measurements, we can reduce the discrepancy between values of the tensor polarizability for the Cs $6s \: ^2S_{1/2} \rightarrow 7s \: ^2S_{1/2} $ transition that have been determined through two different methods.

physics.atom-ph↗

arXiv2011

Mode-hop-free tuning over 135 GHz of external cavity diode lasers without anti-reflection coating

We report an external cavity diode laser (ECDL), using a diode whose front facet is not antireflection (AR) coated, that has a mode-hop-free (MHF) tuning range greater than 135 GHz. We achieved this using a short external cavity and by simultaneously tuning the internal and external modes of the laser. We find that the precise location of the pivot point of the grating in our laser is less critical than commonly believed. The general applicability of the method, combined with the compact portable mechanical and electronic design, makes it well suited for both research and industrial applications.

physics.atom-ph↗

arXiv2011

Laser spectroscopy of the X 1Σ+ and B 1Π states of the LiRb molecule

We have studied the X 1Σ+ and B 1Π states of 7Li85Rb using Laser Induced Fluorescence (LIF) spectroscopy and Fluorescence Excitation Spectroscopy (FES). We extract molecular constants for levels v" = 0-2 of the X 1Σ+ state and levels v' = 0-20 of the B 1Π state. For the B 1Π state, we have observed rotational perturbations in the e-parity component of the v' = 2 level, and determined the dissociation energy. We discuss implications of our measurements in finding efficient photoassociation pathways for production of ultra-cold ground state LiRb molecules, and their detection via state selective ionization.

physics.atom-ph↗

arXiv2010

Analysis of two-pathway coherent control for precision measurement of weak optical transitions

We present a new technique based on two-pathway optical coherent control for the sensitive detection and precise measurement of highly-forbidden transitions in atomic systems. Specifically, we show that ($ω$, 2$ω$) coherent control can be applied to the measurement of the magnetic dipole and electroweak parity nonconserving amplitudes in atomic cesium, with the principal advantage of reduced systematic errors related to field reversals often encountered in previous measurements of these effects. We present a complete analysis in one specific geometry, and discuss prospects for improved laboratory determinations of these weak transition amplitudes.

physics.atom-ph↗