The properties of bosonic Ytterbium photoassociation spectra near the intercombination transition $^{1}S_{0}$--$^{3}P_{1}$ are studied theoretically at ultra low temperatures. We demonstrate how the shapes and intensities of rotational components of optical Feshbach resonances are affected by mass tuning of the scattering properties of the two colliding ground state atoms. Particular attention is given to the relationship between the magnitude of the scattering length and the occurrence of shape resonances in higher partial waves of the van der Waals system. We develop a mass scaled model of the excited state potential that represents the experimental data for different isotopes. The shape of the rotational photoassociation spectrum for various bosonic Yb isotopes can be qualitatively different.
Optical frequency measurements of the intercombination line $(6s^{2})\,^{1}S_{0} -(6s6p)\,^{3}P_{1}$ in the isotopes of ytterbium are carried out with the use of sub-Doppler fluorescence spectroscopy on an atomic beam. A dispersive signal is generated to which a master laser is locked, while frequency counting of an auxiliary beat signal is performed via a frequency comb referenced to a hydrogen maser. The relative separations between the lines are used to evaluate the $^{3}P_{1}$-level magnetic dipole and electric quadrupole constants for the fermionic isotopes. The center of gravity for the …
We demonstrate a high-flux and low transverse temperature atomic beam of ytterbium by applying two-dimensional cooling using the ${}^1\mathrm{S}_0\text{-}{}^3\mathrm{P}_1$ intercombination transition to the cold atomic beam produced by the dipolar-allowed ${}^1\mathrm{S}_0\text{-}{}^1\mathrm{P}_1$ transition. The optimized transverse temperature of $11 \pm 9\,\mathrm{μK}$ and an atomic flux of $(7.5 \pm 1.0) \times 10^8\,\mathrm{atoms/s}$ are obtained for the atomic beam whose longitudinal velocity is $30\,\mathrm{m/s}$. The transverse temperature is maintained below $23\,\mathrm{μK}$, while t…
We calculate and measure the magic wavelengths for the $6s^2{}\,^1S_0-6s6p\,{}^3P_1$ intercombination transition of the neutral ytterbium atom. The calculation is performed with the \textit{ab initio} configuration interaction (CI) + all-order method. The measurement is done with laser spectroscopy on cold atoms in an optical dipole trap. The magic wavelengths are determined to be 1035.68(4) nm for the $π$ transition ($Δm = 0$) and 1036.12(3) nm for the $σ$ transitions ($|Δm| = 1$) in agreement with the calculated values. Laser cooling on the narrow intercombination transition could achieve be…
We present precise measurements of the optical Feshbach resonances (OFRs) of $^{174}$Yb atoms for the intercombination transition. We measure the photoassociation (PA) spectra of a pure $^{174}$Yb Bose-Einstein condensate, and determine the dependence of OFRs to PA laser intensities and frequencies for four least bound vibrational levels near the intercombination transition. We confirm that our measurements are consistent with the temporal decay of a BEC subjected to a PA beam in the vicinity of the fourth vibrational level from the dissociation limit.
We demonstrate a method to enhance the atom loading rate of a ytterbium (Yb) magneto-optic trap (MOT) operating on the 556 nm ${^1S}_0 \rightarrow {^3P}_1$ intercombination transition (narrow linewidth $Γ_g = 2π\times 182$ kHz). Following traditional Zeeman slowing of an atomic beam near the 399 nm ${^1S}_0 \rightarrow {^1P}_1$ transition (broad linewidth $Γ_p = 2π\times 29 $ MHz), two laser beams in a crossed-beam geometry, frequency tuned near the same transition, provide additional slowing immediately prior to the MOT. Using this technique, we observe an improvement by a factor of 6 in the …
We describe the design, construction and operation of a versatile dual-species Zeeman slower for both Cs and Yb, which is easily adaptable for use with other alkali metals and alkaline earths. With the aid of analytic models and numerical simulation of decelerator action, we highlight several real-world problems affecting the performance of a slower and discuss effective solutions. To capture Yb into a magneto-optical trap (MOT), we use the broad $^1S_0$ to $^1P_1$ transition at 399 nm for the slower and the narrow $^1S_0$ to $^3P_1$ intercombination line at 556 nm for the MOT. The Cs MOT and …
We investigate the possibility of forming Li+Yb ultracold molecules by magnetoassociation in mixtures of ultracold atoms. We find that magnetically tunable Feshbach resonances exist, but are extremely narrow for even-mass ytterbium isotopes, which all have zero spin. For odd-mass Yb isotopes, however, there is a new mechanism due to hyperfine coupling between the electron spin and the Yb nuclear magnetic moment. This mechanism produces Feshbach resonances for fermionic Yb isotopes that can be more than 2 orders of magnitude larger than for the bosonic counterparts.
Motivated by a recent experiment by Zelevinsky et al. [Phys. Rev. Lett. 96, 203201], we present the theory for photoassociation and optical Feshbach resonances of atoms confined in a tight one-dimensional (1D) or two-dimensional (2D) optical lattice. In the case of an alkaline-earth intercombination resonance, the narrow natural width of the line makes it possible to observe clear manifestations of the dimensionality, as well as some sensitivity to the scattering length of the atoms. Among possible applications, a 2D lattice may be used to increase the spectroscopic resolution by about one ord…
We demonstrate control of the collapse and expansion of an 88Sr Bose-Einstein condensate using an optical Feshbach resonance (OFR) near the 1S0-3P1 intercombination transition at 689 nm. Significant changes in dynamics are caused by modifications of scattering length by up to +- ?10a_bg, where the background scattering length of 88Sr is a_bg = -2a0 (1a0 = 0.053 nm). Changes in scattering length are monitored through changes in the size of the condensate after a time-of-flight measurement. Because the background scattering length is close to zero, blue detuning of the OFR laser with respect to …
A frequency-stabilized light source emitting at 556 nm is realized by frequency-doubling a 1112-nm laser, which is phase-locked to a fiber-based optical frequency comb. The 1112-nm laser is either an ytterbium (Yb)-doped distributed feedback fiber laser or a master-slave laser system that uses an external cavity diode laser as a master laser. We have achieved the continuous frequency stabilization of the light source over a five-day period. With the light source, we have completed the second-stage magneto-optical trapping (MOT) of Yb atoms using the 1S0 - 3P1 intercombination transition. The t…
It is possible to tune the scattering length for the collision of ultra-cold 1S0 ground state alkaline-earth atoms using an optical Feshbach resonance. This is achieved with a laser far detuned from an excited molecular level near the frequency of the atomic intercombination 1S0--3P1 transition. Simple resonant scattering theory, illustrated by the example of 40Ca, allows an estimate of the magnitude of the effect. Unlike alkali metal species, large changes of the scattering length are possible while atom loss remains small, because of the very narrow line width of the molecular photoassociati…
We demonstrate a p$-wave optical Feshbach resonance (OFR) using purely long-range molecular states of a fermionic isotope of ytterbium ^{171}Yb, following the proposition made by K. Goyal et al. [Phys. Rev. A 82, 062704 (2010)]. The p-wave OFR is clearly observed as a modification of a photoassociation rate for atomic ensembles at about 5 micro-Kelvins. A scattering phase shift variation of δη=0.022 rad is observed with an atom loss rate coefficient K=28.0*10^{-12} cm^3/s.
We report on the experimental observation of Feshbach resonances in large mass-imbalance mixtures of Erbium (Er) and Lithium (Li). All combinations between ${}^{168}$Er, ${}^{166}$Er and ${}^7$Li, ${}^6$Li are cooled to temperatures of a few microkelvin, partially by means of sympathetic cooling together with Ytterbium (Yb) as a third mixture component. The Er-Li inelastic interspecies collisional properties are studied for magnetic fields up to 680 G. In all cases resonant interspecies loss features, indicative of Feshbach resonances, have been observed. While most resonances have sub-Gauss w…
Engineering controllable, strongly interacting many-body quantum systems is at the frontier of quantum simulation and quantum information processing. Arrays of laser-cooled neutral atoms in optical tweezers have emerged as a promising platform, because of their flexibility and the potential for strong interactions via Rydberg states. Existing neutral atom array experiments utilize alkali atoms, but alkaline-earth atoms offer many advantages in terms of coherence and control, and also open the door to new applications in precision measurement and timekeeping. In this work, we present a techniqu…
Using a narrow intercombination line in alkaline earth atoms to mitigate large inelastic losses, we explore the Optical Feshbach Resonance (OFR) effect in an ultracold gas of bosonic $^{88}$Sr. A systematic measurement of three resonances allows precise determinations of the OFR strength and scaling law, in agreement with coupled-channels theory. Resonant enhancement of the complex scattering length leads to thermalization mediated by elastic and inelastic collisions in an otherwise ideal gas. OFR could be used to control atomic interactions with high spatial and temporal resolution.
Magnetically tunable scattering resonances have been used with great success for precise control of s-wave scattering lengths in ultracold atomic collisions. We describe relatively simple yet quite powerful analytic treatments of such resonances based on the analytic properties of the van der Waals long range potential. This theory can be used to characterize a number of properties of specific resonances that have been used successfully in various experiments with $^{87}$Rb, $^{85}$Rb, $^{40}$K, and $^{6}$Li. Optical Feshbach resonances are also possible and may be practical with narrow interc…
Optical Feshbach resonances [Phys. Rev. Lett. 94, 193001 (2005)] and pump-dump photoassociation with short laser pulses [Phys. Rev. A 73, 033408 (2006)] have been proposed as means to coherently form stable ultracold alkali dimer molecules. In an optical Feshbach resonance, the intensity and possibly frequency of a cw laser are ramped up linearly followed by a sudden switch-off of the laser. This is applicable to tightly trapped atom pairs. In short-pulse photoassociation, the pump pulse forms a wave-packet in an electronically excited state. The ensuing dynamics carry the wave-packet to short…
We observe a magnetic Feshbach resonance in a collision between the ground and metastable states of two-electron atoms of ytterbium (Yb). We measure the on-site interaction of doubly-occupied sites of an atomic Mott insulator state in a three-dimensional optical lattice as a collisional frequency shift in a high-resolution laser spectroscopy. The observed spectra are well fitted by a simple theoretical formula, in which two particles with an s-wave contact interaction are confined in a harmonic trap. This analysis reveals a wide variation of the interaction with a resonance behavior around a m…
We demonstrate nanometer-scale spatial control of inter-atomic interactions in a Bose-Einstein condensate of ytterbium(Yb). A pulsed optical standing wave, tuned near an optical Feshbach resonance varies the s-wave scattering length continuously across the standing wave pattern. The modulated mean-field energy with a spatial period of every 278 nm is monitored by a diffraction pattern in a time-of-flight image. We observe a wide scattering length control of up to 160 nm. The demonstrated spatial modulation of the scattering length proves that the high resolution control of atomic interactions …
Using new experimental measurements of photoassociation resonances near the $^1\mathrm{S}_0 \rightarrow \phantom{ }^3\mathrm{P}_1$ intercombination transition in $^{84}$Sr and $^{86}$Sr, we present an updated study into the mass-scaling behavior of bosonic strontium dimers. A previous mass-scaling model [Borkowski et al., Phys. Rev. A 90, 032713 (2014)] was able to incorporate a large number of photoassociation resonances for $^{88}$Sr, but at the time only a handful of resonances close to the dissociation limit were known for $^{84}$Sr and $^{86}$Sr. In this work, we perform a more thorough m…
