The narrow transition from the lowest rovibrational level of the X1Σ+ electronic ground state to the lowest vibrational level of the b3Π0 potential provides opportunities for achieving magic-wavelength trapping of ultracold bialkali molecules for enhancing their rotational coherence times. Guided by existing spectroscopic data of several perturbed and deeply-bound rovibrational states of the A1Σ+ potential [Grochola et al., Chem. Phys. Lett., 2012, 535, 17-20], we conducted a targeted spectroscopic search and report the first observation of the lowest vibrational level of the b3Π0 state in 6Li40K. The transition frequency from |X1Σ+, v = 0, J = 0〉 to |b3Π0, v' = 0, J' = 1〉 is determined to be 314 230.5(5) GHz. Assisted by microwave spectroscopy, we resolved the rotational structure of |b3Π0, v' = 0〉 and extracted a rotational constant of h × 8.576(44) GHz for the b3Π0 state. From this, we deduced an energy separation between |b3Π0, v' = 0, J' = 0〉 and |X1Σ+, v = 0, J = 0〉 of hc × 10 481.03(2) cm-1. Our work provides timely and precise information on the deeply-bound region of the b3Π0 triplet excited potential of LiK, and benefits future applications of ultracold LiK isotopologues in quantum simulation and quantum computation that demand long coherence times.

Observation of the b 3 Π, v = 0 ground state of ultracold LiK polar molecules enabling long coherence times for quantum applications.

Ultracold polar molecules represent a rapidly advancing platform at the forefront of quantum simulation, quantum computation, quantum chemistry, and precision measurement. We report an experimental investigation for improving the creation efficiency of ultracold 6Li40K ground state molecules using stimulated Raman adiabatic passage (STIRAP). We address laser amplitude/phase noise and polarization impurity to improve STIRAP efficiency. The phase noise of our two Raman lasers is suppressed effectively by extending the cavity length for the external-cavity diode lasers (ECDLs). Further, we find that even a weak polarization impurity significantly reduces the STIRAP efficiency on the single-photon resonance (Δ = 0) for 6Li40K, due to coupling to undesired molecular levels. However, STIRAP efficiencies over 90

We report the creation of ultracold ground state ^{6}Li^{40}K polar molecules with high efficiency. Starting from weakly bound molecules, stimulated Raman adiabatic passage is adopted to coherently transfer the molecules to their singlet rovibrational ground state |X^{1}Σ^{+},v=0,J=0⟩. By employing a singlet stimulated Raman adiabatic passage pathway and low-phase-noise narrow-linewidth lasers, we observed a one-way transfer efficiency of 96(4)%. Held in an optical dipole trap, the lifetime of the ground state molecules is measured to be 5.0(3) ms. The large permanent dipole moment of LiK is confirmed by applying a dc electric field on the molecules and performing Stark shift spectroscopy of the ground state. With recent advances in the quantum control of collisions, our work paves the way for exploring quantum many-body physics with strongly interacting ^{6}Li^{40}K molecules.

We present the comparison of a field-programmable-gate-array (FPGA) based digital servo module with an analog counterpart for the purpose of laser frequency stabilization to a high-finesse optical cavity. The transfer functions of both the digital and analog modules for proportional-integral-derivative control are measured. For the lasers stabilized to the cavity, we measure the singe-sideband power spectral density of fast phase noise by means of an optical beat with filtered light transmitted through the cavity. The comparison between the digital and analog modules is performed for two low-phase-noise diode lasers at 1120 and 665 nm wavelengths. The performance of the digital servo module compares well to the analog one for the lowest attained levels of 30 mrad for the integrated phase noise and 10(-3) for the relative noise power. The laser linewidth is determined to be in the sub-kHz regime, only limited by the high-finesse cavity. Our work exploits the versatility of the FPGA-based servo module (STEMlab) when used with open-source software and hardware modifications. We demonstrated that such modules are suitable candidates for remote-controlled low-phase-noise applications in the fields of laser spectroscopy and atomic, molecular, and optical physics.

We report the creation of ultracold ground state $^{6}\textrm{Li}^{40}\textrm{K}$ polar molecules with high efficiency. Starting from weakly-bound molecules state, stimulated Raman adiabatic passage (STIRAP) is adopted to coherently transfer the molecules to their singlet ro-vibrational ground state $|\textrm{X}^{1}\Sigma^{+},v=0,J=0>$. By employing a singlet STIRAP pathway and low-phase-noise narrow-linewidth lasers, we observed a one-way transfer efficiency of 96(4)\,\%. Held in an optical dipole trap, the lifetime of the ground-state molecules is measured to be 5.0(3)\,ms. The large permanent dipole moment of LiK is confirmed by applying a DC electric field on the molecules and performing Stark shift spectroscopy of the ground state. With recent advances in the quantum control of collisions, our work paves the way for exploring quantum many-body physics with strongly-interacting $^{6}\textrm{Li}^{40}\textrm{K}$ molecules.

We report on a high-resolution spectroscopic survey of 6Li40K molecules near the 2S + 4P dissociation threshold and produce a fully empirical representation for the B1Π potential by connecting available short- and long-range data. The purpose is to identify a suitable intermediate state for a coherent Raman transfer to the absolute ground state, and the creation of a molecular gas with dipolar interactions. Starting from weakly bound ultracold Feshbach molecules, the transition frequencies to twenty-six vibrational states are determined. Our data are combined with long-range measurements [Ridinger et al., EPL, 2011, 96, 33001], and near-dissociation expansions for the spin-orbit coupled potentials are fitted to extract the van der Waals C6 dispersion coefficients. A suitable vibrational level is identified by resolving its Zeeman structure and by comparing the experimentally attained g-factor to our theoretical prediction. Using mass-scaling of the short-range data for the B1Π [Pashov et al., Chem. Phys. Lett., 1998, 292, 615620] and an updated value for its depth, we model the short- and the long-range data simultaneously and produce a Rydberg-Klein-Rees curve covering the entire range.

We investigate the phase noise properties of our Raman laser system for its application in the coherent ground state transfer of LiK polar molecules and discuss recent improvements.

The 53rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics will take place from May 30 – June 3, 2022 in Orlando, Fl, USA. Virtual Presenter Help Desk

Starting from weakly bound Feshbach molecules, we demonstrate a two-photon pathway to the dipolar ground state of bi-alkali molecules that involves only singlet-to-singlet optical transitions. This pathway eliminates the search for a suitable intermediate state with sufficient singlet-triplet mixing and the exploration of its hyperfine structure, as is typical for pathways starting from triplet dominated Feshbach molecules. By selecting a Feshbach state with a stretched singlet hyperfine component and controlling the polarization of the excitation laser, we assure coupling to only a single hyperfine component of the $\textrm{A}^{1}\Sigma^{+}$ excited potential, even if the hyperfine structure is not resolved. Similarly, we address a stretched hyperfine component of the $\textrm{X}^{1}\Sigma^{+}$ rovibrational ground state, and therefore an ideal three level system is established. We demonstrate this pathway with ${}^{6}\textrm{Li}{}^{40}\textrm{K}$ molecules. By exploring deeply bound states of the $\textrm{A}^{1}\Sigma^{+}$ potential, we are able to obtain large and balanced Rabi frequencies for both transitions. This method can be applied to other molecular species.

We present spectroscopic measurements of the long range states of the 6 Li 40 K molecule near its Li(4 2 S1/2) + K(4 2 P3/2) asymptote which in combination with existing data in the short range lead to the full characterization of the B 1 Π potential with high spectroscopic resolution.This survey was conducted in the context of identifying a suitable pathway for the efficient two-photon transfer to the absolute ro-vibronic ground state of 6 Li 40 K heteronuclear dimers.

We present an efficient scheme to implement a gray optical molasses for sub-Doppler cooling of Li-6 atoms with minimum experimental overhead. To integrate the D-1 light for the gray molasses cooling into the same optical setup that is used for the D-2 light for a standard magneto-optical trap (MOT), we rapidly switch the injection seeding of a slave laser between the D-2 and the D-1 light sources. Switching times as short as 30 mu s can be achieved, inferred from monitor optical beat signals. The resulting low-intensity molasses cools a sample of N = 9 x 10(8) atoms to about 60 mu K. A maximum phase-space density of rho = 1.2 x 10(-5) is observed. On the same setup, the performance of the GM is compared to that of narrow-line cooling in an ultraviolet (UV) MOT, following the procedure in Sebastian et al. [J. Sebastian, Ch. Gross, K. Li, H. C. J. Gan, W. Li, and K. Dieckmann, Phys. Rev. A 90, 033417 (2014)]. Further, we compare the production of a degenerate Fermi gas using both methods. Loading an optical dipole trap from the gray molasses yields a quantum degenerate sample with 3.3 x 10 5 atoms, while loading from the denser UV MOT yields 2.4 x 10(6) atoms. Where the highest atom numbers are not a priority this implementation of the gray molasses technique yields sufficiently large samples for a comparatively low technical effort.

We report on an efficient production scheme for a large quantum degenerate sample of fermionic lithium. The approach is based on our previous work on narrow-line 2S(1/2) -> 3P(3/2) laser cooling resulting in a high phase-space density of up to 3 x 10(-4). This allows utilizing a large-volume crossed optical dipole trap with a total power of 45 W, leading to high loading efficiency and 8 x 10(6) trapped atoms. The same optical trapping configuration is used for rapid adiabatic transport over a distance of 25 cm in 0.9 s, and subsequent evaporative cooling. With optimized evaporation we achieve a degenerate Fermi gas with 1.7 x 10(6) atoms at a temperature of 60 nK, corresponding to T/T-F = 0.16(2). Furthermore, the performance is demonstrated by evaporation near a broad Feshbach resonance creating a molecular Bose-Einstein condensate of 3 x 10(5) lithium dimers.

This roadmap bundles fast developing topics in experimental optical quantum sciences, addressing current challenges as well as potential advances in future research. We have focused on three main areas: quantum assisted high precision measurements, quantum information/simulation, and quantum gases. Quantum assisted high precision measurements are discussed in the first three sections, which review optical clocks, atom interferometry, and optical magnetometry. These fields are already successfully utilized in various applied areas. We will discuss approaches to extend this impact even further. In the quantum information/simulation section, we start with the traditionally successful employed systems based on neutral atoms and ions. In addition the marvelous demonstrations of systems suitable for quantum information is not progressing, unsolved challenges remain and will be discussed. We will also review, as an alternative approach, the utilization of hybrid quantum systems based on superconducting quantum devices and ultracold atoms. Novel developments in atomtronics promise unique access in exploring solid-state systems with ultracold gases and are investigated in depth. The sections discussing the continuously fast-developing quantum gases include a review on dipolar heteronuclear diatomic gases, Rydberg gases, and ultracold plasma. Overall, we have accomplished a roadmap of selected areas undergoing rapid progress in quantum optics, highlighting current advances and future challenges. These exciting developments and vast advances will shape the field of quantum optics in the future.

We report on a transfer-lock laser frequency stabilization that utilizes a frequency comb (FC) and a radio frequency counter referenced to a GPS frequency standard to compensate for the frequency drifts of two lasers, which are locked to a single passive Fabry-Perot resonator (FPR). The method requires only one optical phase lock with the FC and allows transfer locking of lasers at wavelengths beyond the usable range of the FC. To attain a large frequency tuning range for the lasers, we implement optical serrodyning. We further demonstrate an efficient scheme to suppress residual amplitude modulation, thereby improving the stability of the Pound-Drever-Hall lock used in this case. The absolute frequency stability was found to be better than 2 x 10(-13) on timescales up to 300 s. Hence, together with the frequency stability on short timescales provided by the FPR, this scheme facilitates coherent Raman spectroscopy as needed for an example for the production of ultracold dipolar heteronuclear molecules. (C) 2016 Optical Society of America