We propose to utilize the ${}^1\mathrm{\Sigma }{-}^1\mathrm{\Sigma }$ electronic transition system for direct laser cooling of heteronuclear diatomic molecules. AgH, as well as its deuterium isotopolog AgD, is used as an example to illustrate the cooling schemes. Potential-energy curves and relevant molecular parameters of both AgH and AgD, including the spin-orbit constants and the electronic transition dipole moments, are determined in internally contracted multiconfiguration-reference configuration interaction calculations. The highly diagonal Franck-Condon matrices of the $A{}^1{\mathrm{\Sigma }}^{+}-X{}^1{\mathrm{\Sigma }}^{+}$ transitions predicted by the calculations suggest the existence of quasi-closed-cycle transitions, which renders these molecules suitable for direct laser cooling. By solving rate equations numerically, we demonstrated that both AgH and AgD molecules can be cooled from 25 K to 2 mK temperature in approximately 20 ms. Our investigation elucidates and supports the hypothesis that molecules in the simplest ${}^1\mathrm{\Sigma }{-}^1\mathrm{\Sigma }$ system can serve as favorable candidates for direct laser cooling.

Tapered nanofiber is an efficient tool for enhancing light–matter interactions. Here, we experimentally demonstrate the ladder-type electromagnetically induced transparency (EIT) in one-dimensional atomic lattices near an optical nanofiber (ONF). A typical EIT signal is well fitted from experimental data according to a semiclassical model and implies a transmission nearly 35%. We investigate the dependence of EIT transmission on the coupling power and its saturation condition. In addition, we show a large fraction of the transmission spectral broadening is induced by lattice effects. Our results may pave the road towards generating correlations and entanglement through four-wave mixing with ONFs, which may facilitate the realization of efficient quantum optical networks.

We investigate the dynamical process of optically trapped X¹Σ⁺ (v′′ = 0) state ⁸⁵Rb¹³³Cs molecules distributed in J′′ = 1 and J′′ = 3 rotational states.

We report the observation of microwave coherent control of rotational states of ultracold ⁸⁵ Rb ¹³³ Cs molecules formed in their vibronic ground state by short-range photoassociation.

We present a simple, low cost and robust method to measure zero-crossing temperature (ZCT) of an ultralow expansion (ULE) cavity. Low cost fiber electro-optic modulator (EOM) and free space EOM as a frequency bridge and a frequency ruler respectively are used to precisely measure the frequency of cavity mode relative to atom transition which acts as an absolute reference frequency. Neither an expensive optical frequency comb and another ULE cavity-based stabilized laser for reference frequency, nor Pound–Drever–Hall locking system for coupling laser is required, but still allows easily using data acquisition card to record abundant data of cavity mode frequency in short term. Using our presented method, the ZCT fitting error can reach 0.01 °C and the total uncertainty can reach 0.22 °C, meaning that our presented method is accuracy and reliable.

We investigate the production of cold ⁸⁵Rb¹³³Cs molecules in the lowest vibronic level of the ground electronic state via the B¹Π₁ short-range state. The photoassociation (PA) spectra of the B¹Π₁ state, including newly observed transition to 2 vibronic levels, are obtained by high sensitivity time-of-flight mass spectrometry. Based on these PA spectra, the harmonic and anharmonic constants of vibronic states are obtained, resulting in predicted vibronic energies with an uncertainty of 1–2 cm⁻¹. The B¹Π₁ (v = 3) state is found to have the maximum production rate for ground-state molecules with a value of 3(1) × 10⁴ s⁻¹, which is 3 times larger than the value via the previously studied $2^3{\mathrm{\Pi }}_{0^{+}}$ (v = 10, J = 0) state with two-photon cascade decay. The populations of J = 0, 1, and 2 rotational levels of X¹Σ⁺ (v = 0) state molecules formed via the B¹Π₁ (v = 3, J = 1) state are measured to be around 20%, 40%, and 20%. To quantify the coupling strength between the B¹Π₁ (v = 3) state and X¹Σ⁺ (v = 0) state, the transition dipole moment between them is measured to be 7.2(2) × 10⁻³ea₀, which is also 3 times larger than the value between the $2^3{\mathrm{\Pi }}_{0^{+}}\left(v=10\right)$ state and X¹Σ⁺ (v = 0) state, meaning the B¹Π₁ (v = 3) state has a stronger coupling with the X¹Σ⁺ (v = 0) state. Our detailed measurements provide relevant parameters for investigation on direct stimulated Raman adiabatic passage transfer between the atomic scattering state and molecular bound state for ⁸⁵Rb¹³³Cs molecules.