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Data set to accompany R. C. Schofield et al., "Efficient excitation of dye molecules for single photon generation", J. Phys. Commun. 2, 115027 (2018), https://dx.doi.org/10.1088/2399-6528/aaf09a. The data from all plots is included, and a Mathematica notebook is included to extract all of the data for processing., {"references":["R. C. Schofield et al., \"Efficient excitation of dye molecules for single photon generation\", J. Phys. Commun. 2, 115027 (2018). https://dx.doi.org/10.1088/2399-6528/aaf09a"]}

A reliable photon source is required for many aspects of quantum technology. Organic molecules are attractive for this application because they can have high quantum yield and can be photostable, even at room temperature. To generate a photon with high probability, a laser must excite the molecule efficiently. We develop a simple model for that efficiency and discuss how to optimise it. We demonstrate the validity of our model through experiments on a single dibenzoterrylene (DBT) molecule in an anthracene crystal. We show that the excitation probability cannot exceed 75% at room temperature, but can increase to over 99% if the sample is cooled to liquid nitrogen temperature. The possibility of high photon generation efficiency with only modest cooling is a significant step towards a reliable photon source that is simple and practical.

We demonstrate one-dimensional sub-Doppler laser cooling of a beam of YbF molecules to 100 μK. This is a key step towards a measurement of the electron's electric dipole moment using ultracold molecules. We compare the effectiveness of magnetically-assisted and polarization-gradient sub- Doppler cooling mechanisms. We model the experiment and fi nd good agreement with our data.

We present the properties of a magneto-optical trap (MOT) of CaF molecules. We study the process of loading the MOT from a decelerated buffer-gas-cooled beam, and how best to slow this molecular beam in order to capture the most molecules. We determine how the number of molecules, the photon scattering rate, the oscillation frequency, damping constant, temperature, cloud size and lifetime depend on the key parameters of the MOT, especially the intensity and detuning of the main cooling laser. We compare our results to analytical and numerical models, to the properties of standard atomic MOTs, and to MOTs of SrF molecules. We load up to $2 \times 10^4$ molecules, and measure a maximum scattering rate of $2.5 \times 10^6$ s$^{-1}$ per molecule, a maximum oscillation frequency of 100 Hz, a maximum damping constant of 500 s$^{-1}$, and a minimum MOT rms radius of 1.5 mm. A minimum temperature of 730 $\mu$K is obtained by ramping down the laser intensity to low values. The lifetime, typically about 100 ms, is consistent with a leak out of the cooling cycle with a branching ratio of about $6 \times 10^{-6}$. The MOT has a capture velocity of about 11 m/s., Comment: 27 pages, 16 figures

We report a robust technique for laser frequency stabilisation that enables the reproducible loading of in excess of 109 Yb atoms from a Zeeman slower directly into a magneto-optical trap (MOT) operating on the 1S0 → 3P1 transition, without the need for a first stage MOT on the 1S0 → 1P1 transition. We use a simple atomic beam apparatus to generate narrow fluorescence signals on both the 399 nm 1S0 → 1P1 transition used for the Zeeman slower and the 556 nm 1S0 → 3P1 transition. We present in detail the methods for obtaining spectra with a high signalto-noise ratio and demonstrate error signals suitable for robust frequency stabilisation. Finally we demonstrate the stability and precision of our technique through sensitive measurements of the gravitational sag of the Yb MOT as a function of the intensity of the laser cooling beams, which are in good agreement with theory. These results will be important for efficient loading of the atoms into an optical dipole trap.