Micro- and increasingly, nano-fabrication have enabled the miniaturization of atomic devices, from vapor cells to atom chips for Bose-Einstein condensation. Here we present microfabricated planar devices for thermal atomic beams. Etched microchannels were used to create highly collimated, continuous rubidium atom beams traveling parallel to a silicon wafer surface. Precise, lithographic definition of the guiding channels allowed for shaping and tailoring the velocity distributions in ways not possible using conventional machining. Multiple miniature beams with individually prescribed geometries were created, including collimated, focusing and diverging outputs. A “cascaded” collimator was realized with 40 times greater purity than conventional collimators. These localized, miniature atom beam sources can be a valuable resource for a number of quantum technologies, including atom interferometers, clocks, Rydberg atoms, and hybrid atom-nanophotonic systems, as well as enabling controlled studies of atom-surface interactions at the nanometer scale.

Regulation of electronic structure and mobility cut-on rate in two-dimensional transition metal dichalcogenides (TMDs) has attracted much attention because of its potential in electronic device design. The anisotropic Raman scattering and mobility cut-on rate of monolayer unique distorted-1T(1Td) ReS2 with external strain are determined theoretically based on the density function theory. The angle-dependent Raman spectrum of Ag-like, Eg-like and Cp models are used to discriminate and analysis structural anisotropy; the strain is exploited to adjust the structural symmetry and electronic structure of ReS2 so as to enhance mobility cut-on rate to almost 6 times of the original value. Our results suggest the use of the strain engineering in high-quality semiconductor switch device.

Crude glycerol is a primary by-product in the biodiesel production process and its large surplus blocks the development of the biodiesel industry. In this study, crude glycerol was used as a substrate to co-produce 1,3-propanediol (1,3-PD) and lactic acid through fermentation of Klebsiella pneumoniae. The final concentrations of 1,3-PD and lactic acid were 62.6 and 33.4 g/L, respectively, and the total mass conversion yield was 55.7%. The two-step salting-out extraction method was adopted for the separation of 1,3-PD and lactic acid from the fermentation broth. In the first step of extraction, the maximal partition coefficient and recovery of 1,3-PD reached 9.81 and 92.4% under the optimal conditions of 30% isopropanol and 30% potassium carbonate. Subsequently, 28% ethanol was added into the salt phase to perform the second salting-out extraction at pH 6.5. The partition coefficient and recovery of lactic acid reached 1.27 and 73.8%, respectively. All cells and most of the proteins (98.5%) were finally removed. The results suggest that crude glycerol can be used as a promising feedstock to co-produce 1,3-PD and lactic acid from fermentation broths, and this could not only reduce the production cost but also promote the further development of the biodiesel industry.

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An integrated photonic platform is proposed for strong interactions between atomic beams and annealing-free high-quality-factor ( Q ) microresonators. We fabricated a thin-film, air-clad SiN microresonator with a loaded Q of 1.55 × 10 6 around the optical transition of  87 R b at 780 nm. This Q is achieved without annealing the devices at high temperatures, enabling future fully integrated platforms containing optoelectronic circuitry. The estimated single-photon Rabi frequency (2g) is 2 π × 64 M H z 100 nm above the resonator. Our simulation result indicates that miniature atomic beams with a longitudinal speed of 0.2 m/s to 30 m/s will interact strongly with our resonator, allowing for the detection of single-atom transits and realization of scalable single-atom photonic devices. Interactions between racetrack resonators and thermal atomic beams are also simulated.

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Alkali metal dispensers have become an indispensable tool in the production of atomic vapors for magnetometry, alkali vapor cell clocks, and laser cooling experiments. A primary advantage of these dispensers is that they contain alkali metal in an inert form that can be exposed to air without hazard. However, their high temperature of operation (>600 °C) is undesirable for many applications, as it shifts the atomic speed distribution to higher values and presents a radiative heat source that can raise the temperature of its surroundings. For this reason, dispensers are typically not used in line-of-sight applications, such as atomic beam generation. In this work, we present an integrated rubidium dispenser collimating device with a thickness of only 2 mm that produces a beam of atoms traveling primarily in the forward direction. We find that the collimator plate serves to both shield the dispenser's radiation and moderate the velocity of the atomic beam so that the measured longitudinal speed distribution is comparable to that of an ordinary alkali oven at only a slightly elevated temperature of 200 °C. To confirm our theory, we also constructed another compact apparatus consisting of a dispenser and a silicon collimator and the measurements support our conclusion. Our integrated dispenser collimator will particularly be useful in integrated photonics and cavity QED on-chip, where a localized, directed source of Rb vapor in small quantities is needed.