Fast, precise, and widely tunable frequency control of an optical parametric oscillator referenced to a frequency comb

Optical frequency combs (OFC) provide a convenient reference for the frequency stabilization of continuous-wave lasers. We demonstrate a frequency control method relying on tracking over a wide range and stabilizing the beat note between the laser and the OFC. The approach combines fast frequency ramps on a millisecond timescale in the entire mode-hop free tuning range of the laser and precise stabilization to single frequencies. We apply it to a commercially available optical parametric oscillator (OPO) and demonstrate tuning over more than 60 GHz with a ramping speed up to 3 GHz/ms. Frequency ramps spanning 15 GHz are performed in less than 10 ms, with the OPO instantly relocked to the OFC after the ramp at any desired frequency. The developed control hardware and software is able to stabilize the OPO to sub-MHz precision and to perform sequences of fast frequency ramps automatically.Comment: 8 pages, 7 figures, accepted for publication in Review of Scientific Instrument

Optoelectrical cooling of polar molecules to sub-millikelvin temperatures

We demonstrate direct cooling of gaseous formaldehyde (H2CO) to the microkelvin regime. Our approach, optoelectrical Sisyphus cooling, provides a simple dissipative cooling method applicable to electrically trapped dipolar molecules. By reducing the temperature by three orders of magnitude and increasing the phase-space density by a factor of ~$10^4$ we generate an ensemble of $3\cdot10^5$ molecules with a temperature of about 420\mu K, populating a single rotational state with more than 80% purity

Rotational cooling of trapped polyatomic molecules

Controlling the internal degrees of freedom is a key challenge for applications of cold and ultracold molecules. Here, we demonstrate rotational-state cooling of trapped methyl fluoride molecules (CH3F) by optically pumping the population of 16 M-sublevels in the rotational states J=3,4,5, and 6 into a single level. By combining rotational-state cooling with motional cooling, we increase the relative number of molecules in the state J=4, K=3, M=4 from a few percent to over 70%, thereby generating a translationally cold (~30mK) and nearly pure state ensemble of about 10^6 molecules. Our scheme is extendable to larger sets of initial states, other final states and a variety of molecule species, thus paving the way for internal-state control of ever larger molecules

Novel Separation Methods using Electrodialysis/Electrodeionization for Product Recovery and Power Generation

The use of electrodialytic separations for the purification of products has been a vital technique for the past 50 years in the chemical industry. Originally used for demineralization and desalination, electrodialysis and its counterparts have expanded to assist in product purification, waste and hazard removal, and power generation. This research focused on the development of high purity organic acids purification with low power requirements. Work resulted in the development of a new type of electrodialysis process, specifically the use of ionic liquids as a secondary solvent for the development of dual solvent electrodialysis. Through dual solvent electrodialysis, ions were recovered and concentrated from products streams while enacting a solvent change. This allowed the requirements and scope of secondary purification steps to be greatly reduced and, in some cases, no longer necessary. Application of ion exchange wafers further improved separation performance of dual solvent electrodialysis. This electrodeionization technique resulted in separation efficiencies and power consumption levels similar to those of commercially implemented organic acid recovery methods with reduced complexity. Additional efforts in power generation through a technique known as reverse electrodialysis were also pursued and a discussion on the implication technology on meeting future energy demands will presented. Through this research, new avenues and applications for electrodialytic separation are now possible

Stabilization of the perovskite phase in the Y-Bi-O system by using a BaBiO3_{3} buffer layer

A topological insulating phase has theoretically been predicted for the thermodynamically unstable perovskite phase of YBiO$_{3}$. Here, it is shown that the crystal structure of the Y-Bi-O system can be controlled by using a BaBiO$_{3}$ buffer layer. The BaBiO$_{3}$ film overcomes the large lattice mismatch of 12% with the SrTiO$_{3}$ substrate by forming a rocksalt structure in between the two perovskite structures. Depositing an YBiO$_{3}$ film directly on a SrTiO$_{3}$ substrate gives a fluorite structure. However, when the Y-Bi-O system is deposited on top of the buffer layer with the correct crystal phase and comparable lattice constant, a single oriented perovskite structure with the expected lattice constants is observed.Comment: 8 pages, 7 figures + 4 pages supporting informatio

Kite systems of order 8;Embedding of kite systems into bowtie systems

This article consist of two parts. In the first part, we enumerate the kite systems of order 8; in the second part, we consider embedding kite systems into bowtie systems