Absorption Imaging of Ultracold Atoms on Atom Chips

Imaging ultracold atomic gases close to surfaces is an important tool for the detailed analysis of experiments carried out using atom chips. We describe the critical factors that need be considered, especially when the imaging beam is purposely reflected from the surface. In particular we present methods to measure the atom-surface distance, which is a prerequisite for magnetic field imaging and studies of atom surface-interactions.Comment: 12 pages, 8 figures. v2 contains updated figures, modifications to tex

Surveys and investigations for sportfish management in lakes and rivers in Illinois

Sportfishing in Illinois is a major recreational activity and source of revenue and proper management of fish populations is paramount to maintaining the quality of the resource. Many different management strategies can be implemented in an attempt to improve the fishery, often without adequate evaluation. Management decisions utilize techniques that may improve the fishery in a particular system. Management techniques often are implemented without being evaluated using scientific methods and instead are based on anecdotal evidence. It is important to evaluate management practices in order to further understand if they are producing the desired fishery and if the current management action addresses the factors that may be limiting to a fishery. Therefore there is a need for more intensive scientific evaluation of management techniques in order to provide managers with evidence that these techniques can be used to produce the desired benefits.Stocking is a common tool utilized in Illinois to increase largemouth bass populations. However survival of stocked fish has been documented to be low when stocked on top of natural populations. There are a number of techniques that need to be evaluated to determine if stocking survival can be increased. We continued evaluating stocking techniques to improve survival of stocked largemouth bass. Three lakes were stocked with largemouth bass, with half the fish stocked at the boat ramp and half dispersed throughout the lake and into woody or vegetated habitat. Very few stocked fish have been recaptured from any stockings conducted thus far regardless of method. No one stocking method experienced greater growth or survival and the increased handling may contribute to the low survival. CPUE of stocked fish in this experiment has been lower than observed in stockings conducted in previous studies we have conducted and we hope to observe greater survival in future segments in order to evaluate the success of these two stocking strategies.Muskellunge are commonly stocked in Illinois as there is no documented successful reproduction. It is unclear what stock of muskellunge is best suited to maximize growth and survival in Illinois waters. We conducted final sampling during this segment and in this report present final summary of growth and survival comparisons among the three stocks from Mingo, Pierce, and Sam Dale Lakes. We compare growth and survival of muskellunge from the Upper Mississippi River drainage stock, the Ohio River drainage stock, and the Illinois North Spring Lake progeny in these three Illinois lakes. Populations were sampled by electrofishing and modified fyke net surveys during spring. Data was compiled from all years to describe long-term trends in growth and survival of muskellunge stocks in Illinois. Across years and lakes, the Ohio River drainage stock and the Illinois population generally appear to have similar growth rates through adulthood. Few Upper Mississippi River drainage stock were available for growth comparisons. Analysis of body morphology indicates that fish from the Upper Mississippi River drainage are consistently leaner than those of the other stocks. Results from lake introductions suggest that after the first summer following stocking, the Ohio River drainage stock and Illinois population typically have similar rates of survival, both of which are higher than the Upper Mississippi River drainage stock. This pattern led to consistently lower survival of Upper Mississippi River drainage stock year classes to adulthood as well. The Ohio River drainage stock and Illinois population show similar survival both to adulthood and annually through adult age classes. The specific mechanism responsible for differences in survival rate among stocks is still unknown. Information on growth and survival of muskellunge stocks at varying latitudes will aid in source selection and optimization of limited hatchery resources. Based on these results, we recommend stocking Ohio River drainage or Spring Lake progeny in Illinois lakes. Mississippi River drainage fish will have lower growth and survival in Illinois than these two populations.In addition to largemouth bass and muskellunge, crappie are commonly stocked to enhance populations. Blacknose crappie have recently been used in stocking efforts because of their distinct mark and their ability to survive handling and hatchery truck transport. Blacknose are a type of black crappie that was originally stocked because the distinct mark and the low occurrence in the wild made it easy to identify stocked fish to evaluate stocking success. There has been some suggestion that blacknose crappie have potential growth and fitness advantages over black crappie, but this has been untested in the field. In addition, little is known about the interbreeding of blacknose crappie with native black crappie or the white crappie species. In this segment, we collected black, white and blacknose crappie from source populations in Illinois and established brood ponds at the Sam Parr Biological Station. In addition blacknose crappie were obtained from Tennessee to compare to the Illinois naturalized fish. In the next segment, we will stock and evaluate the relative growth of age-0 white, black, and blacknose crappie in experimental ponds. When rearing ponds are drained in the next segment, we will estimate abundance and growth of white, black, blacknose, and black x blacknose hybrid crappie as well as the prevalence of the black stripe in the blacknose and black x blacknose hybrid ponds. In addition, we aided in blacknose crappie brood stock collection for the Jake Wolf Memorial Fish Hatchery to establish rearing ponds. Fish reared at the hatchery will be used to stock the Illinois River in the Starved Rock Pool (RM 240) near Ottawa, IL. We will also evaluate the success of this stocking in the next segment. Harvest regulations are commonly employed by fisheries managers to protect overharvest of fish populations or manage size structure. There are a large variety of regulations used in Illinois with varying management goals. In this study, we continued to assess largemouth bass populations in lakes with varying harvest regulations. The default largemouth bass regulation in Illinois is no length limit with a 6 fish bag. This was by far the most common regulation, followed by a standard 14 inch 6 fish bag. We observed some evidence that lakes with slot limits had a greater number of memorable fish, but no significant differences in abundance in any size class of largemouth bass was detected. Lakes with restrictive regulations showed similar largemouth bass size structure and abundance as lakes allowingallharvest. Low harvest ratesor poor compliance to regulations may result in no differences and will be evaluated in future segments.We also began to examine crappie regulations in Illinois lakes and how they relate to crappie populations. We determined regulations for lakes with DNR data available in the FAS database resulting in 327 lakes (46 white crappie only, 137 black crappie only, and 144 with both. Most lakes had unregulated crappie populations. The most common regulation types were bag limits and length/bag limits. Bag limits ranged from 5 -30 fish per day and length limits were either 9 or 10 inches. We found that lakes with length/bag regulations have significantly higher CPUEs than lakes with bag limits or lakes with no regulations. CPUE of crappie from lakes with bag limits was not different than unregulated lakes.Length and bag regulations may be appropriate to utilize to increase the number of crappie in a lake. We will continue to examine crappie regulations and include information on size structure in future reports.Angling tournaments are becoming increasingly popular. Although most tournaments practice live release, there can be high delayed mortality or a variety of sub-lethal impacts of competitive angling tournaments on the individual fish. Previous research has focused on measuring and reducing the stress of individual fish caught in tournaments, but little work has focused on the effect of these practices on the entire fish population. In this study, we continued to assess tournament activity and make comparisons with largemouth bass populations in a number of lakes in Illinois.We contacted lake managers and tournament directors to obtain competitive bass fishing tournament results to quantify the level of tournament activity on a lake and relate it to largemouth bass populations. Information from tournaments conducted on 12lakes was used to evaluate varying tournament pressure in addition to 4 lakes with no tournaments activity. Tournament pressure (angler hours per acre) varied from 0 to 21.8 hours/acre and the mean number of tournaments a year was 19 (range 0 –57). Larger lakes tended to have larger tournaments with a higher number of participants, but lake size was not related to total tournament pressure or the number of tournaments. The CPUE of memorable sized fish in electrofishing samples was the only fish population variable that was related to tournament pressure. Lakes with higher tournament pressure had fewer memorable sized fish in electrofishing samples. We did not detect any changes in abundance or size structure of largemouth bass vulnerable to tournament angling (> 355 mm) or production of young-of-year fish related to tournament pressure. We will continue to collect tournament and largemouth bass population data on these lakes and add additional lakes to this analysis as part of future segments to further understand the influence of tournaments on largemouth bass populations.In addition we have conducted experimental tournament angling on Ridge Lake in order to determine how tournaments can effect reproduction, abundance, and growth of largemouth bass. In this segment, we conducted spring largemouth bass tournaments while fish were on the nest and compared the changes in the fish population to previous years with tournaments and years with no tournaments. We observed no consistent changes in young-of-year production or adult abundance for largemouth bass that was related to tournament activity in the spring. We will continue to alternate tournament and no tournament years to further evaluate the potential effects of tournaments on lake wide recruitment.In addition to stocking and regulations, habitat restoration is critical to managing sportfish populations. The lack of suitable habitat for sportfish spawning, feeding and cover from predators can greatly limit a population. Understanding the importance of habitat and how to manage habitat conditions is important to managers. We have continued to conduct habitat manipulations in a number of lakes in an attempt to enhance largemouth bass populations. We continue to evaluate vegetation plantings at Lake Paradise, drawdown and rotenone efforts at Dolan and Woods Lakes, and vegetation removal through chemical treatments at Airport and Stillwater Lakes. We have observed little change in largemouth bass populations at Lake Paradise due to difficulties in establishing vegetation. Woods Lake is currently drawn down and will be rotenone treated to remove gizzard shad and carp this winter. We will begin evaluating fish populations when it is allowed to refill. Dolan Lake was drawn down to encourage vegetation establishment and rotenone treated to remove gizzard shad and carp. Despite a rebound in the gizzard shad densities, carp have not reestablished in the lake and the vegetation cover has significantly increased coinciding with an increase in largemouth bass densities in this lake. Vegetation removal treatments at Airport Lake have not been entirely successful. We have not been able to document a decrease in vegetation density and therefore no changes in largemouth bass populations were observed. Stillwater Lake was successfully treated for vegetation and the lake has remained at a lower vegetation density following initial treatment. We have also been measuring vegetation density and cover in 11 lakes and evaluate how largemouth bass populations vary among different vegetation types, cover, and fluctuations.We observed few differences in catch rates for young-of-year or adult largemouth bass associated with vegetation cover or shoreline vegetation in 2012. Vegetation has traditionally been related to prey resources (benthic invertebrates, zooplankton, prey fish) however it was not significantly related in 2012. We will continue to evaluate trends in fish populations related to vegetation density in future segments.It is important to quantify habitat in a system in order to fully understand factors that may be limiting a fishery. In mid-sized rivers there is not a standardized method for evaluating habitat in Illinois. Research is needed to create a habitat evaluation method for mid-sized rivers and relate these habitat measures to fish populations.We initiated a project in this segment to address sampling needs for non wadable river habitat and relate habitat to fish communities. We have begun to develop and implement a technique using side scan sonar to map river habitat. We will be able to use this technique to quantify habitat types along with more tradition sampling methods. We will sample fish associated with each habitat type and evaluate relationships between them initially in the Kaskaskia River and expanding to other rivers in future segments.Reproduction and the survival of fish to adulthood can be influenced by a multitude of factors. Understanding variables related to recruitment of fish populations can aid in developing management strategies or identifying limiting factors in a system. Many management practices are focused on enhancing natural recruitment by reducing mortality through practices such as fishing refuges or escapement barriers. Fishing refuges can limit disturbance of fish populations during spawning and protect juvenile and adult fish from fishing mortality and may increase natural recruitment, but have not been well evaluated. We continued to assess two fishing refuges in Otter Lake to determine the potential benefits to spawning and survival of largemouth bass. We observed no differences in CPUE or seine catch of young-of-year or adult largemouth bass in closed refuge sites and sites opento fishing. The refuge has only been in place for 3 years and it may take more time to benefit the fish population. Previous research at Clinton Lake showed increases in largemouth bass numbers in refuge locations, but the results were not evident until after a few years. We will continue to follow changes in the largemouth bass population in Otter Lake to determine how they are influenced by closed fishing refuges. Emigration or “escapement” of sportfish from reservoirs over the impounding barrier is commonly viewed as a major limitation in the successful development of high density populations. Reports and anecdotal evidence suggest that this problem is particularly ubiquitous for muskellunge in the Midwest. However, little documented information exists on the patterns and magnitude of escapement, particularly for fish that occur in low densities such as muskellunge.In this segment, we continued to monitor muskellunge escapement in Lakes Mingo and Sam Dale. Both lakes have a PIT tag array installed on the spillway that will monitor the passage of any tagged fish. Muskellunge were captured in the spring during four weeks of fyke netting. We determined population estimates using mark recapture techniques and PIT tagged all muskellunge upon release.Despite observing high levels of spillway escapement in 2011 at Sam Dale, escapement was not observed in either lake in 2012. In 2012, there was little flow over the dams due to a dry summer season and we did not observe any escapement of muskellunge. Spring rain in 2013 has provided the potential of spillway escapement. We will download data from the receivers and report our observations in the next segment.In this segment, we began to evaluate crappie recruitment in a number of lakes. We initiated spring and fall electrofishing and fyke netting to assess white, black, and blacknose crappie populations. We collected fish for dissection and otolith reading to determine age, growth, and maturity status. We also collected samples to assess prey resources and predator abundance in each study lake. We collected monthly water quality, zooplankton, larval fish and seasonal benthic invertebrate samples. Vegetation was surveyed in June and August and water level was recorded. In future segments we will use this data to determine what factors are related to crappie recruitment and make recommendations for managing crappie populations.In order to assess sportfish populations and compare populations across Illinois, it is critical to use standardized gears that are efficient in collecting the targeted fish species. Standardized practices for population assessments in Illinois have traditionally been AC shoreline electrofishing. Alternative electrofishing gears using direct current have become more popular recently due to perceived greater efficiency for certain species of fish. There is a need to evaluate how catch rates vary between the AC and DC electrofishing inorder to compare historic data if gear changes are made. We conducted AC and DC electrofishing runs on four lakes in both spring and fall. Catch rates for largemouth bass, crappie, and bluegill were similar for both small and large fish between gears. We did observe greater catch rates for gizzard shad and common carp when using DC gear. We will continue to conduct AC and DC sampling and future analyses will focus on more species and the size of fish that is captured.IDNR Division of Fisheries U.S. Fish & Wildlife Serviceunpublishednot peer reviewe

Prethermalization in one-dimensional Bose gases: Description by a stochastic Ornstein-Uhlenbeck process

We experimentally study the relaxation dynamics of a coherently split one-dimensional Bose gas using matterwave interference. Measuring the full probability distributions of interference contrast reveals the prethermalization of the system to a non-thermal steady state. To describe the evolution of noise and correlations we develop a semiclassical effective description that allows us to model the dynamics as a stochastic Ornstein-Uhlenbeck process

A Kapitza–Dirac–Talbot–Lau interferometer for highly polarizable molecules

Research on matter waves is a thriving field of quantum physics and has recently stimulated many investigations with electrons, neutrons, atoms, Bose-condensed ensembles, cold clusters and hot molecules. Coherence experiments with complex objects are of interest for exploring the transition to classical physics, for measuring molecular properties and they have even been proposed for testing new models of space-time. For matter-wave experiments with complex molecules, the strongly dispersive effect of the interaction between the diffracted molecule and the grating wall is a major challenge because it imposes enormous constraints on the velocity selection of the molecular beam. We here describe the first experimental realization of a new interferometer that solves this problem by combining the advantages of a Talbot-Lau setup with the benefits of an optical phase grating and we show quantum interference with new large molecules.Comment: 13 pages, 4 figure

Real-time single-molecule imaging of quantum interference

The observation of interference patterns in double-slit experiments with massive particles is generally regarded as the ultimate demonstration of the quantum nature of these objects. Such matter–wave interference has been observed for electrons, neutrons, atoms and molecules and, in contrast to classical physics, quantum interference can be observed when single particles arrive at the detector one by one. The build-up of such patterns in experiments with electrons has been described as the “most beautiful experiment in physics”. Here, we show how a combination of nanofabrication and nano-imaging allows us to record the full two-dimensional build-up of quantum interference patterns in real time for phthalocyanine molecules and for derivatives of phthalocyanine molecules, which have masses of 514 AMU and 1,298 AMU respectively. A laser-controlled micro-evaporation source was used to produce a beam of molecules with the required intensity and coherence, and the gratings were machined in 10-nm-thick silicon nitride membranes to reduce the effect of van der Waals forces. Wide-field fluorescence microscopy detected the position of each molecule with an accuracy of 10 nm and revealed the build-up of a deterministic ensemble interference pattern from single molecules that arrived stochastically at the detector. In addition to providing this particularly clear demonstration of wave–particle duality, our approach could also be used to study larger molecules and explore the boundary between quantum and classical physics