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We observe bimodal fluorescence patterns from atoms in a fast atomic beam when the laser excitation occurs in the presence of a magnetic field and the atoms sample only a portion of the laser profile. The behavior is well explained by competition between the local intensity of the laser, which tends to generate a coherent-population-trapping (CPT) dark state in the $J=1$ to ${J}^{\ensuremath{'}}=0$ system, and the strength of an applied magnetic field that can frustrate the CPT process. This work is relevant for understanding and optimizing the detection process for clocks or other coherent systems utilizing these transitions and could be applicable to in situ calibration of the laser-atom interaction, such as the strength of the magnetic field or laser intensity at a specific location.

Long-range Rydberg interactions, in combination with electromagnetically induced transparency (EIT), give rise to strongly interacting photons where the strength, sign, and form of the interactions are widely tunable and controllable. Such control can be applied to both coherent and dissipative interactions, which provides the potential to generate novel few-photon states. Recently it has been shown that Rydberg-EIT is a rare system in which three-body interactions can be as strong or stronger than two-body interactions. In this work, we study a three-body scattering loss for Rydberg-EIT in a wide regime of single and two-photon detunings. Our numerical simulations of the full three-body wavefunction and analytical estimates based on Fermi's Golden Rule strongly suggest that the observed features in the outgoing photonic correlations are caused by the resonant enhancement of the three-body losses., 6 pages, 4 figures

There has been a recent surge of interest and progress in creating subwavelength free-space optical potentials for ultra-cold atoms. A key open question is whether geometric potentials, which are repulsive and ubiquitous in the creation of subwavelength free-space potentials, forbid the creation of narrow traps with long lifetimes. Here, we show that it is possible to create such traps. We propose two schemes for realizing subwavelength traps and demonstrate their superiority over existing proposals. We analyze the lifetime of atoms in such traps and show that long-lived bound states are possible. This work opens a new frontier for the subwavelength control and manipulation of ultracold matter, with applications in quantum chemistry and quantum simulation.

Ultracold systems offer an unprecedented level of control of interactions between atoms. An important challenge is to achieve a similar level of control of the interactions between photons. Towards this goal, we propose a realization of a novel Lennard-Jones-like potential between photons coupled to the Rydberg states via electromagnetically induced transparency (EIT). This potential is achieved by tuning Rydberg states to a F\"orster resonance with other Rydberg states. We consider few-body problems in 1D and 2D geometries and show the existence of self-bound clusters (``molecules'') of photons. We demonstrate that for a few-body problem, the multibody interactions have a significant impact on the geometry of the molecular ground state. This leads to phenomena without counterparts in conventional systems: For example, three photons in two dimensions preferentially arrange themselves in a line configuration rather than in an equilateral-triangle configuration. Our result opens a new avenue for studies of many-body phenomena with strongly interacting photons.

Single photons coupled to atomic systems have shown to be a promising platform for developing quantum technologies. Yet a bright on-demand, highly pure, and highly indistinguishable single-photon source compatible with atomic platforms is lacking. In this work, we demonstrate such a source based on a strongly interacting Rydberg system. The large optical nonlinearities in a blockaded Rydberg ensemble convert coherent light into a single collective excitation that can be coherently retrieved as a quantum field. We simultaneously observe a fully single-mode (spectral, temporal, spatial, and polarization) efficiency up to 0.098(2), a detector-background-subtracted g ( 2 ) = 5.0 ( 1.6 ) × 10 − 4 , and indistinguishability of 0.980(7), at an average photon production rate of 1.18 ( 2 ) × 10 4 s − 1 . All of these make this system promising for scalable quantum information applications. Furthermore, we investigate the effects of contaminant Rydberg excitations on the source efficiency and observed single-mode efficiencies up to 0.18(2) for lower photon rates. Finally, recognizing that many quantum information protocols require a single photon in a fully single mode, we introduce metrics that take into account all degrees of freedom to benchmark the performance of on-demand sources.

Advances in the distribution of quantum information will likely require entanglement shared across a hybrid quantum network. Many entanglement protocols require the generation of indistinguishable photons between the various nodes of the network. This is challenging in a hybrid environment due to typically large differences in the spectral and temporal characteristics of single photons generated in different systems. Here we show, for the first time, quantum interference between photons generated from a single atomic ion and an atomic ensemble, located in different buildings and linked via optical fibre. Trapped ions are leading candidates for quantum computation and simulation with good matter-to-photon conversion. Rydberg excitations in neutral-atom ensembles show great promise as interfaces for the storage and manipulation of photonic qubits with excellent efficiencies. Our measurement of high-visibility interference between photons generated by these two, disparate systems is an important building block for the establishment of a hybrid quantum network.

Quantum simulations with ultracold atoms typically create atomic wavefunctions with structures at optical length scales, where direct imaging suffers from the diffraction limit. In analogy to advances in optical microscopy for biological applications, we use a non-linear atomic response to surpass the diffraction limit. Exploiting quantum interference, we demonstrate imaging with super-resolution of λ/50 and excellent temporal resolution of 500 ns. We characterize our microscope's performance by measuring the ensemble averaged probability density of atoms within the unit cells of an optical lattice, and observe the dynamics of atoms excited into motion. This approach can be readily applied to image any atomic or molecular system, as long as it hosts a three-level system.

A scheme to achieve Bose-Einstein condensation of photons through the Doppler cooling of an atomic ensemble is proposed. Interesting features of the approach include a controllable chemical potential and energy-dependent loss mechanisms.

We experimentally investigate the effects of parametric instabilities on the short-time heating process of periodically driven bosons in 2D optical lattices with a continuous transverse (tube) degree of freedom. We analyze three types of periodic drives: (i) linear along the x-lattice direction only, (ii) linear along the lattice diagonal, and (iii) circular in the lattice plane. In all cases, we demonstrate that the Bose-Einstein condensate (BEC) decay is dominated by the emergence of unstable Bogoliubov modes, rather than scattering in higher Floquet bands, in agreement with recent theoretical predictions. The observed BEC depletion rates are much higher when shaking along both the x and y directions, as opposed to only x or only y. We also report an explosion of the decay rates at large drive amplitudes and suggest a phenomenological description beyond the Bogoliubov theory. In this strongly coupled regime, circular drives heat faster than diagonal drives, which illustrates the nontrivial dependence of the heating on the choice of drive., SCOPUS: ar.j, info:eu-repo/semantics/published

We generalize past work on quantum sensor networks to show that, for $d$ input parameters, entanglement can yield a factor $\mathcal O(d)$ improvement in mean squared error when estimating an analytic function of these parameters. We show that the protocol is optimal for qubit sensors, and conjecture an optimal protocol for photons passing through interferometers. Our protocol is also applicable to continuous variable measurements, such as one quadrature of a field operator. We outline a few potential applications, including calibration of laser operations in trapped ion quantum computing., 10 pages, 2 figures, v2: updated to published version

Floquet engineering or coherent time-periodic driving of quantum systems has been successfully used to synthesize Hamiltonians with novel properties. In ultracold atomic systems, this has led to experimental realizations of artificial gauge fields, topological bandstructures, and observation of dynamical localization, to name a few. Here we present a Floquet-based framework to stroboscopically engineer Hamiltonians with spatial features and periodicity below the diffraction limit of light used to create them by time-averaging over various configurations of a 1D optical Kronig–Penney (KP) lattice. The KP potential is a lattice of narrow subwavelength barriers spaced by half the optical wavelength (λ/2) and arises from the nonlinear optical response of the atomic dark state. Stroboscopic control over the strength and position of this lattice requires time-dependent adiabatic manipulation of the dark-state spin composition. We investigate adiabaticity requirements and shape our time-dependent light fields to respect the requirements. We apply this framework to show that a λ/4-spaced lattice can be synthesized using realistic experimental parameters as an example, discuss mechanisms that limit lifetimes in these lattices, explore candidate systems and their limitations, and treat adiabatic loading into the ground band of these lattices.

Optical lattices are typically created via the ac Stark shift and are limited by diffraction to periodicities $\ensuremath{\ge}\ensuremath{\lambda}/2$, where $\ensuremath{\lambda}$ is the wavelength of light used to create them. Lattices with smaller periodicities may be useful for many-body physics with cold atoms and can be generated by stroboscopic application of a phase-shifted lattice with subwavelength features. Here we demonstrate a $\ensuremath{\lambda}/4$-spaced lattice by stroboscopically applying optical Kronig-Penney-like potentials which are generated using spatially dependent dark states. We directly probe the periodicity of the $\ensuremath{\lambda}/4$-spaced lattice by measuring the average probability density of the atoms loaded into the ground band of the lattice. We measure lifetimes of atoms in this lattice and discuss the mechanisms that limit the applicability of this stroboscopic approach.

Laser cooling of atomic motion enables a wide variety of technological and scientific explorations using cold atoms. Here we focus on the effect of laser cooling on the photons instead of on the atoms. Specifically, we show that non-interacting photons can thermalize with the atoms to a grand canonical ensemble with a non-zero chemical potential. This thermalization is accomplished via scattering of light between different optical modes, mediated by the laser cooling process. While optically thin modes lead to traditional laser cooling of the atoms, the dynamics of multiple scattering in optically thick modes has been more challenging to describe. We find that in an appropriate set of limits, multiple scattering leads to thermalization of the light with the atomic motion in a manner that approximately conserves total photon number between the laser beams and optically thick modes. In this regime, the subsystem corresponding to the thermalized modes is describable by a grand canonical ensemble with a chemical potential set by the energy of a single laser photon. We consider realization of this regime using two-level atoms in Doppler cooling, and find physically realistic conditions for rare earth atoms. With the addition of photon-photon interactions, this system could provide a new platform for exploring many-body physics., 13 pages, 5 figures

We propose an experimental scheme to construct an optical lattice where the atoms are confined to the surface of a torus. This construction can be realized with spatially shaped laser beams which could be realized with recently developed high resolution imaging techniques. We numerically study the feasibility of this proposal by calculating the tunneling strengths for atoms in the torus lattice. To illustrate the non-trivial role of topology in atomic dynamics on the torus, we study the quantized superfluid currents and fractional quantum Hall (FQH) states on such a structure. For FQH states, we numerically investigate the robustness of the topological degeneracy and propose an experimental way to detect such a degeneracy. Our scheme for torus construction can be generalized to Riemann surfaces with higher genus for exploration of richer topological physics., 5+8 pages, 4+5 figures

We study theoretically and experimentally the competing blockade and anti-blockade effects induced by spontaneously generated contaminant Rydberg atoms in driven Rydberg systems. These contaminant atoms provide a source of strong dipole-dipole interactions and play a crucial role in the system's behavior. We study this problem theoretically using two different approaches. The first is a cumulant expansion approximation, in which we ignore third-order and higher connected correlations. Using this approach for the case of resonant drive, a many-body blockade radius picture arises, and we find qualitative agreement with previous experimental results. We further predict that as the atomic density is increased, the Rydberg population's dependence on Rabi frequency will transition from quadratic to linear dependence at lower Rabi frequencies. We study this behavior experimentally by observing this crossover at two different atomic densities. We confirm that the larger density system has a smaller crossover Rabi frequency than the smaller density system. The second theoretical approach is a set of phenomenological inhomogeneous rate equations. We compare the results of our rate equation model to the experimental observations in [E. A. Goldschmidt, et al., PRL 116, 113001 (2016)] and find that these rate equations provide quantitatively good scaling behavior of the steady-state Rydberg population for both resonant and off-resonant drive., 16 pages, 13 figures

Simulating magnetism out of equilibrium A major goal of quantum simulation is to help us understand problems that are difficult to describe analytically or solve with conventional computers. This goal has been very challenging to reach experimentally, requiring, for example, extremely low temperatures to determine the effects of quantum magnetism in equilibrium. Brown et al. studied a nonequilibrium system of ultracold 87 Rb atoms in a two-dimensional optical lattice. They monitored the atoms' dynamics after a sudden change in the lattice parameters and were able to reach a regime where the magnetic interactions dominated the dynamics. Science , this issue p. 540

Strong dipole-exchange interactions due to spontaneously produced contaminant states can trigger rapid dephasing in many-body Rydberg ensembles [E. Goldschmidt et al., PRL 116, 113001 (2016)]. Such broadening has serious implications for many proposals to coherently use Rydberg interactions, particularly Rydberg dressing proposals. The dephasing arises as a runaway process where the production of the first contaminant atoms facilitates the creation of more contaminant atoms. Here we study the time dependence of this process with stroboscopic approaches. Using a pump-probe technique, we create an excess "pump" Rydberg population and probe its effect with a different "probe" Rydberg transition. We observe a reduced resonant pumping rate and an enhancement of the excitation on both sides of the transition as atoms are added to the pump state. We also observe a timescale for population growth significantly shorter than predicted by homogeneous mean-field models, as expected from a clustered growth mechanism where high-order correlations dominate the dynamics. These results support earlier works and confirm that the time scale for the onset of dephasing is reduced by a factor which scales as the inverse of the atom number. In addition, we discuss several approaches to minimize these effects of spontaneous broadening, including stroboscopic techniques and operating at cryogenic temperatures. It is challenging to avoid the unwanted broadening effects, but under some conditions they can be mitigated., 12 pages, 8 figures

A major application for atomic ensembles consists of a quantum memory for light, in which an optical state can be reversibly converted to a collective atomic excitation on demand. There exists a well-known fundamental bound on the storage error, when the ensemble is describable by a continuous medium governed by the Maxwell-Bloch equations. The validity of this model can break down, however, in systems such as dense, ordered atomic arrays, where strong interference in emission can give rise to phenomena such as subradiance and "selective" radiance. Here, we develop a general formalism that finds the maximum storage efficiency for a collection of atoms with discrete, known positions, and a given spatial mode in which an optical field is sent. As an example, we apply this technique to study a finite two-dimensional square array of atoms. We show that such a system enables a storage error that scales with atom number $N_\mathrm{a}$ like $\sim (\log N_\mathrm{a})^2/N_\mathrm{a}^2$, and that, remarkably, an array of just $4 \times 4$ atoms in principle allows for an efficiency comparable to a disordered ensemble with optical depth of around 600., Comment: paper is now identical to published version

We report on the experimental realization of a conservative optical lattice for cold atoms with sub-wavelength spatial structure. The potential is based on the nonlinear optical response of three-level atoms in laser-dressed dark states, which is not constrained by the diffraction limit of the light generating the potential. The lattice consists of a 1D array of ultra-narrow barriers with widths less than 10~nm, well below the wavelength of the lattice light, physically realizing a Kronig-Penney potential. We study the band structure and dissipation of this lattice, and find good agreement with theoretical predictions. The observed lifetimes of atoms trapped in the lattice are as long as 60 ms, nearly $10^5$ times the excited state lifetime, and could be further improved with more laser intensity. The potential is readily generalizable to higher dimension and different geometries, allowing, for example, nearly perfect box traps, narrow tunnel junctions for atomtronics applications, and dynamically generated lattices with sub-wavelength spacings., Comment: 5 pages, 4 figures, and supplementary material

We present a compact all-digital implementation of a scanning transfer cavity lock (STCL) for long-term laser frequency stabilization. An interrupt-driven state machine is employed to realize the STCL, with the capability to correct for frequency drifts in the slave laser frequency due to measured changes in the lab environmental conditions. We demonstrate an accuracy of 0.9 MHz for master laser and slave laser wavelengths of 556 nm and 798 nm as an example. The slave laser is also demonstrated to dynamically scan over a wide frequency range while retaining its lock, allowing us to accurately interrogate atomic transitions., Comment: 7 pages, 4 figures

We study experimentally the stability of excited, interacting states of bosons in a double-well optical lattice in regimes where the nonlinear interactions are expected to induce "swallowtail" looped band structure. By carefully preparing different initial coherent states and observing their subsequent decay, we observe distinct decay rates that provide direct evidence for multivalued, looped band structure. The double well lattice both stabilizes the looped band structure and allows for dynamic preparation of different initial states, including states within the loop structure. We confirm our state preparation procedure with dynamic Gross-Pitaevskii calculations. The excited loop states are found to be more stable than dynamically unstable ground states, but decay faster than expected based on a mean-field stability calculation, indicating the importance of correlations beyond a mean field description., 6 pages, 6 figures

Electromagnetism is a simple example of a gauge theory where the underlying potentials -- the vector and scalar potentials -- are defined only up to a gauge choice. The vector potential generates magnetic fields through its spatial variation and electric fields through its time-dependence. We experimentally produce a synthetic gauge field that emerges only at low energy in a rubidium Bose-Einstein condensate: the neutral atoms behave as charged particles do in the presence of a homogeneous effective vector potential. We have generated a synthetic electric field through the time dependence of an effective vector potential, a physical consequence even though the vector potential is spatially uniform.

We present a piezo-driven translatable mirror with excellent pointing stability, capable of driving at frequencies up to tens of kilohertz. Our system uses a tripod of piezo actuators with independently controllable drive voltages, where the ratios of the individual drive voltages are tuned to minimize residual tilting. Attached to a standard {\varnothing}= 12.7mm mirror, the system has a resonance-free mechanical bandwidth up to 51kHz, with displacements up to 2{\mu}m at 8kHz. The maximum static steering error is 5.5rad per micrometer displaced and the dynamic steering error is lower than 0.6rad/{\mu}m. This simple design should be useful for a large set of optical applications where tilt-free displacements are required, and we demonstrate its application in an ensemble of cold atoms trapped in periodically driven optical lattices.

We present experimental observations of the suppressed superfluid transition temperature, T ca , superfluid fraction, ρ s /ρ and Leggett frequency of 3He-B in aerogel, Ω Ba . We determine T ca from mass decoupling and the vanishing of the frequency shift away from the Larmor frequency in our different samples and different laboratories. We find that the suppressed transition temperature for 3He in aerogel occurs at a sample dependent, but approximately pressure independent, length, $X=\xi_{0}(P)/\sqrt{1-T_{\mathit{ca}}/T_{c}}$ , where T c and ξ 0(P), are the transition temperature and the pressure dependent zero temperature coherence length for bulk 3He. T ca also occurs at a pressure independent value of the Leggett frequency of bulk 3He-B. Further, we find that when the superfluid fraction and square of the Leggett frequency are plotted against T ca −T (and not (T ca −T)/T ca ), the results of each measurement nearly collapse on to a pressure independent but sample dependent plot, with no further scaling. When plotted on a log–log scale, both measurements exhibit power laws in the range 1.33–1.45.

Controlled two-particle interaction is a fundamental requirement for quantum computing, and achieving it has long been a goal for research on neutral atom systems. Anderlini et al. have used a system, consisting of arrays of paired ultracold rubidium-87 atoms in an optical lattice of double-well potentials, to induce controlled entangling interactions within each atom pair. Repeated interchange of spin between atoms occupying different vibrational levels occurs with a coherence time of more than ten milliseconds. This demonstrates an essential component of a quantum gate. An optical lattice of double-well potentials is used to isolate and manipulate arrays of paired 87Rb atoms, inducing controlled entangling interactions within each pair. Repeated interchange of spin between atoms occupying different vibrational levels occurs with a coherence time of more than ten milliseconds. This observation demonstrates the essential component of a quantum gate important for quantum computation. Ultracold atoms trapped by light offer robust quantum coherence and controllability, providing an attractive system for quantum information processing and for the simulation of complex problems in condensed matter physics. Many quantum information processing schemes require the manipulation and deterministic entanglement of individual qubits; this would typically be accomplished using controlled, state-dependent, coherent interactions among qubits. Recent experiments have made progress towards this goal by demonstrating entanglement among an ensemble of atoms1 confined in an optical lattice. Until now, however, there has been no demonstration of a key operation: controlled entanglement between atoms in isolated pairs. Here we use an optical lattice of double-well potentials2,3 to isolate and manipulate arrays of paired 87Rb atoms, inducing controlled entangling interactions within each pair. Our experiment realizes proposals to use controlled exchange coupling4 in a system of neutral atoms5. Although 87Rb atoms have nearly state-independent interactions, when we force two atoms into the same physical location, the wavefunction exchange symmetry of these identical bosons leads to state-dependent dynamics. We observe repeated interchange of spin between atoms occupying different vibrational levels, with a coherence time of more than ten milliseconds. This observation demonstrates the essential component of a neutral atom quantum SWAP gate (which interchanges the state of two qubits). Its ‘half-implementation’, the gate, is entangling, and together with single-qubit rotations it forms a set of universal gates for quantum computation4.

We report the first realization of a quantum degenerate mixture of bosonic $^{87}$Rb and fermionic $^{171}$Yb atoms in a hybrid optical dipole trap with a tunable, species-dependent trapping potential. $^{87}$Rb is shown to be a viable refrigerant for the non-interacting $^{171}$Yb atoms, cooling up to $2.4 \times 10^5$ $^{171}$Yb atoms to a temperature of $T/T_F = 0.16(2) $ while simultaneously forming a $^{87}$Rb BEC of $3.5 \times 10^5$ atoms. Furthermore we demonstrate our ability to independently tailor the potentials for each species, which paves the way for studying impurities immersed in a Bose gas., Comment: sumbitted to PRA 06-26-2015

Magic wavelengths, for which there is no differential ac Stark shift for the ground and excited state of the atom, allow trapping of excited Rydberg atoms without broadening the optical transition. This is an important tool for implementing quantum gates and other quantum information protocols with Rydberg atoms, and reliable theoretical methods to find such magic wavelengths are thus extremely useful. We use a high-precision all-order method to calculate magic wavelengths for the $5s-18s$ transition of rubidium, and compare the calculation to experiment by measuring the light shift for atoms held in an optical dipole trap at a range of wavelengths near a calculated magic value.

We observe interaction-induced broadening of the two-photon 5s-18s transition in 87Rb atoms trapped in a 3D optical lattice. The measured linewidth increases by nearly two orders of magnitude with increasing atomic density and excitation strength, with corresponding suppression of resonant scattering and enhancement of off-resonant scattering. We attribute the increased linewidth to resonant dipole-dipole interactions of 18s atoms with spontaneously created populations of nearby np states. Over a range of initial atomic densities and excitation strengths, the transition width is described by a single function of the steady-state density of Rydberg atoms, and the observed resonant excitation rate corresponds to that of a two-level system with the measured, rather than natural, linewidth. The broadening mechanism observed here is likely to have negative implications for many proposals with coherently interacting Rydberg atoms., Comment: 5+3 pages

We report on the experimental demonstration of dynamic control of the motional state of atoms in a 2D double-well optical lattice. First we describe experiments in which the atomic distributions obtained by loading Bose–Einstein condensates of rubidium atoms in the lattice are dynamically split by transforming a 2D lattice with period λ into a 2D lattice with period λ/2, and we show how this procedure allows for the study of the coherence and interaction properties of the system. Then we show how we can efficiently adiabatically transfer the population between adjacent sites of the lattice, as well as between different energy bands, by using dynamic modifications of the potential.

The loading of a Bose-Einstein condensate into a deep two-dimensional optical lattice provides a unique way to study one-dimensional Bose gases: the strong radial confinement freezes any motion in two dimensions, and for deep enough lattices, the system can be seen as an array of independent I D tubers. For our experimental parameters, the ID gas is predicted to be in an intermediate regime between the Tonks-Girardeau and the Thomas-Fermi regimes. We performed experiments showing that some long range phase coherence is present in this regime. We investigated correlation properties of these gases by studying their collective oscillations. In addition, we investigated the ID Mott transition by adiabatically loading the 1D gases into a 1D optical lattice.

One of the essential features of a quantum computer is a quantum 'register' of well-characterized qubits. Neutral atoms in optical lattices are a natural candidate for such a register. We have demonstrated a patterned-loading technique that can be used to load atoms into large arrays of tightly confined but optically resolvable lattice sites. We have also seen preliminary indications of the Mott-insulator transition, which provides a route for single-atom initialization of the individual sites. Combining the two experiments should allow for large arrays of individually addressable single atoms, a system which provides a starting point for further quantum computation studies.

Browman, Snider and Ellis propose that managers act as catalysts to institute structures for the negotiation of differences between managers and clinicians, primarily around the perceived trade-offs between quality care and resource allocation. Evidence-based medicine and evidence-based management are required to level the playing field, so that quality of care will not suffer "at the expense of the business agenda which is easier to measure and manage." But implementation of evidence-based management and evidence-based medicine depends on the quality of knowledge production and the ability to adapt general knowledge to particular organizations. Agreement on guidelines for evidence-based management is problematic and complicated by the nature of management research itself. Rather than the metaphor of the negotiating environment, which assumes an adversarial relationship between management and clinicians, a more fruitful metaphor is the expert environment, which assumes a collaborative relationship between the two. Management should not only be a catalyst for change but should also assume the responsibility of cultivating clinical and managerial expertise at all levels of the organization, from custodian to surgeon.

Greater economic benefits have been associated with longer lengths of stay in methadone treatment. Little is known about whether the costs and benefits of methadone treatment differ for women and men. This paper examines the costs of outpatient methadone treatment (OMT) in NIDA's Drug Abuse Treatment Outcome Studies (DATOS) for women and men, and estimates the economic benefits from avoided crime costs during and after treatment. Women and men are also grouped according to length of time in treatment and costs are examined for discharged patients (patients with less than 1 year of treatment in their index DATOS OMT program) and continuing patients (patients who remained in their index treatment for at least 1 year). It was hypothesized that methadone treatment benefits in the form of costs of crime to society before, during, and after treatment would differ by gender, and crime cost savings would be greater for both women and men who remained in treatment for 365 days or longer. Subjects were 144...

Longer lengths of stay in methadone treatment have been associated with greater treatment benefits such as reductions in heroin use and criminal activity. In this paper, the first of two concentrating on costs of methadone treatment, the positive monetary returns from investments in longer-term methadone treatment for opioid users who participated in NIDA's Drug Abuse Treatment Outcome Studies (DATOS) are demonstrated. Part 1 focuses on crime cost savings for discharged patients (patients who left their index DATOS treatment program before completing 1 year of treatment) and continuing patients (those who continued in treatment for 1 year or longer). It was hypothesized that methadone treatment benefits from tangible crime cost savings during treatment and at follow-up would be greater for the continuing patients. Subjects were 394 methadone patients from 8 medium to large cities and 16 programs; overall 37% were women, 33% African American, with an average age of 37.2. Results supported the hypo...

Ultracold molecular gases are promising as an avenue to rich many-body physics, quantum chemistry, quantum information, and precision measurements. This richness, which flows from the complex internal structure of molecules, makes the creation of ultracold molecular gases using traditional methods (laser plus evaporative cooling) a challenge, in particular due to the spontaneous decay of molecules into dark states. We propose a way to circumvent this key bottleneck using an all-optical method for decelerating molecules using stimulated absorption and emission with a single ultrafast laser. We further describe single-photon cooling of the decelerating molecules that exploits their high dark state pumping rates, turning the principal obstacle to molecular laser cooling into an advantage. Cooling and deceleration may be applied simultaneously and continuously to load molecules into a trap. We discuss implementation details including multi-level numerical simulations of strontium monohydride (SrH). These techniques are applicable to a large number of molecular species and atoms with the only requirement being an electric dipole transition that can be accessed with an ultrafast laser., 9 pages, 5 figures, 1 table

We report new observations of emission line intensity ratios of Fe XVII under controlled experimental conditions, using the National Institute of Standards and Technology electron beam ion trap (EBIT) with a microcalorimeter detector. We compare our observations with collisional-radiative models using atomic data computed in distorted wave and R-matrix approximations, which follow the transfer of the polarization of level populations through radiative cascades. Our results for the intensity ratio of the 2p6 1S0-2p53d 1P1 15.014 A line to the 2p6 1S0-2p53d 3D1 15.265 A line are 2.94 ± 0.18 and 2.50 ± 0.13 at beam energies of 900 and 1250 eV, respectively. These results are not consistent with collisional-radiative models and support conclusions from earlier EBIT work at the Lawrence Livermore National Laboratory that the degree of resonance scattering in the solar 15.014 A line has been overestimated in previous analyses. Further observations assess the intensity ratio of the three lines between the 2p6-2p53s configurations to the three lines between the 2p6-2p53d configurations. Both R-matrix and distorted wave approximations agree with each other and our experimental results much better than most solar and stellar observations, suggesting that other processes not present in our experiment must play a role in forming the Fe XVII spectrum in solar and astrophysical plasmas.

We have directly observed the ion cloud distribution in an electron beam ion trap using visible and ultraviolet fluorescence from lines in the ground term of Ar13+, Xe31+ and Xe32+ ions. Using a gated intensified charge coupled device camera, we have the capability to measure both static and dynamic ion cloud distributions. The images provide information about the trapped highly charged ions which is difficult to obtain by other methods. To demonstrate the usefulness of the technique, we took images of static ion clouds under different conditions and compared the distributions to a simple model. We also recorded time resolved images which show that we can monitor the relaxation of the ion cloud toward equilibrium when the trapping conditions are suddenly changed. The information provided by such measurements can be used to improve models of ion cloud dynamics and, combined with modeling, these techniques can help improve measurements of atomic data using electron beam ion traps.

Aerogels introduce disorder into the p-wave-paired superfluid 3 He and suppress Tc. Quantifiable (by small angle X-ray scattering) differences in the long-range structure of two identical density aerogels are primarily responsible for their different transition temperatures. We also demonstrate that alteration of the short-range correlations by the addition of 4 He does not strongly affect Tc. Acoustic measurements of the fast and slow modes of 3 He in aerogel are described. These can be used to explore the superfluid component. We also outline future prospects.

With the ability to create cosmic plasma conditions in the laboratory it is possible to investigate the dependencies of key diagnostic X-ray lines on density, temperature, and excitation conditions that exist in astrophysical sources with X-ray optics and a high-resolution X-ray microcalorimeter. The same instrumentation can be coupled to scanning electron microscopes or X-ray fluorescence probes to analyze the elemental and chemical composition of electronic, biological, geological and particulate materials. We describe how our microcalorimeter and X-ray optics provide significantly improved capabilities for laboratory astrophysics and microanalysis.

We have investigated the superfluid transition of 3 He in different samples of silica aerogel. Several of these samples have been characterized using x-ray imaging, yielding information about the microstructure of the aerogel. In comparing new measurements on a 99.5% sample with previous observations on the behavior of 3 He in 98% porous aerogel we have found evidence for a scaling of the superfluid transition temperature to the correlation length of the aerogel. Furthermore, the superfluid density exhibits a similar universal behaviour over a range of values of reduced temperature. We discuss these new results in the context of superfluid pairing in the presence of a correlated disorder, specifically focussing on the fractal nature of the aerogel.

We report new values from Penning trap single ion mass spectrometry for the atomic masses of ${}^{133}\mathrm{Cs}$, ${}^{87}\mathrm{Rb}$, ${}^{85}\mathrm{Rb}$, and ${}^{23}\mathrm{Na}$ with uncertainties $\ensuremath{\le}0.2\mathrm{ppb}$, a factor of 100 improvement over the accuracy of previously measured values. We have found $M{(}^{133}\mathrm{Cs})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}132.905451931(27)u$, $M{(}^{87}\mathrm{Rb})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}86.909180520(15)u$, $M{(}^{85}\mathrm{Rb})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}84.911789732(14)u$, and $M{(}^{23}\mathrm{Na})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}22.9897692807(28)u$. These values are important for new ppb-level determinations of the molar Planck constant ${N}_{A}h$ and the fine-structure constant \ensuremath{\alpha}. With the measurement of ${}^{133}\mathrm{Cs}$ we have increased the mass range for sub-ppb measurements by a factor of 3. From $M{(}^{133}\mathrm{Cs})$ and other values we derive ${\ensuremath{\alpha}}^{\ensuremath{-}1}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}137.0359922(40)$.

The role of aerogel as a means of introducing correlated disorder into superfluid ${}^{3}\mathrm{He}$ is examined in this paper. The aerogel structure is described by a diffusion-limited cluster aggregation model and compared to the results of small-angle x-ray scattering obtained from samples that were used to study the suppression of ${T}_{c}$ as well as the development of the superfluid fraction. These results highlight special characteristics of aerogels that make this medium appropriate as a means of introducing disorder into ${}^{3}\mathrm{He}.$ We discuss the inapplicability of the Abrikosov-Gorkov model of an impure superconductor to the ${}^{3}\mathrm{He}$-aerogel system, and then detail the behavior of ${T}_{c}$ and the superfluid fraction of ${}^{3}\mathrm{He}$ contained in three different samples of aerogel.

We have examined the superfluidity of ${}^{3}\mathrm{He}$ in 98.2% porous silica aerogel with up to 34% ${}^{4}\mathrm{He}$ at 21.6 bars. The mixture is phase separated for ${}^{4}\mathrm{He}$ fractions between $\ensuremath{\sim}11%$ and 34%, and the ${}^{4}\mathrm{He}$-rich phase preferentially occupies the regions of highest silica density in the aerogel, thus modifying the distribution of the correlated disorder seen by superfluid ${}^{3}\mathrm{He}$. The ${}^{3}\mathrm{He}$ ${T}_{c}$ increases slightly with ${}^{4}\mathrm{He}$ content while the superfluid fraction decreases rapidly. This behavior is inconsistent with that of ${}^{3}\mathrm{He}$ in a homogeneously scattering medium and is analogous to that of a granular superconductor.

We describe new torsional oscillator experiments on3He confined in 98.2% open aerogel. In one, we monitored the superfluid fraction of pure3He at T << Tcwhile we gradually changed the sample pressure. The resulting change in density alters ξ0of the superfluid3He relative to the distribution of the length scales (correlations) of silica in the aerogel. We observed a T = 0 normal-to-super fluid transition at a pressure of about 6.5 bar, in marked contrast to the bulk where liquid3He is superfluid at all pressures. In the second experiment, we measured the temperature dependence of the3He ρsat a pressure of 21.6 bar with different amounts of4He present in the cell. Adding 2-3%4He slightly increases both Tcand ρs. We found that for4He concentrations between 2% and 34%, the3He Tcincreases by a very small amount. However, ρs, which for pure3He in aerogel at 0.5Tcis no more than 11%, falls by another factor of 7. This behavior (constant Tc, reduced ρs) is similar to that observed in granular superconducting films where the long-range order is controlled by phase coherence between adjacent grains.

We have studied details of the phase separation of3He-4He mixtures in aerogel for4He concentrations between 13 - 36% and at pressures of 0 and 22 bar. Simultaneous measurements of the4He concentration (measured with a parallel-plate capacitor) and of the tortuosity of the4He-rich phase (using the period of the torsional oscillator) provide evidence for the diversity of configurations of the3He-4He interface as a consequence of capillary condensation. Thus, for the same4He content within the aerogel, the4He-rich phase can have different interconnectivities determined by preparation history.

We have used a torsional oscillator to measure the superfluid density and dissipation near the superfluid transition of 3 He in aerogel of 99.5% porosity. We used a new cell (constructed at Penn State) for which the aerogel was grown in the pores of a ∼100 μm silver sinter. The cell was tested with 4 He and showed no signs of the second-sound resonances that have interfered with previous torsional oscillator measurements. The measurements with 3 He, presented here, were taken at pressures of 1.34 and 4.13 bars. We observed values of ρ s /ρ in the T→ 0 limit of 0.05 and 0.14 respectively. Our measurements show an increase in the dissipation on warming through T c . This series of measurements is ongoing and temperature sweeps at various pressures are planned.

We present evidence for a nonzero pressure, T=0 superfluid phase transition of {sup 3}He in 98.2{percent} open aerogel. Unlike bulk {sup 3}He, which is a superfluid at T=0 at all pressures (densities) between zero and the melting pressure, {sup 3}He in aerogel is not superfluid unless the {sup 3}He density exceeds a critical value {rho}{sub c} . About 90{percent} of the {sup 3}He added above {rho}{sub c} contributes to the superfluid density. {copyright} {ital 1997} {ital The American Physical Society}

We present two complementary designs of pneumatically actuated and kinematically positioned optics mounts: one designed for vertical mounting and translation, the other designed for horizontal mounting and translation. The design and measured stability make these mounts well-suited to experiments with laser-cooled atoms.

We characterize the effect of quantum interference on the line shapes and measured line positions in atomic spectra. These effects, which occur when the excited state splittings are of order the excited state line widths, represent an overlooked but significant systematic effect. We show that excited state interference gives rise to non-Lorenztian line shapes that depend on excitation polarization, and we present expressions for the corrected line shapes. We present spectra of 6,7 Li D lines taken at multiple excitation laser polarizations and show that failure to account for interference changes the inferred line strengths and shifts the line centers by as much as 1 MHz. Using the correct lineshape, we determine absolute optical transition frequencies with an uncertainty of