Results for "Morgan W. Mitchell"

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NOON states from cavity-enhanced down-conversion: High quality and super-resolutionNov 27 2009Indistinguishable photons play a key role in quantum optical information technologies. We characterize the output of an ultra-bright photon-pair source using multi-particle tomography [R. B. A. Adamson et al., Phys. Rev. Lett. 98, 043601 (2007)] and separately ... More
Signal tracking beyond the time resolution of an atomic sensor by Kalman filteringJul 25 2017Feb 21 2018We study causal waveform estimation (tracking) of time-varying signals in a paradigmatic atomic sensor, an alkali vapor monitored by Faraday rotation probing. We use Kalman filtering, which optimally tracks known linear Gaussian stochastic processes, ... More
Sensitivity, quantum limits, and quantum enhancement of noise spectroscopiesOct 07 2016May 15 2018We study the fundamental limits of noise spectroscopy using estimation theory, Faraday rotation probing of an atomic spin system, and squeezed light. We find a simple and general expression for the Fisher information, which quantifies the sensitivity ... More
Spatial entanglement of paired photons generated in cold atomic ensemblesApr 21 2008Jul 24 2008Cold atomic ensembles can mediate the generation of entanglement between pairs of photons. Photons with specific directions of propagation are detected, and the entanglement can reside in any of the degrees of freedom that describe the whole quantum state ... More
Optimal Signal Recovery for Pulsed Balanced DetectionMar 27 2014May 16 2015We demonstrate a new tool for filtering technical and electronic noises from pulses of light, especially relevant for signal processing methods in quantum optics experiments as a means to achieve the shot-noise level and reduce strong technical noise ... More
Strong light shifts from near-resonant and polychromatic fields: comparison of Floquet theory and experimentFeb 09 2017We present a non-perturbative numerical technique for calculating strong light shifts in atoms under the influence of multiple optical fields with arbitrary polarization. We confirm our technique experimentally by performing spectroscopy of a cloud of ... More
Measurement-induced nonlocal entanglement in a hot, strongly-interacting atomic systemApr 20 2018Quantum entanglement underlies quantum technologies, and is notoriously sensitive to decohering processes. For this reason, many implementations take elaborate measures to remove entropy from their environments, e.g. cryogenics or optical cooling to reach ... More
Squeezed-light spin noise spectroscopySep 18 2015May 10 2016We report quantum enhancement of Faraday rotation spin noise spectroscopy by polarization squeezing of the probe beam. Using natural abundance Rb in 100 Torr of N_2 buffer gas, and squeezed light from a sub-threshold optical parametric oscillator stabilized ... More
Maltese cross coupling to cold atoms in free spaceFeb 08 2019We demonstrate a novel geometry for strong coupling of light and matter in free space, i.e., without the use of optical cavities. Guided by optical metrology tools, we use a manual pick-and-place technique to precisely and stably position four high numerical ... More
Electric field excitation suppression in cold atomsApr 22 2019In this article, the atom excitation suppression is studied in two ways. The first way of exploring the excitation suppression is by an external DC electric field. The second way is to study the excitation suppression caused by electric field generated ... More
Polarization-based Light-Atom Quantum Interface with an All-optical TrapDec 29 2008Feb 23 2009We describe the implementation of a system for studying light-matter interactions using an ensemble of $10^6$ cold rubidium 87 atoms, trapped in a single-beam optical dipole trap. In this configuration the elongated shape of the atomic cloud increases ... More
Absolute frequency references at 1529 nm and 1560 nm using modulation transfer spectroscopySep 22 2015We demonstrate a double optical frequency reference (1529 nm and 1560 nm) for the telecom C-band using $^{87}$Rb modulation transfer spectroscopy. The two reference frequencies are defined by the 5S$_{1/2} F=2 \rightarrow $ 5P$_{3/2} F'=3$ two-level and ... More
Generation, characterization and use of atom-resonant indistinguishable photon pairsFeb 26 2015We describe the generation of atom-resonant indistinguishable photon pairs using nonlinear optical techniques, their spectral purification using atomic filters, characterization using multi-photon interference, and application to quantum-enhanced sensing ... More
Sensor self-interaction, scale-invariant spin dynamics, and the $\hbar$ limit of field sensingApr 02 2019We describe quantum limits to field sensing that relate noise, geometry and measurement duration to fundamental constants, with no reference to particle number. We cast the Tesche and Clarke (TC) bound on dc-SQUID sensitivity as such a limit, and find ... More
Parametric down-conversion from a wave-equations approach: geometry and absolute brightnessJul 22 2008Jan 25 2009Using the approach of coupled wave equations, we consider spontaneous parametric down-conversion (SPDC) in the narrow-band regime and its relationship to classical nonlinear processes such as sum-frequency generation. We find simple expressions in terms ... More
Experimental test of measurement dependent local Bell inequality with human free willJul 02 2018A Bell test can rule out local realistic models, and has potential applications in communications and information tasks. For example, a Bell inequality violation can certify the presence of intrinsic randomness in measurement outcomes, which then can ... More
Entangled photon apparatus for the undergraduate laboratoryMay 27 2002We present detailed instructions for constructing and operating an apparatus to produce and detect polarization-entangled photons. The source operates by type-I spontaneous parametric downconversion in a two-crystal geometry. Photons are detected in coincidence ... More
Entangled photons, nonlocality and Bell inequalities in the undergraduate laboratoryMay 27 2002We use polarization-entangled photon pairs to demonstrate quantum nonlocality in an experiment suitable for advanced undergraduates. The photons are produced by spontaneous parametric downconversion using a violet diode laser and two nonlinear crystals. ... More
Generation of macroscopic singlet states in atomic ensemblesJan 27 2009May 19 2010We study squeezing of the spin uncertainties by quantum non-demolition (QND) measurement in non-polarized spin ensembles. Unlike the case of polarized ensembles, the QND measurements can be performed with negligible back-action, which allows, in principle, ... More
Spontaneous PT symmetry breaking of a ferromagnetic superfluid in a gradient fieldJan 27 2015Sep 24 2015We consider the interaction of a ferromagnetic spinor Bose-Einstein condensate with a magnetic field gradient. The magnetic field gradient realizes a spin-position coupling that explicitly breaks time-reversal symmetry T and space parity P, but preserves ... More
A magneto-optical trap created by the 2nd-order external cavity diode lasersDec 03 2018In this article, we report on a magneto-optical trap (MOT) created by the 2nd-order external cavity diode lasers (ECDLs). The lasers were characterized. We have observed the non-continuous changes of the wavelength as a function of the laser diode current. ... More
Standing Swells Surveyed Showing Surprisingly Stable Solutions for the Lorenz '96 ModelDec 20 2013Jul 16 2014The Lorenz '96 model is an adjustable dimension system of ODEs exhibiting chaotic behavior representative of dynamics observed in the Earth's atmosphere. In the present study, we characterize statistical properties of the chaotic dynamics while varying ... More
Constructing a taxonomy of fine-grained human movement and activity motifs through social mediaSep 28 2014May 11 2015Profiting from the emergence of web-scale social data sets, numerous recent studies have systematically explored human mobility patterns over large populations and large time scales. Relatively little attention, however, has been paid to mobility and ... More
Atom-resonant squeezed light from a tunable monolithic ppRKTP parametric amplifierJan 06 2018We demonstrate vacuum squeezing at the D1 line of atomic rubidium (795 nm) with a tunable, doubly-resonant, monolithic sub-threshold optical parametric oscillator in periodically-poled Rb-doped potassium titanyl phosphate. The squeezing appears to be ... More
Quantum limits to the energy resolution of magnetic field sensorsMay 02 2019The energy resolution per bandwidth $E_R$ is a figure of merit that combines the field resolution, bandwidth or duration of the measurement, and size of the sensed region. Several very different dc magnetometer technologies approach $E_R = \hbar$, while ... More
Strong experimental guarantees in ultrafast quantum random number generationJan 13 2015We describe a methodology and standard of proof for experimental claims of quantum random number generation (QRNG), analogous to well-established methods from precision measurement. For appropriately constructed physical implementations, lower bounds ... More
Theory of high gain cavity-enhanced spontaneous parametric down-conversionSep 03 2014Jan 08 2015We compute the output of multimode cavity-enhanced spontaneous parametric down-conversion (SPDC) for sub-threshold, but otherwise arbitrary, gain. We find analytic Bogoliubov transformations that allow us to calculate arbitrary field correlation functions, ... More
A self-tuning optical resonatorJul 28 2017Jan 06 2018We demonstrate a nonlinear optical resonator that tunes itself onto resonance with an input beam. In a monolithic Fabry-Perot cavity implemented in rubidium-doped periodically-poled potassium titanyl phosphate, an intensity-dependent refractive index ... More
Extreme spin squeezing for photonsApr 09 2013Jun 10 2014We apply spin-squeezing techniques to identify and quantify highly multi-partite photonic entanglement in polarization-squeezed light. We consider a practical single-mode scenario, and find that Wineland-criterion polarization squeezing implies entanglement ... More
Optical spin squeezing: bright beams as high-flux entangled photon sourcesMar 21 2013Oct 09 2013In analogy with the spin-squeezing inequality of Wang and Sanders [Physical Review A 68, 012101 (2003)], we find inequalities describing macroscopic polarization correlations that are obeyed by all classical fields, and whose violation implies entanglement ... More
Significant-loophole-free test of Bell's theorem with entangled photonsNov 10 2015Dec 20 2015Local realism is the worldview in which physical properties of objects exist independently of measurement and where physical influences cannot travel faster than the speed of light. Bell's theorem states that this worldview is incompatible with the predictions ... More
A hierarchical network approach for modeling Rift Valley fever epidemics with applications in North AmericaOct 07 2011Feb 22 2013Rift Valley fever is a vector-borne zoonotic disease which causes high morbidity and mortality in livestock. In the event Rift Valley fever virus is introduced to the United States or other non-endemic areas, understanding the potential patterns of spread ... More
Multispin correlations and pseudo-thermalization of the transient density matrix in solid-state NMR: free induction decay and magic echoMay 31 2012Aug 16 2012Quantum unitary evolution typically leads to thermalization of generic interacting many-body systems. There are very few known general methods for reversing this process, and we focus on the magic echo, a radio-frequency pulse sequence known to approximately ... More
Universal Long-time Behavior of Nuclear Spin Decays in a SolidMay 13 2008Magnetic resonance studies of nuclear spins in solids are exceptionally well suited to probe the limits of statistical physics. We report experimental results indicating that isolated macroscopic systems of interacting nuclear spins possess the following ... More
Novel Dynamical Resonances in Finite-Temperature Bose-Einstein CondensatesMar 23 2005We describe a variety of intriguing mode-coupling effects which can occur in a confined Bose-Einstein condensed system at finite temperature. These arise from strong interactions between a condensate fluctuation and resonances of the thermal cloud yielding ... More
Ground State Quantum ComputationAug 11 1999We formulate a novel ground state quantum computation approach that requires no unitary evolution of qubits in time: the qubits are fixed in stationary states of the Hamiltonian. This formulation supplies a completely time-independent approach to realizing ... More
Modeling crater formation in femtosecond-pulse laser damage from basic principlesFeb 26 2015We present the first fundamental simulation method for the determination of crater morphology due to femtosecond-pulse laser damage. To this end we have adapted the particle-in-cell (PIC) method commonly used in plasma physics for use in the study of ... More
Characterisation of the ionosphere above the Murchison Radio Observatory using the Murchison Widefield ArrayJul 17 2017We detail new techniques for analysing ionospheric activity, using Epoch of Reionisation (EoR) datasets obtained with the Murchison Widefield Array (MWA), calibrated by the `Real-Time System' (RTS). Using the high spatial- and temporal-resolution information ... More
A passive transmitter for quantum key distribution with coherent lightAug 03 2011Signal state preparation in quantum key distribution schemes can be realized using either an active or a passive source. Passive sources might be valuable in some scenarios; for instance, in those experimental setups operating at high transmission rates, ... More
Shot-noise-limited magnetometer with sub-pT sensitivity at room temperatureMar 30 2014Nov 20 2014We report a photon shot-noise-limited (SNL) optical magnetometer based on amplitude modulated optical rotation using a room-temperature $^{85}$Rb vapor in a cell with anti-relaxation coating. The instrument achieves a room-temperature sensitivity of $70$ ... More
Requirements for a loophole-free photonic Bell test using imperfect setting generatorsNov 18 2014Mar 10 2016Experimental violations of Bell inequalities are in general vulnerable to so-called "loopholes." In this work, we analyse the characteristics of a loophole-free Bell test with photons, closing simultaneously the locality, freedom-of-choice, fair-sampling ... More
Planar squeezing by quantum non-demolition measurement in cold atomic ensemblesNov 20 2012May 05 2013Planar squeezed states, i.e. quantum states which are squeezed in two orthogonal spin components, have recently attracted attention due to their applications in atomic interferometry and quantum information [Q. Y. He et al, New J. Phys. 14, 093012 (2012)]. ... More
A tunable narrowband entangled photon pair source for resonant single-photon single-atom interactionAug 14 2008Aug 28 2008We present a tunable, frequency-stabilized, narrow-bandwidth source of frequency-degenerate, entangled photon pairs. The source is based on spontaneous parametric downconversion (SPDC) in periodically-poled KTiOPO4 (PPKTP). Its wavelength can be stabilized ... More
Self-lensing Discovery of a $0.2\,M_\odot$ White Dwarf in an Unusually Wide Orbit Around a Sun-like StarJul 17 2019Aug 11 2019We report the discovery of the fifth self-lensing binary in which a low-mass white dwarf (WD) gravitationally magnifies its 15th magnitude G-star companion, KIC 8145411, during eclipses. The system was identified from a pair of such self-lensing events ... More
The Relativistic Astrophysics Explorer: A New Mission for X-Ray TimingNov 11 1999The great success of the Rossi X-Ray Timing Explorer (RXTE) has given us a new probe to study strong gravitational fields and to measure the physical properties of black holes and neutron stars. Here, we describe a "next-generation" x-ray timing mission, ... More
X-Ray Observations of GRS 1915+105Sep 16 1996A comparison of ROSAT observations with simultaneous BATSE monitoring data shows a different intensity evolution in the soft and hard X-ray band of GRS 1915+105 since 1992. In addition, fits of simultaneous ROSAT/BATSE spectra require more than one spectral ... More
Measuring the Innermost Stable Circular Orbits of Supermassive Black HolesSep 29 2016Feb 01 2017We present a promising new technique, the g-distribution method, for measuring the inclination angle (i), the innermost stable circular orbit (ISCO), and the spin of a supermassive black hole. The g-distribution method uses measurements of the energy ... More
Spatial Models of Vector-Host Epidemics with Directed Movement of Vectors Over Long DistancesSep 10 2018We investigate a time-dependent spatial vector-host epidemic model with non-coincident domains for the vector and host populations. The host population resides in small non-overlapping sub-regions, while the vector population resides throughout a much ... More
Cuntz-Pimsner Algebras Associated to Tensor Products of CorrespondencesOct 16 2015Given two correspondences X and Y, we show that (under mild hypotheses) the Cuntz-Pimsner algebra of the tensor product of X and Y embeds as a certain subalgebra of the tensor product of the Cuntz-Pimsner algebra of X and the Cuntz=Pimsner algebra of ... More
On an extension of Galligo's theorem concerning the Borel-fixed points on the Hilbert schemeDec 01 2005Given an ideal $I$ and a weight vector $w$ which partially orders monomials we can consider the initial ideal $\init_w (I)$ which has the same Hilbert function. A well known construction carries this out via a one-parameter subgroup of a $\GL_{n+1}$ which ... More
J-type Carbon Stars in the Large Magellanic CloudApr 16 2003A sample of 1497 carbon stars in the Large Magellanic Cloud has been observed in the red part of the spectrum with the 2dF facility on the AAT. Of these, 156 have been identified as J-type (i.e. 13C-rich) carbon stars using a technique which provides ... More
Nearly Coherent Oscillations in Type I X-Ray Bursts from KS 1731-260Mar 16 2000Oct 04 2000We present an analysis of the nine type I X-ray bursts that were observed from KS 1731-260 with RXTE. We find that the bursts divide naturally into two populations: ``fast bursts'' occur on the Banana Branch when the accretion rate is high and exhibit ... More
Peak Luminosities of Bursts from GRO J1744-28 measured with the RXTE PCADec 29 1997GRO J1744-28, discovered by BATSE in December 95, is the second neutron star system known to produce frequent accretion powered bursts. The system has been regularly monitored with the RXTE PCA since the peak of the first outburst in January 96 at which ... More
Physical properties of V$_{1-x}$Ti$_{x}$O$_{2}$ (0 $<$ x $<$ 0.187) single crystalsDec 17 2014Feb 04 2015Free standing, low strain, single crystals of pure and titanium doped VO$_{2}$ were grown out of an excess of V$_{2}$O$_{5}$ using high temperature solution growth techniques. At $T_{MI} \sim$ 340 K, pure VO$_{2}$ exhibits a clear first-order phase transition ... More
Constraining Quasar Relativistic Reflection Regions and Spins with MicrolensingJan 17 2019May 01 2019We present an analysis of Chandra spectra of five gravitationally lensed active galactic nuclei. We confirm the previous detections of FeK$\alpha$ emission lines in most images of these objects with high significance. The line energies range from 5.8 ... More
Mitchell-style forcing, with small working parts and collections of models as side conditions, and gap-one simplified morassesNov 22 2014We give a modification of Mitchell's technique for adding objects of size $\omega_2$ with conditions with finite working parts in which the collections of models used as side conditions are very highly structured, arguably making them more wieldy. We ... More
A Result of Metastability for an Infinite System of Spiking NeuronsMay 16 2019In 2018, Ferrari et al. wrote a paper called "Phase Transition for Infinite Systems of Spiking Neurons" in which they introduced a continuous time stochastic model of interacting neurons. This model has a parameter $\gamma$, corresponding to the rate ... More
Toposes of Discrete Monoid ActionsMay 24 2019Properties of toposes of right $M$-sets are studied, and these toposes are characterised up to equivalence by their canonical points. The solution to the corresponding Morita equivalence problem is presented in the form of an equivalence between a 2-category ... More
Lithium in LMC carbon starsApr 16 2003Nineteen carbon stars that show lithium enrichment in their atmospheres have been discovered among a sample of 674 carbon stars in the Large Magellanic Cloud. Six of the Li-rich carbon stars are of J-type, i.e. with strong 13C isotopic features. No super-Li-rich ... More
Low energy defibrillation in human cardiac tissue: a simulation studyMay 02 2008Nov 25 2008We aim to assess the effectiveness of feedback controlled resonant drift pacing as a method for low energy defibrillation. Antitachycardia pacing is the only low energy defibrillation approach to have gained clinical significance, but it is still suboptimal. ... More
The Most Massive Black Holes in the Universe: Effects of Mergers in Massive Galaxy ClustersFeb 07 2007Jun 19 2007Recent observations support the idea that nuclear black holes grew by gas accretion while shining as luminous quasars at high redshift, and they establish a relation of the black hole mass with the host galaxy's spheroidal stellar system. We develop an ... More
An atlas of coronal electron density at 5Rs I: Data processing and calibrationSep 10 2015Tomography of the solar corona can provide cruicial constraints for models of the low corona, unique information on changes in coronal structure and rotation rates, and a valuable boundary condition for models of the heliospheric solar wind. This is the ... More
The information-carrying capacity of certain quantum channelsJul 16 2010In this thesis we analyse the type of states and ensembles which achieve the capacity for certain quantum channels carrying classical information. We first concentrate on the product-state capacity of a particular quantum channel, that is, the capacity ... More
Convergence properties of Donaldson's $T$-iterations on the Riemann sphereJun 28 2007Aug 25 2008In a recent paper Donaldson defines three operators on a space of Hermitian metrics on a complex projective manifold: $T, T_{\nu}, T_K.$ Iterations of these operators converge to balanced metrics, and these themselves approximate constant scalar curvature ... More
In polytopes, small balls about some vertex minimize perimeterApr 20 2004Dec 23 2006In (the surface of) a convex polytope P^n in R^n+1, for small prescribed volume, geodesic balls about some vertex minimize perimeter. This revision corrects a mistake in the mass bound argument in the proof of Theorem 3.8.
Mean action of periodic orbits of area-preserving annulus diffeomorphismsOct 11 2018Nov 08 2018An area-preserving diffeomorphism of an annulus has an "action function" which measures how the diffeomorphism distorts curves. The average value of the action function over the annulus is known as the Calabi invariant of the diffeomorphism, while the ... More
Quadratic twists of abelian varieties and disparity in Selmer ranksJun 19 2017We study the parity of 2-Selmer ranks in the family of quadratic twists of a fixed principally polarised abelian variety over a number field. Specifically, we determine the proportion of twists having odd (resp. even) 2-Selmer rank. This generalises work ... More
The Levy-Gromov Isoperimetric Inequality in Convex Manifolds with BoundaryOct 10 2007We observe after Bayle and Rosales that the Levy-Gromov isoperimetric inequality generalizes to convex manifolds with boundary.
An atlas of coronal electron density at 5Rs II: A spherical harmonic method for density reconstructionAug 21 2019This is the second of a series of three papers that present a methodology with the aim of creating a set of maps of the coronal density over a period of many years. This paper describes a method for reconstructing the coronal electron density based on ... More
Near-resonant optical forces beyond the two-level approximation for a continuous source of spin-polarized cold atomsJan 18 2013Mar 14 2013We propose a method to generate a source of spin-polarized cold atoms which are continuously extracted and guided from a magneto-optical trap using an atom-diode effect. We show that it is possible to create a pipe-like potential by overlapping two optical ... More
Issues in Light Hadron SpectroscopyNov 02 1993A high priority in light spectroscopy is to seek out and characterize various types of non-$(Q\bar{Q}$) meson. The large quantity of new data now appearing will present a great opportunity. To identify the non-$(Q\bar{Q}$) intruders one needs to know ... More
Simultaneous Observations of Giant Pulses from the Crab Pulsar, with the Murchison Widefield Array and Parkes Radio Telescope: Implications for the Giant Pulse Emission MechanismJul 17 2015We report on observations of giant pulses from the Crab pulsar performed simultaneously with the Parkes radio telescope and the incoherent combination of the Murchison Widefield Array (MWA) antenna tiles. The observations were performed over a duration ... More
The low-frequency characteristics of PSR J0437-4715 observed with the Murchison Widefield ArrayJul 17 2014We report on the detection of the millisecond pulsar PSR J0437-4715 with the Murchison Widefield Array (MWA) at a frequency of 192 MHz. Our observations show rapid modulations of pulse intensity in time and frequency that arise from diffractive scintillation ... More
A strong loophole-free test of local realismNov 10 2015Sep 06 2016We present a loophole-free violation of local realism using entangled photon pairs. We ensure that all relevant events in our Bell test are spacelike separated by placing the parties far enough apart and by using fast random number generators and high-speed ... More
Low Frequency Imaging of Fields at High Galactic Latitude with the Murchison Widefield Array 32-Element PrototypeMar 26 2012The Murchison Widefield Array (MWA) is a new low-frequency, wide field-of-view radio interferometer under development at the Murchison Radio-astronomy Observatory (MRO) in Western Australia. We have used a 32-element MWA prototype interferometer (MWA-32T) ... More
Classical dispersion-cancellation interferometryApr 30 2007Even-order dispersion cancellation, an effect previously identified with frequency-entangled photons, is demonstrated experimentally for the first time with a linear, classical interferometer. A combination of a broad bandwidth laser and a high resolution ... More
Measurements of Compton Scattered Transition Radiation at High Lorentz FactorsSep 17 2002Feb 05 2004X-ray transition radiation can be used to measure the Lorentz factor of relativistic particles. Standard transition radiation detectors (TRDs) typically incorporate thin plastic foil radiators and gas-filled x-ray detectors, and are sensitive up to \gamma ... More
Observations of the Pulsar Wind Nebula HESS J1825-137 with H.E.S.S. IIAug 10 2017We present a new and deep analysis of the pulsar wind nebula (PWN) HESS\,J1825--137 with a comprehensive data set of almost 400 hours taken with the H.E.S.S. array between 2004 and 2016. The large amount of data, and the inclusion of low-threshold H.E.S.S. ... More
Fast beam steering with full polarization control using a galvanometric optical scanner and polarization controllerMay 22 2012Optical beam steering is a key element in many industrial and scientific applications like in material processing, information technologies, medical imaging and laser display. Even though galvanometer-based scanners offer flexibility, speed and accuracy ... More
Fluctuations in viscous fingeringJun 27 2001Oct 16 2001Our experiments on viscous (Saffman-Taylor) fingering in Hele-Shaw channels reveal finger width fluctuations that were not observed in previous experiments, which had lower aspect ratios and higher capillary numbers Ca. These fluctuations intermittently ... More
Tests of constituent-quark generation methods which maintain both the nucleon center of mass and the desired radial distribution in Monte Carlo Glauber modelsMar 29 2016Jul 07 2016Several methods of generating three constituent-quarks in a nucleon are evaluated which explicitly maintain the nucleon's center of mass and desired radial distribution and can be used within Monte Carlo Glauber frameworks. The geometric models provided ... More
Observation of Kosterlitz-Thouless spin correlations in the colossally magnetoresistive layered manganite $La_{1.2}Sr_{1.8}Mn_{2}O_{7}$Sep 03 1999The spin correlations of the bilayer manganite $La_{1.2}Sr_{1.8}Mn_{2}O_{7}$ have been studied using neutron scattering. On cooling within the paramagnetic state, we observe purely two-dimensional behavior with a crossover to three-dimensional scaling ... More
Quantum-coherent dynamics in photosynthetic charge separation revealed by wavelet analysisMay 21 2017Experimental/theoretical evidence for sustained vibration-assisted electronic (vibronic) coherence in the Photosystem II Reaction Center (PSII RC) indicates that photosynthetic solar-energy conversion might be optimized through the interplay of electronic ... More
Chandra Detects a Rapid Flare in the Gravitationally Lensed Mini-BALQSO RX J0911.4+0551Apr 27 2001The mini Broad Absorption Line (BAL) quasar RX J0911.4+0551 was observed with the Advanced CCD Imaging Spectrometer (ACIS) of the Chandra X-ray Observatory for ~ 29 ks as part of a gravitational lens (GL) survey aimed at measuring time-delays. Timing ... More
Ultra-fast quantum randomness generation by accelerated phase diffusion in a pulsed laser diodeJan 22 2014We demonstrate a high bit-rate quantum random number generator by interferometric detection of phase diffusion in a gain-switched DFB laser diode. Gain switching at few-GHz frequencies produces a train of bright pulses with nearly equal amplitudes and ... More
Real-time vector field tracking with a cold-atom magnetometerMar 10 2013Apr 30 2013We demonstrate a fast three-axis optical magnetometer using cold, optically-trapped $^{87}$Rb gas as a sensor. By near-resonant Faraday rotation we record the free-induction decay following optical pumping along two orthogonal axes to obtain the three ... More
Polarization change induced by a galvanometric optical scannerMar 23 2010Jul 20 2010We study the optical properties of a two-axis galvanometric optical scanner constituted by a pair of rotating planar mirrors, focusing our attention on the transformation induced on the polarization state of the input beam. We obtain the matrix that defines ... More
Long-term laser frequency stabilization using fiber interferometersOct 13 2014Jul 03 2015We report long-term laser frequency stabilization using only the target laser and a pair of 5 m fiber interferometers, one as a frequency reference and the second as a sensitive thermometer to stabilize the frequency reference. When used to stabilize ... More
Precision measurement of spin-dependent inter-hyperfine scattering lengths in $^{87}$RbApr 16 2019May 27 2019We present precision measurements of the $f=1$ to $f=2$ inter-hyperfine scattering lengths in a single-domain $^{87}$Rb spinor Bose-Einstein condensate. The inter-hyperfine interaction leads to a strong and state-dependent modification of the spin-mixing ... More
Certified quantum non-demolition measurement of material systemsMar 29 2012An extensive debate on quantum non-demolition (QND) measurement, reviewed in Grangier et al. [Nature, {\bf 396}, 537 (1998)], finds that true QND measurements must have both non-classical state-preparation capability and non-classical information-damage ... More
Quantum enhanced measurements without entanglementJan 18 2017Apr 16 2018Quantum-enhanced measurements exploit quantum mechanical effects for increasing the sensitivity of measurements of certain physical parameters and have great potential for both fundamental science and concrete applications. Most of the research has so ... More
A Capillary Surface with No Radial LimitsFeb 06 2017In 1996, Kirk Lancaster and David Siegel investigated the existence and behavior of radial limits at a corner of the boundary of the domain of solutions of capillary and other prescribed mean curvature problems with contact angle boundary data. In Theorem ... More
Dynamics of the Krichever construction in several variablesJan 09 2002Jun 11 2003The Krichever construction in one variable, that is, for spectral curves, linearizes the KdV-hierarchy on the jacobian of the curve. We carry out an appropriate generalization of the Krichever construction for an arbitrary projective variety $X$ and determine ... More
Entanglement-enhanced probing of a delicate material systemDec 19 2012Quantum metrology uses entanglement and other quantum effects to improve the sensitivity of demanding measurements. Probing of delicate systems demands high sensitivity from limited probe energy and has motivated the field's key benchmark-the standard ... More
Narrowband tunable filter based on velocity-selective optical pumping in an atomic vaporDec 12 2008Mar 23 2009We demonstrate a tunable, narrow-band filter based on optical-pumping-induced circular dichroism in rubidium vapor. The filter achieves a peak transmission of 14.6%, a linewidth of 80 MHz, and an out-of-band extinction >35 dB. The transmission peak can ... More
Entanglement and extreme planar spin squeezingMay 25 2017Nov 29 2017We introduce an entanglement-depth criterion optimized for planar quantum squeezed (PQS) states. It is connected with the sensitivity of such states for estimating an arbitrary, not necessarily small phase. We compare numerically our criterion with the ... More
Simultaneous tracking of spin angle and amplitude beyond classical limitsFeb 28 2017We show how simultaneous, back-action evading tracking of non-commuting observables can be achieved in a widely-used sensing technology, atomic interferometry. Using high-dynamic-range dynamically-decoupled quantum non-demolition (QND) measurements on ... More
Atom-Resonant Heralded Single Photons by Interaction-Free MeasurementFeb 02 2011We demonstrate the generation of rubidium-resonant heralded single photons for quantum memories. Photon pairs are created by cavity-enhanced down-conversion and narrowed in bandwidth to 7 MHz with a novel atom-based filter operating by "interaction-free ... More
Quantum atom-light interfaces in the gaussian description for spin-1 systemsMay 02 2013We extend the covariance-matrix description of atom--light quantum interfaces, originally developed for real and effective spin-1/2 atoms, to include "spin alignment" degrees of freedom. This allows accurate modeling of optically-probed spin-1 ensembles ... More
Generation of fresh and pure random numbers for loophole-free Bell testsJun 08 2015Dec 17 2015We demonstrate extraction of randomness from spontaneous-emission events less than 36 ns in the past, giving output bits with excess predictability below $10^{-5}$ and strong metrological randomness assurances. This randomness generation strategy satisfies ... More