Results for "Morgan W. Mitchell"

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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 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
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
Squeezed-Light Optical MagnetometryAug 10 2010Aug 25 2010We demonstrate a light-shot-noise-limited magnetometer based on the Faraday effect in a hot unpolarized ensemble of rubidium atoms. By using off-resonant, polarization-squeezed probe light, we improve the sensitivity of the magnetometer by 3.2 dB. The ... More
Atomic filtering for hybrid continuous-variable/discrete-variable quantum opticsJun 16 2014Sep 04 2014We demonstrate atomic filtering of frequency-degenerate photon pairs from a sub-threshold optical parametric oscillator (OPO). The filter, a modified Faraday anomalous dispersion optical filter (FADOF), achieves 70% peak transmission simultaneous with ... More
Ultra-Narrow Faraday Rotation Filter at the Rb D1 LineOct 11 2011Jul 14 2016We present a theoretical and experimental study of the ultra-narrow bandwidth Faraday anomalous dispersion optical filter (FADOF) operating at the rubidium D1 line (795 nm). This atomic line gives better performance than other lines for the main FADOF ... More
Sensitivity, quantum limits, and quantum enhancement of noise spectroscopiesOct 07 2016We 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
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
Phase diffusion quantum entropy source on a silicon chipApr 12 2018We report an accelerated laser phase diffusion quantum entropy source with all non-laser optical and optoelectronic elements implemented in silicon photonics. The device uses efficient and robust single-laser accelerated phase diffusion methods, and implements ... 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
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
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
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
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
Interferometric measurement of the biphoton wave functionJul 29 2014Interference between an unknown two-photon state (a "biphoton") and the two-photon component of a reference state gives a phase-sensitive arrival-time distribution containing full information about the biphoton temporal wave function. Using a coherent ... More
A quantum entropy source on an InP photonic integrated circuit for random number generationSep 12 2016Random number generators are essential to ensure performance in information technologies, including cryptography, stochastic simulations and massive data processing. The quality of random numbers ultimately determines the security and privacy that can ... More
A macroscopic quantum state analysed particle by particleOct 26 2014Explaining how microscopic entities collectively produce macroscopic phenomena is a fundamental goal of many-body physics. Theory predicts that large-scale entanglement is responsible for exotic macroscopic phenomena, but observation of entangled particles ... More
Phase-stable source of polarization-entangled photons in a linear double-pass configurationMay 07 2013We demonstrate a compact, robust, and highly efficient source of polarization-entangled photons, based on linear bi-directional down-conversion in a novel 'folded sandwich' configuration. Bi-directionally pumping a single periodically poled KTiOPO$_4$ ... More
Multi-second magnetic coherence in a single domain spinor Bose-Einstein condensateJul 30 2017We describe a compact, robust and versatile system for studying magnetic dynamics in a spinor Bose-Einstein condensate. Condensates of 87 Rb are produced by all-optical evaporation in a 1560 nm optical dipole trap, using a non-standard loading sequence ... 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
Ricci Flow and the Poincare ConjectureJul 25 2006Mar 21 2007This manuscript contains a detailed proof of the Poincare Conjecture. The arguments we present here are expanded versions of the ones given by Perelman in his three preprints posted in 2002 and 2003. This is a revised version taking in account the comments ... More
Mathematics Underlying the F-Theory/Heterotic String Duality in Eight DimensionsAug 11 2003One of the dualities in string theory, the F-theory/heterotic string duality in eight dimensions, predicts an interesting correspondence between two seemingly disparate geometrical objects. On one side of the duality there are elliptically fibered K3 ... 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
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
Non-ideal atom-light interfaces: modeling real-world effectsFeb 04 2008Feb 22 2008We present a model which describes coherent and incoherent processes in continuous-variable atom-light interfaces. We assume Gaussian states for light and atoms and formulate the system dynamics in terms of first and second moments of the angular momentum ... 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
Experimental Low-Latency Device-Independent Quantum RandomnessDec 19 2018Applications of randomness such as private key generation and public randomness beacons require small blocks of certified random bits on demand. Device-independent quantum random number generators can produce such random bits, but existing quantum-proof ... More
Quantum non-demolition measurement enables macroscopic Leggett-Garg testsMar 29 2015Oct 30 2015We show how a test of macroscopic realism based on Leggett-Garg inequalities (LGIs) can be performed in a macroscopic system. Using a continuous-variable approach, we consider quantum non-demolition (QND) measurements applied to atomic ensembles undergoing ... 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
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
Mirror Symmetry and Integral Variations of Hodge Structure Underlying One Parameter Families of Calabi-Yau ThreefoldsMay 12 2005This proceedings note introduces aspects of the authors' work relating mirror symmetry and integral variations of Hodge structure. The emphasis is on their classification of the integral variations of Hodge structure which can underly families of Calabi-Yau ... More
An Outbreak Vector-host Epidemic Model with Spatial Structure: The 2015 Zika Outbreak in Rio de JaneiroMay 27 2016Jun 22 2016Background: A deterministic model is developed for the spatial spread of an epidemic disease in a geographical setting. The disease is borne by vectors to susceptible hosts through criss-cross dynamics. The model is focused on an epidemic outbreak that ... More
The diameter of the commuting graph of a finite group with trivial centreJan 10 2013The commuting graph of a finite group with trivial centre is examined. It is shown that the connected components of the commuting graph have diameter at most 10.
Analysis of a Reaction Diffusion Model for a Reservoir Supported Spread of Infectious DiseaseJul 20 2018Motivated by recent outbreaks of the Ebola Virus, we are concerned with the role that a vector reservoir plays in supporting the spatio-temporal spread of a highly lethal disease through a host population. In our context, the reservoir is a species capable ... More
A partition theorem for a large dense linear orderJun 07 2005Let Q_K=(Q,<_Q)$ be a strongly K-dense linear order of size K for a suitable cardinal K. We prove, for all integers m > 1 that there is a finite value t_m^+ such that the set of all m-tuples from Q can be divided into t_m^+ many classes, such that whenever ... More
Dynamics of Atom-Mediated Photon-Photon Scattering I: TheoryFeb 06 2000The mediated photon-photon interaction due to the resonant Kerr nonlinearity in an inhomogeneously broadened atomic vapor is considered. The time-scale for photon-photon scattering is computed and found to be determined by the inhomogeneous broadening ... More
The Quasar Accretion Disk Size - Black Hole Mass RelationJul 02 2007We use the microlensing variability observed for nine gravitationally lensed quasars to show that the accretion disk size at 2500 Angstroms is related to the black hole mass by log(R_2500/cm) = (15.6+-0.2) + (0.54+-0.28)log(M_BH/10^9M_sun). This scaling ... More
X-Ray and Optical Microlensing in the Lensed Quasar PG 1115+080Feb 08 2008Apr 30 2008We analyzed the microlensing of the X-ray and optical emission of the lensed quasar PG 1115+080. We find that the effective radius of the X-ray emission is 1.3(+1.1 -0.5) dex smaller than that of the optical emission. Viewed as a thin disk observed at ... 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
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
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
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
Nonlinear network model analysis of vibrational energy transfer and localisation in the Fenna-Matthews-Olson complexJul 06 2016Collective protein modes are expected to be important for facilitating energy transfer in the Fenna-Matthews-Olson (FMO) complex, however to date little work has focussed on the microscopic details of these vibrations. The nonlinear network model (NNM) ... More
Dynamics of Atom-Mediated Photon-Photon Scattering II: ExperimentFeb 06 2000Temporal and angular correlations in atom-mediated photon-photon scattering are measured. Good agreement is found with the theory presented in Part~I.
Quantum control of spin-correlations in ultracold lattice gasesAug 09 2012We demonstrate that it is possible to prepare a lattice gas of ultracold atoms with a desired non-classical spin-correlation function using atom-light interaction of the kind routinely employed in quantum spin polarization spectroscopy. Our method is ... More
Measurement of Spin Projection Noise in Broadband Atomic MagnetometryNov 24 2009We measure the sensitivity of a broadband atomic magnetometer using quantum non-demolition spin measurements. A cold, dipole-trapped sample of rubidium atoms provides a long-lived spin system in a non-magnetic environment, and is probed non-destructively ... More
Real-time imaging of density ducts between the plasmasphere and ionosphereApr 24 2015Ionization of the Earth's atmosphere by sunlight forms a complex, multi-layered plasma environment within the Earth's magnetosphere, the innermost layers being the ionosphere and plasmasphere. The plasmasphere is believed to be embedded with cylindrical ... More
QND Measurement of Large-Spin Ensembles by Dynamical DecouplingMay 17 2010Quantum non-demolition (QND) measurement of collective variables by off-resonant optical probing has the ability to create entanglement and squeezing in atomic ensembles. Until now, this technique has been applied to real or effective spin one-half systems. ... More
Numerical Algorithm for Pólya Enumeration TheoremDec 13 2014Although the P\'olya enumeration theorem has been used extensively for decades, an optimized, purely numerical algorithm for calculating its coefficients is not readily available. We present such an algorithm for finding the number of unique colorings ... 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
The Panchromatic STARBurst IRregular Dwarf Survey (STARBIRDS) DataNov 15 2016Understanding star formation in resolved low mass systems requires the integration of information obtained from observations at different wavelengths. We have combined new and archival multi-wavelength observations on a set of 20 nearby starburst and ... 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
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
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
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
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
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
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
Rho-0 Meson Helicity Amplitude Ratios at HERMESJun 14 2012The study of {\rho}0 meson helicity amplitude ratios at HERMES shows that the amplitude hierarchy expected from pQCD is confirmed. The contribution of Unnatural Parity Exchange in the production of {\rho}0 mesons is significant at HERMES kinematics and ... More
Physics Updates from HERMESJan 08 2013The HERMES collaboration presents two sets of recent results: the first related to an extraction of the g2 nucleon structure function determined for DIS on a polarised target and the second related to the measurement of asymmetries related to the deeply ... 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 Sizes of the X-ray and Optical Emission Regions of RXJ1131-1231Jun 23 2009We use gravitational microlensing of the four images of the z=0.658 quasar RXJ1131-1231 to measure the sizes of the optical and X-ray emission regions of the quasar. The (face-on) scale length of the optical disk at rest frame 400 nm is 1.3 10^15cm, while ... More
Insulating transition in the flux-flow resistivity of a high temperature superconductorDec 19 2005Measurements of the DC resistivity of under-doped cuprate superconductors have revealed a metal--insulator transition at low temperatures when superconductivity is suppressed by a very large magnetic field, with the resistivity growing logarithmically ... More
Evidence for a Disk-Jet Interaction in the Microquasar GRS 1915+105Nov 01 1997We report simultaneous X-ray and infrared (IR) observations of the Galactic microquasar GRS1915+105 using XTE and the Palomar 200-inch telescope on August 13-15, 1997 UTC. During the last two nights, the microquasar GRS 1915+105 exhibited quasi-regular ... 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
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
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 Estimation of Time Delays and Quasar StructureOct 12 2007We expand our Bayesian Monte Carlo method for analyzing the light curves of gravitationally lensed quasars to simultaneously estimate time delays and quasar structure including their mutual uncertainties. We apply the method to HE1104-1805 and QJ0158-4325, ... 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
Ultrasensitive Atomic Spin Measurements with a Nonlinear InterferometerOct 22 2013May 20 2014We study nonlinear interferometry applied to a measurement of atomic spin and demonstrate a sensitivity that cannot be achieved by any linear-optical measurement with the same experimental resources. We use alignment-to-orientation conversion, a nonlinear-optical ... More
Efficient quantification of non-Gaussian spin distributionsDec 16 2011We study theoretically and experimentally the quantification of non-Gaussian distributions via non-destructive measurements. Using the theory of cumulants, their unbiased estimators, and the uncertainties of these estimators, we describe a quantification ... More
Simulations of non-Abelian gauge theories with optical latticesNov 12 2012Oct 01 2013Many phenomena occurring in strongly correlated quantum systems still await conclusive explanations. The absence of isolated free quarks in nature is an example. It is attributed to quark confinement, whose origin is not yet understood. The phase diagram ... More
Fluctuations and Pinch-Offs Observed in Viscous FingeringOct 14 2002Our experiments on viscous (Saffman-Taylor) fingering in Hele-Shaw channels reveal several phenomena that were not observed in previous experiments. At low flow rates, growing fingers undergo width fluctuations that intermittently narrow the finger as ... More
Hamiltonian Design in Atom-Light Interactions with Rubidium Ensembles: A Quantum Information ToolboxDec 03 2007Dec 05 2007We study the coupling between collective variables of atomic spin and light polarization in an ensemble of cold 87Rb probed with polarized light. The effects of multiple hyperfine levels manifest themselves as a rank-2 tensor polarizability, whose irreducible ... More
Feedback-cooling of an atomic spin ensembleMay 14 2013We describe a measurement-and-feedback technique to deterministically prepare low-entropy states of atomic spin ensembles. Using quantum non-demolition measurement and incoherent optical feedback, we drive arbitrary states in the spin-orientation space ... More
Interaction-based quantum metrology showing scaling beyond the Heisenberg limitDec 28 2010Quantum metrology studies the use of entanglement and other quantum resources to improve precision measurement. An interferometer using N independent particles to measure a parameter X can achieve at best the "standard quantum limit" (SQL) of sensitivity ... More
Real-time shot-noise-limited differential photodetection for atomic quantum controlMay 11 2016We demonstrate high-efficiency, shot-noise-limited differential photodetection with real-time signal conditioning, suitable for feedback-based quantum control of atomic systems. The detector system has quantum efficiency of 0.92, is shot-noise limited ... More
On the 14C(alpha,gamma) reaction rateOct 02 2009The 14C(alpha,gamma) reaction rate at temperatures below 0.3 GK depends on the properties of two near threshold resonances in 18O, the 1- at 6.198 MeV and the 3- at 6.404 MeV. The alpha+14C Asymptotic Normalization Coefficients (ANCs) for these resonances ... 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
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
Quantum Process Tomography on Vibrational States of Atoms in an Optical LatticeDec 29 2003Quantum process tomography is used to fully characterize the evolution of the quantum vibrational state of atoms. Rubidium atoms are trapped in a shallow optical lattice supporting only two vibrational states, which we charcterize by reconstructing the ... More
True random numbers from amplified quantum vacuumOct 04 2011Oct 17 2011Random numbers are essential for applications ranging from secure communications to numerical simulation and quantitative finance. Algorithms can rapidly produce pseudo-random outcomes, series of numbers that mimic most properties of true random numbers ... More
Magnetically Controlling the Explosion of Dirac Fermions during the Oxidation of GrapheneOct 27 2011The different physical properties of multilayered graphene or graphite relative to single layer graphene result from the Dirac spins symmetry in graphene and the Pauli spin symmetry in graphite. The Dirac symmetry in multilayers of graphene (graphite) ... More
Bright filter-free source of indistinguishable photon pairsJun 25 2008Oct 23 2008We demonstrate a high-brightness source of pairs of indistinguishable photons based on a type-II phase-matched doubly-resonant optical parametric oscillator operated far below threshold. The cavity-enhanced down-conversion output of a PPKTP crystal is ... More
Computational modeling of microstructureMay 01 2003Many materials such as martensitic or ferromagnetic crystals are observed to be in metastable states exhibiting a fine-scale, structured spatial oscillation called microstructure; and hysteresis is observed as the temperature, boundary forces, or external ... More
Sets with few differences in abelian groupsAug 22 2015Mar 29 2017Let $(G, +)$ be an abelian group. In 2004, Eliahou and Kervaire found an explicit formula for the smallest possible cardinality of the sumset $A+A$, where $A \subseteq G$ has fixed cardinality $r$. We consider instead the smallest possible cardinality ... More
Efficient and long-lived Zeeman-sublevel atomic population storage in an erbium-doped glass fiberJul 10 2015Jan 08 2016Long-lived population storage in optically pumped levels of rare-earth ions doped into solids, referred to as persistent spectral hole burning, is of significant fundamental and technological interest. However, the demonstration of deep and persistent ... More
Chandra X-ray Observations of the Quadruply Lensed Quasar RX J0911.4+0551Mar 02 2001We present results from X-ray observations of the quadruply lensed quasar RX J0911.4+0551 using data obtained with the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-ray Observatory. The 29 ks observation detects a total of ~404 X-ray ... More
A Time Delay for the Largest Gravitationally Lensed Quasar: SDSS J1004+4112Jul 21 2006We present 426 epochs of optical monitoring data spanning 1000 days from December 2003 to June 2006 for the gravitationally lensed quasar SDSS J1004+4112. The time delay between the A and B images is 38.4+/-2.0 days in the expected sense that B leads ... More