Results for "Beth Biller"

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The First Direct Distance and Luminosity Determination for a Self-Luminous Giant Exoplanet: The Trigonometric Parallax to 2MASS1207334-393254AbAug 30 2007Sep 28 2007We present the first trigonometric parallax and distance for a young planetary mass object. A likely TW Hya cluster member, 2MASSW J1207334-393254Ab (hereafter 2M1207Ab) is an M8 brown dwarf with a mid to late L type planetary mass companion. Recent observations ... More
Directly observing continuum emission from self-gravitating spiral wavesFeb 03 2016We use a simple, self-consistent, self-gravitating semi-analytic disc model to conduct an examination of the parameter space in which self-gravitating discs may exist. We then use Monte-Carlo radiative transfer to generate synthetic ALMA images of these ... More
Constraints on Extrasolar Planet Populations from VLT NACO/SDI and MMT SDI and Direct Adaptive Optics Imaging Surveys: Giant Planets are Rare at Large SeparationsJun 28 2007Oct 10 2007We examine the implications for the distribution of extrasolar planets based on the null results from two of the largest direct imaging surveys published to date. Combining the measured contrast curves from 22 of the stars observed with the VLT NACO adaptive ... More
Suppressing Speckle Noise for Simultaneous Differential Extrasolar Planet Imaging (SDI) at the VLT and MMTJan 03 2006We discuss the instrumental and data reduction techniques used to suppress speckle noise with the Simultaneous Differential Imager (SDI) implemented at the VLT and the MMT. SDI uses a double Wollaston prism and a quad filter to take 4 identical images ... More
Resolving the Dusty Circumstellar Structure of the Enigmatic Symbiotic Star CH Cygni with the MMT Adaptive Optics SystemApr 14 2006We imaged the symbiotic star CH Cyg and two PSF calibration stars using the unique 6.5m MMT deformable secondary adaptive optics system. Our high-resolution (FWHM=0.3"), very high Strehl (98%+-2%) mid-infrared (9.8 and 11.7 um) images of CH Cyg allow ... More
The Hawaii Infrared Parallax Program. III. 2MASS J0249-0557 c: A Wide Planetary-mass Companion to a Low-mass Binary in the beta Pic Moving GroupJul 13 2018Jul 17 2018We have discovered a wide planetary-mass companion to the $\beta$ Pic moving group member 2MASSJ02495639-0557352 (M6 VL-G) using CFHT/WIRCam astrometry from the Hawaii Infrared Parallax Program. In addition, Keck laser guide star adaptive optics aperture-masking ... More
Astrometric Calibration of the Gemini NICI Planet-Finding CampaignNov 03 2014We describe the astrometric calibration of the Gemini NICI Planet-Finding Campaign. The Campaign requires a relative astrometric accuracy of $\approx$ 20 mas across multi-year timescales in order to distinguish true companions from background stars by ... More
The Gemini NICI Planet-Finding Campaign: Asymmetries in the HD 141569 discApr 20 2015May 05 2015We report here the highest resolution near-IR imaging to date of the HD 141569A disc taken as part of the NICI Science Campaign. We recover 4 main features in the NICI images of the HD 141569 disc discovered in previous HST imaging: 1) an inner ring / ... More
Variability of the Lowest Mass Objects in the AB Doradus Moving GroupOct 19 2017Oct 20 2017We present the detection of [$3.6~\mu$m] photometric variability in two young, L/T transition brown dwarfs, WISE J004701.06+680352.1 (W0047) and 2MASS J2244316+204343 (2M2244) using the \textit{Spitzer Space Telescope}. We find a period of $16.4\pm0.2~$hr ... More
SNO+ with TelluriumMay 14 2014The SNO+ experiment, currently undergoing commissioning, will be a large scale liquid scintillator detector capable of studying a variety of physics topics, with the highest priority being a sensitive search for neutrinoless double beta decay. The collaboration ... More
NACO-SDI direct imaging search for the exoplanet Eps Eri bMar 13 2007The active K2V star $\epsilon$ Eri hosts the most nearby known extrasolar planet. With an angular separation of about 1" on average, and an age of a few to several hundred Myrs, $\epsilon$ Eri b is one of the prime candidates for becoming the first definitive ... More
Detection of Nine M8.0-L0.5 Binaries: The Very Low Mass Binary Population and its Implications for Brown Dwarf and VLM Star FormationJan 06 2003Use of the highly sensitive Hokupa'a/Gemini curvature wavefront sensor has allowed direct adaptive optics (AO) guiding on very low mass (VLM) stars with SpT=M8.0-L0.5. A survey of 39 such objects detected 9 VLM binaries. Most of these systems are tight ... More
A Keck LGS AO Search for Brown Dwarf and Planetary Mass Companions to Upper Scorpius Brown DwarfsJan 25 2011Jan 27 2011We searched for binary companions to 20 young brown dwarfs in the Upper Scorpius association (145 pc, 5 Myr, nearest OB association) with the the Laser Guide Star adaptive optics system and the facility infrared camera NIRC2 on the 10 m Keck II telescope. ... More
Constraining the multiplicity statistics of the coolest brown dwarfs: binary fraction continues to decrease with spectral typeJun 22 2018Jul 07 2018Binary statistics of the latest-type T and Y brown dwarfs are sparse and it is unclear whether the trends seen in the multiplicity properties of their more massive counterparts hold for the very coolest brown dwarfs. We present results from a search for ... More
Disc fragmentation rarely forms planetary-mass objectsAug 26 2015It is now reasonably clear that disc fragmentation can only operate in the outer parts of protostellar discs ($r > 50$ au). It is also expected that any object that forms via disc fragmentation will have an initial mass greater than that of Jupiter. However, ... More
An Imaging Survey for Extrasolar Planets around 45 Close, Young Stars with SDI at the VLT and MMTMay 01 2007We present the results of a survey of 45 young (<250 Myr), close (<50 pc) stars with the Simultaneous Differential Imager (SDI) implemented at the VLT and the MMT for the direct detection of extrasolar planets. As part of the survey, we observed 54 objects ... More
Pushing the Limits of Exoplanet Discovery via Direct Imaging with Deep LearningApr 12 2019Further advances in exoplanet detection and characterisation require sampling a diverse population of extrasolar planets. One technique to detect these distant worlds is through the direct detection of their thermal emission. The so-called direct imaging ... More
In Pursuit of the Least Luminous GalaxiesJul 28 2009The dwarf galaxy companions to the Milky Way are unique cosmological laboratories. With luminosities as low as 10^-7 L_MW, they inhabit the lowest mass dark matter halos known to host stars and are presently the most direct tracers of the distribution, ... More
Two New Milky Way CompanionsJun 20 2005We discuss the detection limits and current status of a uniform survey of SDSS I for ultra-faint Milky Way dwarf galaxies. We present the properties of two new, low surface brightness Milky Way companions discovered as a result of this survey. One of ... More
Probing Majorana neutrinos in the regime of the normal mass hierarchyJun 24 2013May 14 2014An approach to developing a feasible neutrinoless double beta decay experiment capable of probing Majorana masses in the regime of the nondegenerate normal neutrino mass hierarchy is proposed. For such an experiment, this study suggests that 130Te is ... More
The very nearby M/T dwarf binary SCR 1845-6357Jun 26 2007The recently discovered star SCR 1845-6357 is the first late M/T dwarf binary discovered. SCR 1845 is a particular object due to its tight orbit (currently around 4 AU) and its proximity to the Sun (3.85 pc). We present spatially resolved VLT/NACO images ... More
Magellan Adaptive Optics first-light observations of the exoplanet $β$ Pic b. I. Direct imaging in the far-red optical with MagAO+VisAO and in the near-IR with NICIMar 03 2014We present the first ground-based CCD ($\lambda < 1\mu$m) image of an extrasolar planet. Using MagAO's VisAO camera we detected the extrasolar giant planet (EGP) $\beta$ Pictoris b in $Y$-short ($Y_S$, 0.985 $\mu$m), at a separation of $0.470 \pm 0.010''$ ... More
Atmospheric Habitable Zones in Y Dwarf AtmospheresNov 28 2016We use a simple organism lifecycle model to explore the viability of an atmospheric habitable zone (AHZ), with temperatures that could support Earth-centric life, which sits above an environment that does not support life. We illustrate this idea using ... More
Evidence Against an Edge-On Disk Around the Extrasolar Planet 2MASS 1207 b and a New Thick Cloud Explanation for its Under-LuminosityMar 09 2011(Abridged) Since the discovery of the first directly-imaged, planetary-mass object, 2MASS 1207 b, several works have sought to explain a disparity between its observed temperature and luminosity. Given its known age, distance, and spectral type, 2MASS ... More
The Gemini NICI Planet-Finding Campaign: The Frequency of Planets around Young Moving Group StarsSep 05 2013We report results of a direct imaging survey for giant planets around 80 members of the Beta Pic, TW Hya, Tucana-Horologium, AB Dor, and Hercules-Lyra moving groups, observed as part of the Gemini NICI Planet-Finding Campaign. For this sample, we obtained ... More
A Search for Variability in Exoplanet Analogues and Low-Gravity Brown DwarfsNov 20 2018We report the results of a $J$-band survey for photometric variability in a sample of young, low-gravity objects using the New Technology Telescope (NTT) and the United Kingdom InfraRed Telescope (UKIRT). Surface gravity is a key parameter in the atmospheric ... More
Multi-site Event Discrimination in Large Liquid Scintillation DetectorsMar 31 2019Simulation studies have been carried out to explore the ability to discriminate between single-site and multi-site energy depositions in large scale liquid scintillation detectors. A robust approach has been found that is predicted to lead to a significant ... More
Measurement of the Multi-TeV gamma-ray Flare-Spectra of Markarian 421 and Markarian 501Aug 28 1998The energy spectrum of Markarian~421 in flaring states has been measured from 0.3 to 10 TeV using both small zenith angle and large zenith angle observations with the Whipple Observatory 10 m imaging telescope. The large zenith angle technique is useful ... More
Comment on "Stronger subadditivity of entropy" by Lieb and Seiringer math-ph/0412009Mar 08 2006Apr 04 2006We show how recent results of Lieb and Seiringer [math-ph/0412009; Phys. Rev. A 71, 062329 (2005)] can be obtained from repeated use of the monotonicity of relative entropy under partial traces, and explain how to use their approach to obtain tighter ... More
Quantum noise influencing human behaviour could fake effectiveness of drugs in clinical trialsAug 01 2002To test the effectiveness of a drug one can advice two randomly selected groups of patients to take or not to take it, respectively. It is well-known that the causal effect cannot be identified if not all patients comply. This holds even when the non-compliers ... More
Polynomial-Time Solution to the Hidden Subgroup Problem for a Class of non-abelian GroupsDec 24 1998We present a family of non-abelian groups for which the hidden subgroup problem can be solved efficiently on a quantum computer.
Quantum algorithm for finding periodicities in the spectrum of a black-box Hamiltonian or unitary transformationAug 10 2001Estimating the eigenvalues of a unitary transformation U by standard phase estimation requires the implementation of controlled-U-gates which are not available if U is only given as a black box. We show that a simple trick allows to measure eigenvalues ... More
Bounds on the entropy generated when timing information is extracted from microscopic systemsJan 23 2003We consider Hamiltonian quantum systems with energy bandwidth \Delta E and show that each measurement that determines the time up to an error \Delta t generates at least the entropy (\hbar/(\Delta t \Delta E))^2/2. Our result describes quantitatively ... More
Are there quantum bounds on the recyclability of clock signals in low power computers?Feb 11 2002Even if a logical network consists of thermodynamically reversible gate operations, the computation process may have high dissipation rate if the gate implementation is controlled by external clock signals. It is an open question whether the global clocking ... More
Cyclic Quantum Error-Correcting Codes and Quantum Shift RegistersOct 14 1999We transfer the concept of linear feed-back shift registers to quantum circuits. It is shown how to use these quantum linear shift registers for encoding and decoding cyclic quantum error-correcting codes.
On the Complexity of Quantum Searching Using Complex QueriesJun 23 1997We discuss the quantum search algorithm using complex queries that has recently been published by Grover (quant-ph/9706005). We recall the algorithm adding some details showing which complex query has to be evaluated. Based on this version of the algorithm ... More
The 2-local Hamiltonian problem encompasses NPJan 17 2003We show that the NP complete problems MAX CUT and INDEPENDENT SET can be formulated as the 2-local Hamiltonian problem as defined by Kitaev. He introduced the quantum complexity class BQNP as the quantum analog of NP, and showed that the 5-local Hamiltonian ... More
A Note on Non-Additive Quantum CodesMar 10 1997A method to combine two quantum error-correcting codes is presented. Even when starting with additive codes, the resulting code might be non-additive. Furthermore, the notion of the erasure space is introduced which gives a full characterisation of the ... More
Fast Data Management with Distributed Streaming SQLNov 12 2015To stay competitive in today's data driven economy, enterprises large and small are turning to stream processing platforms to process high volume, high velocity, and diverse streams of data (fast data) as they arrive. Low-level programming models provided ... More
"Galaxy," DefinedMar 12 2012Jun 29 2012A growing number of low luminosity and low surface brightness astronomical objects challenge traditional notions of both galaxies and star clusters. To address this, we propose a definition of galaxy independent of the cold dark matter model of the universe: ... More
New Construction of Mutually Unbiased Bases in Square DimensionsJul 12 2004We show that k=w+2 mutually unbiased bases can be constructed in any square dimension d=s^2 provided that there are w mutually orthogonal Latin squares of order s. The construction combines the design-theoretic objects (k,s)-nets (which can be constructed ... More
Fragility of a class of highly entangled states of many quantum-bitsJul 10 1999We consider a Quantum Computer with n quantum-bits (`qubits'), where each qubit is coupled independently to an environment affecting the state in a dephasing or depolarizing way. For mixed states we suggest a quantification for the property of showing ... More
Distinguishing n Hamiltonians on C^n by a single measurementMar 06 2001If an experimentalist wants to decide which one of n possible Hamiltonians acting on an n dimensional Hilbert space is present, he can conjugate the time evolution by an appropriate sequence of known unitary transformations in such a way that the different ... More
Remark on multi-particle observables and entangled states with constant complexityMar 24 2000We show that every density matrix of an n-particle system prepared by a quantum network of constant depth is asymptotically commuting with the mean-field observables. We introduce certain pairs of hypersurfaces in the space of density matrices and give ... More
Hamiltonian Effective PotentialDec 03 1992A Hamiltonian effective potential (the logarithm of the square of the wave functional) is defined and calculated at the tree and one loop levels in a $\phi^4$ scalar field theory. The loop expansion for eigenfunctionals is equivalent to the combination ... More
An asymptotic parallel-in-time method for highly oscillatory PDEsMar 26 2013Feb 20 2014We present a new time-stepping algorithm for nonlinear PDEs that exhibit scale separation in time. Our scheme combines asymptotic techniques (which are inexpensive but can have insufficient accuracy) with parallel-in-time methods (which, alone, can be ... More
Partially Specified Spatial Autoregressive Model with Artificial Neural NetworkJan 24 2018Spatial autoregressive model, introduced by Clif and Ord in 1970s has been widely applied in many areas of science and econometrics such as regional economics, public finance, political sciences, agricultural economics, environmental studies and transportation ... More
Reliable Access to Massive Restricted Texts: Experience-based EvaluationMar 02 2019Libraries are seeing growing numbers of digitized textual corpora that frequently come with restrictions on their content. Computational analysis corpora that are large, while of interest to scholars, can be cumbersome because of the combination of size, ... More
Planets Around Low-Mass Stars (PALMS). V. Age-Dating Low-Mass Companions to Members and Interlopers of Young Moving GroupsMay 06 2015We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7-M4.5), most of which have recently been identified as candidate members of nearby young moving groups (YMGs; 8-120 ... More
The Gemini NICI Planet-Finding Campaign: Discovery of a Multiple System Orbiting the Young A Star HD 1160Feb 13 2012Mar 03 2012We report the discovery by the Gemini NICI Planet-Finding Campaign of two low-mass companions to the young A0V star HD 1160 at projected separations of 81 +/- 5 AU (HD 1160 B) and 533 +/- 25 AU (HD 1160 C). VLT images of the system taken over a decade ... More
Stellar companions to exoplanet host stars: Lucky Imaging of transiting planet hostsSep 18 2012Observed properties of stars and planets in binary/multiple star systems provide clues to planet formation and evolution. We extended our survey for visual stellar companions to the hosts of transiting exoplanets by 21 stars, using the Lucky Imaging technique ... More
The Gemini NICI Planet-Finding Campaign: Discovery of a Close Substellar Companion to the Young Debris Disk Star PZ TelJul 27 2010We report the discovery of a tight substellar companion to the young solar analog PZ Tel, a member of the Beta Pictoris moving group observed with high contrast adaptive optics imaging as part of the Gemini NICI Planet-Finding Campaign. The companion ... More
A Complexity Measure for Continuous Time Quantum AlgorithmsSep 22 2000We consider unitary dynamical evolutions on n qubits caused by time dependent pair-interaction Hamiltonians and show that the running time of a parallelized two-qubit gate network simulating the evolution is given by the time integral over the chromatic ... More
Synchronizing quantum clocks with classical one-way communication: Bounds on the generated entropyJun 03 2003We describe separable joint states on bipartite quantum systems that cannot be prepared by any thermodynamically reversible classical one-way communication protocol. We argue that the joint state of two synchronized microscopic clocks is always of this ... More
Quantum BCH CodesOct 14 1999After a brief introduction to both quantum computation and quantum error correction, we show how to construct quantum error-correcting codes based on classical BCH codes. With these codes, decoding can exploit additional information about the position ... More
From Curriculum Guidelines to Learning Objectives: A Survey of Five Statistics ProgramsDec 23 2014The 2000 ASA Guidelines for Undergraduate Statistics majors aimed to provide guidance to programs with undergraduate degrees in statistics as to the content and skills that statistics majors should be learning. With new guidelines forthcoming, it is important ... More
Quasi-order of clocks and synchronism and quantum bounds for copying timing informationDec 21 2001Dec 22 2001The statistical state of any (classical or quantum) system with non-trivial time evolution can be interpreted as the pointer of a clock. The quality of such a clock is given by the statistical distinguishability of its states at different times. If a ... More
Picard curves over Q with good reduction away from 3Jul 29 2014Jan 15 2016Inspired by methods of N. P. Smart, we describe an algorithm to determine all Picard curves over Q with good reduction away from 3, up to Q-isomorphism. A correspondence between the isomorphism classes of such curves and certain quintic binary forms possessing ... More
A Multi-wavelength Differential Imaging Experiment for the High Contrast Imaging TestbedJun 01 2009We discuss the results of a multi-wavelength differential imaging lab experiment with the High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Laboratory. The HCIT combines a Lyot coronagraph with a Xinetics deformable mirror in a vacuum environment ... More
Cloud Structure of the Nearest Brown Dwarfs II: High-amplitude variability for Luhman 16 A and B in and out of the 0.99 micron FeH featureSep 21 2015The re-emergence of the 0.99 $\mu$m FeH feature in brown dwarfs of early- to mid-T spectral type has been suggested as evidence for cloud disruption where flux from deep, hot regions below the Fe cloud deck can emerge. The same mechanism could account ... More
LEECH: A 100 Night Exoplanet Imaging Survey at the LBTJan 02 2014In February 2013, the LEECH (LBTI Exozodi Exoplanet Common Hunt) survey began its 100-night campaign from the Large Binocular Telescope atop Mount Graham in Arizona. LEECH nearly complements other high-contrast planet imaging efforts by observing stars ... More
A Survey of Close, Young Stars with the Simultaneous Differential Imager (SDI) at the VLT and MMTJan 03 2006We discuss the preliminary results of a survey of young (<300 Myr), close (<50 pc) stars with the Simultaneous Differential Extrasolar Planet Imager (SDI) implemented at the VLT and the MMT. SDI uses a double Wollaston prism and a quad filter to take ... More
Monotone Riemannian Metrics and Relative Entropy on Non-Commutative Probability SpacesAug 30 1998We use the relative modular operator to define a generalized relative entropy for any convex operator function g on the positive real line satisfying g(1) = 0. We show that these convex operator functions can be partitioned into convex subsets each of ... More
Causal Structures of Dynamic Black HolesApr 27 2009Dynamic space-times, especially those manifesting horizons, provide useful laboratories for examining how macroscopic quantum behaviors consistently co-generate gravitational phenomena. For this reason, the behaviors and large-scale causal structures ... More
Radial Photon Trajectories Near an Evaporating Black HoleFeb 12 2008The radial motion of photons emitted near the horizon of a black hole that evaporates at a steady rate is examined. The space-time of the black hole is generated using non-orthogonal coordinates. It is shown that some photons that are initially drawn ... More
Construction of a Penrose Diagram for a Spatially Coherent Evaporating Black HoleOct 10 2007A Penrose diagram is constructed for an example black hole that evaporates at a steady rate as measured by a distant observer, until the mass vanishes, yielding a final state Minkowski space-time. Coordinate dependencies of significant features, such ... More
On the arithmetic of simple singularities of type EJul 13 2017An ADE Dynkin diagram gives rise to a family of algebraic curves. In this paper, we use arithmetic invariant theory to study the integral points of the curves associated to the exceptional diagrams $E_6, E_7$, $E_8$. These curves are non-hyperelliptic ... More
Comments on multiplicativity of maximal p-norms when p = 2Jan 07 2004We consider the maximal p-norm associated with a completely positive map and the question of its multiplicativity under tensor products. We give a condition under which this multiplicativity holds when p = 2, and we describe some maps which satisfy our ... More
Determining Determiner Sequencing: A Syntactic Analysis for EnglishNov 03 1994Previous work on English determiners has primarily concentrated on their semantics or scoping properties rather than their complex ordering behavior. The little work that has been done on determiner ordering generally splits determiners into three subcategories. ... More
A One-Dimensional Model for Many-Electron Atoms in Extremely Strong Magnetic Fields: Maximum Negative IonizationFeb 21 1999We consider a one-dimensional model for many-electron atoms in strong magnetic fields in which the Coulomb potential and interactions are replaced by one-dimensional regularizations associated with the lowest Landau level. For this model we show that ... More
Contraction coefficients for noisy quantum channelsAug 14 2015Generalized relative entropy, monotone Riemannian metrics, geodesic distance, and trace distance are all known to decrease under the action of quantum channels. We give some new bounds on, and relationships between, the maximal contraction for these quantities. ... More
A pair of optimal inequalities related to the error functionNov 11 1997The Error Function \begin{eqnarray} V(x) & \equiv & \sqrt{\pi} e^{x^2} [1 - \hbox{erf}(x)] \\ & = & \int_0^\infty \frac{ e^{-u} }{\sqrt{x^2 + u}} du = 2 e^{x^2}\int_x^\infty e^{-t^2} dt \nonumber \end{eqnarray} arises in many contexts, from probability ... More
One-dimensional models for atoms in strong magnetic fields, II: Anti-Symmetry in the Landau LevelsAug 28 2003Nov 14 2003Electrons in strong magnetic fields can be described by one-dimensional models in which the Coulomb potential and interactions are replaced by regularizations associated with the lowest Landau band. For a large class of models of these type, we show that ... More
Study of a Class of Regularizations of 1/|x| using Gaussian IntegralsFeb 21 1999Jan 18 2000This paper presents a comprehensive study of a class of functions which approximate 1/|x| for large x but which are finite at the origin. These functions arise naturally in the study of atoms in strong magnetic fields where the so-called "Landau states" ... More
A Unified Treatment of Convexity of Relative Entropy and Related Trace Functions, with Conditions for EqualityMar 17 2009Jul 29 2010We introduce a generalization of relative entropy derived from the Wigner-Yanase-Dyson entropy and give a simple, self-contained proof that it is convex. Moreover, special cases yield the joint convexity of relative entropy, and for the map (A,B) --> ... More
A spatial capture-recapture model for territorial speciesMay 08 2014Advances in field techniques have lead to an increase in spatially-referenced capture-recapture data to estimate a species' population size as well as other demographic parameters and patterns of space usage. Statistical models for these data have assumed ... More
Deep $z$-band observations of the coolest Y dwarfOct 21 2014WISE J085510.83-071442.5 (hereafter, WISE 0855-07) is the coolest Y dwarf known to date and is located at a distance of 2.31$\pm 0.08$ pc, giving it the fourth largest parallax of any known star or brown dwarf system. We report deep $z$-band observations ... More
Observing Strategies for the NICI Campaign to Directly Image Extrasolar PlanetsSep 17 2008We discuss observing strategy for the Near Infrared Coronagraphic Imager (NICI) on the 8-m Gemini South telescope. NICI combines a number of techniques to attenuate starlight and suppress superspeckles: 1) coronagraphic imaging, 2) dual channel imaging ... More
High-Cadence, High-Contrast Imaging for Exoplanet Mapping: Observations of the HR 8799 Planets with VLT/SPHERE Satellite Spot-Corrected Relative PhotometryFeb 09 2016Feb 10 2016Time-resolved photometry is an important new probe of the physics of condensate clouds in extrasolar planets and brown dwarfs. Extreme adaptive optics systems can directly image planets, but precise brightness measurements are challenging. We present ... More
Mid-Infrared Imaging of the Post-AGB Star AC Herculis with the MMT Adaptive Optics SystemOct 20 2003We utilized the MMT's unique deformable secondary adaptive optics system to produce high-resolution (FWHM=0.3"), very high Strehl mid-infrared (9.8, 11.7 & 18 micron) images of the post-AGB star AC Her. The very high (98+/-2%) Strehls achieved with Mid-IR ... More
Performance of the Near-infrared coronagraphic imager on Gemini-SouthSep 17 2008We present the coronagraphic and adaptive optics performance of the Gemini-South Near-Infrared Coronagraphic Imager (NICI). NICI includes a dual-channel imager for simultaneous spectral difference imaging, a dedicated 85-element curvature adaptive optics ... More
Astro2020 White Paper: The L/T TransitionMar 15 2019The L/T transition is an important evolutionary phase in brown dwarf atmospheres, providing us with a unique opportunity to explore the effects of clouds, convection, winds, gravity and metallicity across a very narrow temperature range. Understanding ... More
The Gemini NICI Planet-Finding Campaign: The Companion Detection PipelineOct 15 2013Oct 21 2013We present the high-contrast image processing techniques used by the Gemini NICI Planet-Finding Campaign to detect faint companions to bright stars. NICI (Near Infrared Coronagraphic Imager) is an adaptive optics instrument installed on the 8-m Gemini ... More
The Gemini NICI Planet-Finding Campaign: The Offset Ring of HR 4796 AApr 25 2014We present J, H, CH_4 short (1.578 micron), CH_4 long (1.652 micron) and K_s-band images of the dust ring around the 10 Myr old star HR 4796 A obtained using the Near Infrared Coronagraphic Imager (NICI) on the Gemini-South 8.1 meter Telescope. Our images ... More
The LEECH Exoplanet Imaging Survey: Characterization of the Coldest Directly Imaged Exoplanet, GJ 504 b, and Evidence for Super-Stellar MetallicityNov 30 2015As gas giant planets and brown dwarfs radiate away the residual heat from their formation, they cool through a spectral type transition from L to T, which encompasses the dissipation of cloud opacity and the appearance of strong methane absorption. While ... More
High contrast imaging at the LBT: the LEECH exoplanet imaging surveyJul 10 2014In Spring 2013, the LEECH (LBTI Exozodi Exoplanet Common Hunt) survey began its $\sim$130-night campaign from the Large Binocular Telescope (LBT) atop Mt Graham, Arizona. This survey benefits from the many technological achievements of the LBT, including ... More
Complexity of decoupling and time-reversal for n spins with pair-interactions: Arrow of time in quantum controlJun 15 2001Feb 15 2002Well-known Nuclear Magnetic Resonance experiments show that the time evolution according to (truncated) dipole-dipole interactions between n spins can be inverted by simple pulse sequences. Independent of n, the reversed evolution is only two times slower ... More
Quantum Reed-Solomon CodesOct 14 1999After a brief introduction to both quantum computation and quantum error correction, we show how to construct quantum error-correcting codes based on classical BCH codes. With these codes, decoding can exploit additional information about the position ... More
Fast Quantum Fourier Transforms for a Class of Non-abelian GroupsJul 22 1998An algorithm is presented allowing the construction of fast Fourier transforms for any solvable group on a classical computer. The special structure of the recursion formula being the core of this algorithm makes it a good starting point to obtain systematically ... More
Codes for the Quantum Erasure ChannelOct 28 1996Jan 17 1997The quantum erasure channel (QEC) is considered. Codes for the QEC have to correct for erasures, i. e., arbitrary errors at known positions. We show that four qubits are necessary and sufficient to encode one qubit and correct one erasure, in contrast ... More
On optimal quantum codesDec 19 2003We present families of quantum error-correcting codes which are optimal in the sense that the minimum distance is maximal. These maximum distance separable (MDS) codes are defined over q-dimensional quantum systems, where q is an arbitrary prime power. ... More
Improved Gap Estimates for Simulating Quantum Circuits by Adiabatic EvolutionMay 17 2006We use elementary variational arguments to prove, and improve on, gap estimates which arise in simulating quantum circuits by adiabatic evolution.
An Analysis of Completely-Positive Trace-Preserving Maps on 2x2 MatricesDec 31 2000Nov 03 2001We give a useful new characterization of the set of all completely positive, trace-preserving (i.e., stochastic) maps from 2x2 matrices to 2x2 matrices. These conditions allow one to easily check any trace-preserving map for complete positivity. We also ... More
A Compact Architecture for Dialogue Management Based on Scripts and Meta-OutputsJun 09 2000We describe an architecture for spoken dialogue interfaces to semi-autonomous systems that transforms speech signals through successive representations of linguistic, dialogue, and domain knowledge. Each step produces an output, and a meta-output describing ... More
Bounds on the Concavity of Quantum EntropyApr 23 2014Apr 30 2014We give new upper and lower bounds on the concavity of quantum entropy. Comparisons are given with other results in the literature.
Performing joint measurements and transformations on several qubits by operating on a single control qubitJul 23 2002An n-qubit quantum register can in principle be completely controlled by operating on a single qubit that interacts with the register via an appropriate fixed interaction. We consider a hypothetical system consisting of n spin-1/2 nuclei that interact ... More
Lower Bound on the Chromatic Number by Spectra of Weighted Adjacency MatricesDec 21 2001A lower bound on the chromatic number of a graph is derived by majorization of spectra of weighted adjacency matrices. These matrices are given by Hadamard products of the adjacency matrix and arbitrary Hermitian matrices.
Computing Local Invariants of Qubit SystemsDec 18 1997May 29 1998We investigate means to describe the non-local properties of quantum systems and to test if two quantum systems are locally equivalent. For this we consider quantum systems that consist of several subsystems, especially multiple qubits. We compute invariant ... More
Two QCMA-complete problemsMay 16 2003QMA and QCMA are possible quantum analogues of the complexity class NP. In QCMA the verifier is a quantum program and the proof is classical. In contrast, in QMA the proof is also a quantum state. We show that two known QMA-complete problems can be modified ... More
Bounds on the number of time steps for simulating arbitrary interaction graphsMar 14 2002Sep 26 2002In previous papers we have considered mutual simulation of n-partite pair-interaction Hamiltonians. We have focussed on the running time overhead of general simulations, while considering the required number of time steps only for special cases (decoupling ... More