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Search Results: 1 - 10 of 334634 matches for " Jonathan S. Hodges "
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Time-keeping with electron spin states in diamond
Jonathan S. Hodges,Dirk Englund
Physics , 2011,
Abstract: Frequency standards based on atomic states, such as Rb or Cs vapors, or single trapped ions, are the most precise measures of time. Here we introduce a complementary device based on spins in a solid-state system - the nitrogen-vacancy defect in single crystal diamond. We show that this system has comparable stability to portable atomic standards and is readily incorporable as a chip-scale device. Using a pulsed spin-echo technique, we anticipate an Allan deviation of {\sigma}_y =1E-12 ({\tau})^(-1/2) with current photoluminescence detection methods and posit exceeding 1E-14 with improved diamond material processing and nanophotonic engineering.
Magnetometry of random AC magnetic fields using a single Nitrogen-Vacancy center
Abdelghani Laraoui,Jonathan S. Hodges,Carlos A. Meriles
Physics , 2010, DOI: 10.1063/1.3497004
Abstract: We report on the use of a single NV center to probe fluctuating AC magnetic fields. Using engineered currents to induce random changes in the field amplitude and phase, we show that stochastic fluctuations reduce the NV center sensitivity and, in general, make the NV response field-dependent. We also introduce two modalities to determine the field spectral composition, unknown a priori in a practical application. One strategy capitalizes on the generation of AC-field-induced coherence 'revivals', while the other approach uses the time-tagged fluorescence intensity record from successive NV observations to reconstruct the AC field spectral density. These studies are relevant for magnetic sensing in scenarios where the field of interest has a non-trivial, stochastic behavior, such as sensing unpolarized nuclear spin ensembles at low static magnetic fields.
The diamond Nitrogen-Vacancy center as a probe of random fluctuations in a nuclear spin ensemble
Abdelghani Laraoui,Jonathan S. Hodges,Colm Ryan,Carlos A. Meriles
Physics , 2011, DOI: 10.1103/PhysRevB.84.104301
Abstract: New schemes that exploit the unique properties of Nitrogen-Vacancy (NV) centers in diamond are presently being explored as a platform for high-resolution magnetic sensing. Here we focus on the ability of a NV center to monitor an adjacent mesoscopic nuclear spin bath. For this purpose, we conduct comparative experiments where the NV spin evolves under the influence of surrounding 13C nuclei or, alternatively, in the presence of asynchronous AC fields engineered to emulate bath fluctuations. Our study reveals substantial differences that underscore the limitations of the semi-classical picture when interpreting and predicting the outcome of experiments designed to probe small nuclear spin ensembles. In particular, our study elucidates the NV center response to bath fluctuations under common pulse sequences, and explores a detection protocol designed to probe time correlations of the nuclear spin bath dynamics. Further, we show that the presence of macroscopic nuclear spin order is key to the emergence of semi-classical spin magnetometry.
Universal Control of Nuclear Spins Via Anisotropic Hyperfine Interactions
Jonathan S. Hodges,Jamie C. Yang,Chandrasekhar Ramanathan,David G. Cory
Physics , 2007, DOI: 10.1103/PhysRevA.78.010303
Abstract: We show that nuclear spin subsystems can be completely controlled via microwave irradiation of resolved anisotropic hyperfine interactions with a nearby electron spin. Such indirect addressing of the nuclear spins via coupling to an electron allows us to create nuclear spin gates whose operational time is significantly faster than conventional direct addressing methods. We experimentally demonstrate the feasibility of this method on a solid-state ensemble system consisting of one electron and one nuclear spin.
Fidelity enhancement by logical qubit encoding
Michael K. Henry,Chandrasekhar Ramanathan,Jonathan S. Hodges,Colm A. Ryan,Michael J. Ditty,Raymond Laflamme,David G. Cory
Physics , 2007, DOI: 10.1103/PhysRevLett.99.220501
Abstract: We demonstrate coherent control of two logical qubits encoded in a decoherence free subspace (DFS) of four dipolar-coupled protons in an NMR quantum information processor. A pseudo-pure fiducial state is created in the DFS, and a unitary logical qubit entangling operator evolves the system to a logical Bell state. The four-spin molecule is partially aligned by a liquid crystal solvent, which introduces strong dipolar couplings among the spins. Although the system Hamiltonian is never fully specified, we demonstrate high fidelity control over the logical degrees of freedom. In fact, the DFS encoding leads to higher fidelity control than is available in the full four-spin Hilbert space.
Staphylococcus aureus Activates the NLRP3 Inflammasome in Human and Rat Conjunctival Goblet Cells
Victoria E. McGilligan, Meredith S. Gregory-Ksander, Dayu Li, Jonathan E. Moore, Robin R. Hodges, Michael S. Gilmore, Tara C. B. Moore, Darlene A. Dartt
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074010
Abstract: The conjunctiva is a moist mucosal membrane that is constantly exposed to an array of potential pathogens and triggers of inflammation. The NACHT, leucine rich repeat (LRR), and pyrin domain-containing protein 3 (NLRP3) is a Nod-like receptor that can sense pathogens or other triggers, and is highly expressed in wet mucosal membranes. NLRP3 is a member of the multi-protein complex termed the NLRP3 inflammasome that activates the caspase 1 pathway, inducing the secretion of biologically active IL-1β, a major initiator and promoter of inflammation. The purpose of this study was to: (1) determine whether NLRP3 is expressed in the conjunctiva and (2) determine whether goblet cells specifically contribute to innate mediated inflammation via secretion of IL-1β. We report that the receptors known to be involved in the priming and activation of the NLRP3 inflammasome, the purinergic receptors P2X4 and P2X7 and the bacterial Toll-like receptor 2 are present and functional in conjunctival goblet cells. Toxin-containing Staphylococcus aureus (S. aureus), which activates the NLRP3 inflammasome, increased the expression of the inflammasome proteins NLRP3, ASC and pro- and mature caspase 1 in conjunctival goblet cells. The biologically active form of IL-1β was detected in goblet cell culture supernatants in response to S. aureus, which was reduced when the cells were treated with the caspase 1 inhibitor Z-YVAD. We conclude that the NLRP3 inflammasome components are present in conjunctival goblet cells. The NRLP3 inflammasome appears to be activated in conjunctival goblet cells by toxin-containing S. aureus via the caspase 1 pathway to secrete mature IL1-β. Thus goblet cells contribute to the innate immune response in the conjunctiva by activation of the NLRP3 inflammasome.
Signatures of incoherence in a quantum information processor
Michael K. Henry,Alexey V. Gorshkov,Yaakov S. Weinstein,Paola Cappellaro,Joseph Emerson,Nicolas Boulant,Jonathan S. Hodges,Chandrasekhar Ramanathan,Timothy F. Havel,Rudy Martinez,David G. Cory
Physics , 2007,
Abstract: Incoherent noise is manifest in measurements of expectation values when the underlying ensemble evolves under a classical distribution of unitary processes. While many incoherent processes appear decoherent, there are important differences. The distribution functions underlying incoherent processes are either static or slowly varying with respect to control operations and so the errors introduced by these distributions are refocusable. The observation and control of incoherence in small Hilbert spaces is well known. Here we explore incoherence during an entangling operation, such as is relevant in quantum information processing. As expected, it is more difficult to separate incoherence and decoherence over such processes. However, by studying the fidelity decay under a cyclic entangling map we are able to identify distinctive experimental signatures of incoherence. This result is demonstrated both through numerical simulations and experimentally in a three qubit nuclear magnetic resonance implementation.
Single Color Centers Implanted in Diamond Nanostructures
Birgit J. M. Hausmann,Thomas M. Babinec,Jennifer T. Choy,Jonathan S. Hodges,Sungkun Hong,Irfan Bulu,A. Yacoby,M. D. Lukin,Marko Lon?ar
Physics , 2010, DOI: 10.1088/1367-2630/13/4/045004
Abstract: The development of materials processing techniques for optical diamond nanostructures containing a single color center is an important problem in quantum science and technology. In this work, we present the combination of ion implantation and top-down diamond nanofabrication in two scenarios: diamond nanopillars and diamond nanowires. The first device consists of a 'shallow' implant (~20nm) to generate Nitrogen-vacancy (NV) color centers near the top surface of the diamond crystal. Individual NV centers are then isolated mechanically by dry etching a regular array of nanopillars in the diamond surface. Photon anti-bunching measurements indicate that a high yield (>10%) of the devices contain a single NV center. The second device demonstrates 'deep' (~1\mu m) implantation of individual NV centers into pre-fabricated diamond nanowire. The high single photon flux of the nanowire geometry, combined with the low background fluorescence of the ultrapure diamond, allows us to sustain strong photon anti-bunching even at high pump powers.
Improved Bone Morphogenetic Protein-2 Retention in an Injectable Collagen Matrix Using Bifunctional Peptides
Paul T. Hamilton, Michelle S. Jansen, Sathya Ganesan, R. Edward Benson, Robin Hyde-DeRuyscher, Wayne F. Beyer, Joseph C. Gile, Shrikumar A. Nair, Jonathan A. Hodges, Hanne Gr?n
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0070715
Abstract: To promote healing of many orthopedic injuries, tissue engineering approaches are being developed that combine growth factors such as Bone Morphogenetic Proteins (BMP) with biomaterial carriers. Although these technologies have shown great promise, they still face limitations. We describe a generalized approach to create target-specific modular peptides that bind growth factors to implantable biomaterials. These bifunctional peptide coatings provide a novel way to modulate biology on the surface of an implant. Using phage display techniques, we have identified peptides that bind with high affinity to BMP-2. The peptides that bind to BMP-2 fall into two different sequence clusters. The first cluster of peptide sequences contains the motif W-X-X-F-X-X-L (where X can be any amino acid) and the second cluster contains the motif F-P-L-K-G. We have synthesized bifunctional peptide linkers that contain BMP-2 and collagen-binding domains. Using a rat ectopic bone formation model, we have injected rhBMP-2 into a collagen matrix with or without a bifunctional BMP-2: collagen peptide (BC-1). The presence of BC-1 significantly increased osteogenic cellular activity, the area of bone formed, and bone maturity at the site of injection. Our results suggest that bifunctional peptides that can simultaneously bind to a growth factor and an implantable biomaterial can be used to control the delivery and release of growth factors at the site of implantation.
Recommended isolated-line profile for representing high-resolution spectroscopic transitions (IUPAC Technical Report)
Jonathan Tennyson,Peter F. Bernath,Alain Campargue,Attila G. Csaszar,Ludovic Daumont,Robert R. Gamache,Joseph T. Hodges,Daniel Lisak,Olga V. Naumenko,Laurence S. Rothman,Ha Tran,Nikolai F. Zobov,Jeanna Buldyreva,Chris D. Boone,Maria Domenica De Vizia,Livio Gianfrani,Jean-Michel Hartmann,Robert McPheat,Jonathan Murray,Ngoc Hoa Ngo,Oleg L. Polyansky,Damien Weidmann
Physics , 2014, DOI: 10.1515/pac-2014-0208
Abstract: The report of an IUPAC Task Group, formed in 2011 on "Intensities and line shapes in high-resolution spectra of water isotopologues from experiment and theory" (Project No. 2011-022-2-100), on line profiles of isolated high-resolution rotational-vibrational transitions perturbed by neutral gas-phase molecules is presented. The well-documented inadequacies of the Voigt profile (VP), used almost universally by databases and radiative-transfer codes, to represent pressure effects and Doppler broadening in isolated vibrational-rotational and pure rotational transitions of the water molecule have resulted in the development of a variety of alternative line-profile models. These models capture more of the physics of the influence of pressure on line shapes but, in general, at the price of greater complexity. The Task Group recommends that the partially Correlated quadratic-Speed-Dependent Hard-Collision profile should be adopted as the appropriate model for high-resolution spectroscopy. For simplicity this should be called the Hartmann--Tran profile (HTP). The HTP is sophisticated enough to capture the various collisional contributions to the isolated line shape, can be computed in a straightforward and rapid manner, and reduces to simpler profiles, including the Voigt profile, under certain simplifying assumptions.
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