@article{1772, abstract = {We present the realization of a cavity quantum electrodynamics setup in which photons of strongly different lifetimes are engineered in different harmonic modes of the same cavity. We achieve this in a superconducting transmission line resonator with superconducting qubits coupled to the different modes. One cavity mode is strongly coupled to a detection line for qubit state readout, while a second long lifetime mode is used for photon storage and coherent quantum operations. We demonstrate sideband-based measurement of photon coherence, generation of n photon Fock states and the scaling of the sideband Rabi frequency with √n using a scheme that may be extended to realize sideband-based two-qubit logic gates.}, author = {Leek, Peter J and Baur, Matthias P and Johannes Fink and Bianchetti, R and Steffen, L. Kraig and Filipp, Stefan and Wallraff, Andreas}, journal = {Physical Review Letters}, number = {10}, publisher = {American Physical Society}, title = {{Cavity quantum electrodynamics with separate photon storage and qubit readout modes}}, doi = {10.1103/PhysRevLett.104.100504}, volume = {104}, year = {2010}, } @article{1773, abstract = {The quantum properties of electromagnetic, mechanical or other harmonic oscillators can be revealed by investigating their strong coherent coupling to a single quantum two level system in an approach known as cavity quantum electrodynamics (QED). At temperatures much lower than the characteristic energy level spacing the observation of vacuum Rabi oscillations or mode splittings with one or a few quanta asserts the quantum nature of the oscillator. Here, we study how the classical response of a cavity QED system emerges from the quantum one when its thermal occupation-or effective temperature-is raised gradually over 5 orders of magnitude. In this way we explore in detail the continuous quantum-to-classical crossover and demonstrate how to extract effective cavity field temperatures from both spectroscopic and time-resolved vacuum Rabi measurements.}, author = {Johannes Fink and Steffen, L. Kraig and Studer, Peter and Bishop, Lev S and Baur, Matthias P and Bianchetti, R and Bozyigit, Deniz and Lang, C and Filipp, Stefan and Leek, Peter J and Wallraff, Andreas}, journal = {Physical Review Letters}, number = {16}, publisher = {American Physical Society}, title = {{Quantum-to-classical transition in cavity quantum electrodynamics}}, doi = {10.1103/PhysRevLett.105.163601}, volume = {105}, year = {2010}, } @article{1774, abstract = {A number of superconducting qubits, such as the transmon or the phase qubit, have an energy level structure with small anharmonicity. This allows for convenient access of higher excited states with similar frequencies. However, special care has to be taken to avoid unwanted higher-level populations when using short control pulses. Here we demonstrate the preparation of arbitrary three level superposition states using optimal control techniques in a transmon. Performing dispersive readout, we extract the populations of all three levels of the qutrit and study the coherence of its excited states. Finally we demonstrate full quantum state tomography of the prepared qutrit states and evaluate the fidelities of a set of states, finding on average 95%.}, author = {Bianchetti, R and Filipp, Stefan and Baur, Matthias P and Johannes Fink and Lang, C and Steffen, L. Kraig and Boissonneault, Maxime and Blais, Alexandre and Wallraff, Andreas}, journal = {Physical Review Letters}, number = {22}, publisher = {American Physical Society}, title = {{Control and tomography of a three level superconducting artificial atom}}, doi = {10.1103/PhysRevLett.105.223601}, volume = {105}, year = {2010}, } @article{1800, abstract = {Retinitis pigmentosa refers to a diverse group of hereditary diseases that lead to incurable blindness, affecting two million people worldwide. As a common pathology, rod photoreceptors die early, whereas light-insensitive, morphologically altered cone photoreceptors persist longer. It is unknown if these cones are accessible for therapeutic intervention. Here, we show that expression of archaebacterial halorhodopsin in light-insensitive cones can substitute for the native phototransduction cascade and restore light sensitivity in mouse models of retinitis pigmentosa. Resensitized photoreceptors activate all retinal cone pathways, drive sophisticated retinal circuit functions (including directional selectivity), activate cortical circuits, and mediate visually guided behaviors. Using human ex vivo retinas, we show that halorhodopsin can reactivate light-insensitive human photoreceptors. Finally, we identified blind patients with persisting, light-insensitive cones for potential halorhodopsin-based therapy.}, author = {Busskamp, Volker and Duebel, Jens and Bálya, Dávid and Fradot, Mathias and Viney, Tim J and Sandra Siegert and Groner, Anna C and Cabuy, Erik and Forster, Valérie and Seeliger, Mathias W and Biel, Martin and Humphries, Peter and Pâques, Michel and Mohand-Saïd, Saddek and Trono, Didier and Deisseroth, Karl A and Sähel, José A and Picaud, Serge A and Roska, Botond M}, journal = {Science}, number = {5990}, pages = {413 -- 417}, publisher = {American Association for the Advancement of Science}, title = {{Genetic reactivation of cone photoreceptors restores visual responses in retinitis pigmentosa}}, doi = {10.1126/science.1190897}, volume = {329}, year = {2010}, } @article{18022, abstract = {The effect of the partial antiaromaticity of biphenylene on its substitution chemistry, its oxidation potential, and its single-molecule conductance is explored. Biphenylene and fluorene molecules with linkers of two amino groups or two cyclic thioether groups were synthesized and their conduction properties were investigated using scanning tunneling microscopy (STM) break-junction techniques and DFT calculations. Despite the partial antiaromaticity of biphenylene, which causes the biphenylenes to be much more easily oxidizable, no significant increase in molecular conductance was found.}, author = {Schneebeli, Severin and Kamenetska, Maria and Foss, Frank and Vazquez, Hector and Skouta, Rachid and Hybertsen, Mark and Venkataraman, Latha and Breslow, Ronald}, issn = {1523-7052}, journal = {Organic Letters}, number = {18}, pages = {4114--4117}, publisher = {American Chemical Society}, title = {{The electrical properties of biphenylenes}}, doi = {10.1021/ol1017036}, volume = {12}, year = {2010}, } @article{18023, abstract = {We measure the conductance of single Au−molecule−Au junctions with a series of air-stable diphenylphosphine-terminated molecules using the scanning tunneling microscope-based break junction technique. Thousands of conductance versus displacement traces collected for each molecule are used to statistically analyze junction conductance and evolution upon elongation. Measured conductances for a series of alkane-based molecules exhibit an exponential decrease with increasing length, as expected for saturated molecules, with a tunneling decay constant of 0.98 ± 0.04. Measurements of junction elongation indicate strong metal−molecule binding, with a length that increases with the number of methylene groups in the backbone. Measured conductance histograms for four molecules with short, unsaturated backbones (e.g., benzene) are much broader with less well-defined peaks. These measurements are supported by density function theory calculations. The phosphine binds selectively to under-coordinated gold atoms through a donor−acceptor bond with a binding energy of about 1 eV. The calculated tunnel coupling correlates very well with experiment.}, author = {Parameswaran, R. and Widawsky, J. R. and Vázquez, H. and Park, Y. S. and Boardman, B. M. and Nuckolls, C. and Steigerwald, M. L. and Hybertsen, M. S. and Venkataraman, Latha}, issn = {1948-7185}, journal = {The Journal of Physical Chemistry Letters}, number = {14}, pages = {2114--2119}, publisher = {American Chemical Society}, title = {{Reliable formation of single molecule junctions with air-stable diphenylphosphine linkers}}, doi = {10.1021/jz100656s}, volume = {1}, year = {2010}, } @article{18024, abstract = {Using photoemission spectroscopy, we determine the relationship between electronic energy level alignment at a metal−molecule interface and single-molecule junction transport data. We measure the position of the highest occupied molecular orbital (HOMO) relative to the Au metal Fermi level for three 1,4-benzenediamine derivatives on Au(111) and Au(110) with ultraviolet and resonant X-ray photoemission spectroscopy. We compare these results to scanning tunnelling microscope-based break-junction measurements of single molecule conductance and to first-principles calculations. We find that the energy difference between the HOMO and Fermi level for the three molecules adsorbed on Au(111) correlate well with changes in conductance and agree well with quasiparticle energies computed from first-principles calculations incorporating self-energy corrections. On the Au(110) that presents Au atoms with lower-coordination, critical in break-junction conductance measurements, we see that the HOMO level shifts further from the Fermi level. These results provide the first direct comparison of spectroscopic energy level alignment measurements with single molecule junction transport data.}, author = {Dell’Angela, M. and Kladnik, G. and Cossaro, A. and Verdini, A. and Kamenetska, M. and Tamblyn, I. and Quek, S. Y. and Neaton, J. B. and Cvetko, D. and Morgante, A. and Venkataraman, Latha}, issn = {1530-6992}, journal = {Nano Letters}, number = {7}, pages = {2470--2474}, publisher = {American Chemical Society}, title = {{Relating energy level alignment and amine-linked single molecule junction conductance}}, doi = {10.1021/nl100817h}, volume = {10}, year = {2010}, } @article{18027, abstract = {We have measured the conductance and characterized molecule−electrode binding geometries of four pyridine-terminated molecules by elongating and then compressing gold point contacts in a solution of molecules. We have found that all pyridine-terminated molecules exhibit bistable conductance signatures, signifying that the nature of the pyridine−gold bond allows two distinct conductance states that are accessed as the gold−molecule−gold junction is elongated. We have identified the low-conductance state as corresponding to a molecule fully stretched out between the gold electrodes, where the distance between contacts correlates with the length of the molecule; the high-conductance state is due to a molecule bound at an angle. For all molecules, we have found that the distribution of junction elongations in the low-conductance state is the same, while in the high-conductance state, the most likely elongation length increases linearly with molecule length. The results of first-principles conductance calculations for the four molecules in the low-conductance geometry agree well with the experimental results and show that the dominant conducting channel in the conjugated pyridine-linked molecules is through the π* orbital.}, author = {Kamenetska, M. and Quek, Su Ying and Whalley, A. C. and Steigerwald, M. L. and Choi, H. J. and Louie, Steven G. and Nuckolls, C. and Hybertsen, M. S. and Neaton, J. B. and Venkataraman, Latha}, issn = {1520-5126}, journal = {Journal of the American Chemical Society}, number = {19}, pages = {6817--6821}, publisher = {American Chemical Society}, title = {{Conductance and geometry of pyridine-linked single-molecule junctions}}, doi = {10.1021/ja1015348}, volume = {132}, year = {2010}, } @inproceedings{18338, abstract = {Invariant image descriptors play an important role in many computer vision and pattern recognition problems such as image search and retrieval. A dominant paradigm today is that of “bags of features”, a representation of images as distributions of primitive visual elements. The main disadvantage of this approach is the loss of spatial relations between features, which often carry important information about the image. In this paper, we show how to construct spatially-sensitive image descriptors in which both the features and their relation are affine-invariant. Our construction is based on a vocabulary of pairs of features coupled with a vocabulary of invariant spatial relations between the features. Experimental results show the advantage of our approach in image retrieval applications.}, author = {Bronstein, Alexander and Bronstein, Michael M.}, booktitle = {11th European Conference on Computer Vision}, isbn = {9783642155512}, issn = {1611-3349}, location = {Heraklion, Greece}, pages = {197–208}, publisher = {Springer Nature}, title = {{Spatially-sensitive affine-invariant image descriptors}}, doi = {10.1007/978-3-642-15552-9_15}, volume = {6312}, year = {2010}, } @inproceedings{18339, abstract = {Automatic detection of symmetries, regularity, and repetitive structures in 3D geometry is a fundamental problem in shape analysis and pattern recognition with applications in computer vision and graphics. Especially challenging is to detect intrinsic regularity, where the repetitions are on an intrinsic grid, without any apparent Euclidean pattern to describe the shape, but rising out of (near) isometric deformation of the underlying surface. In this paper, we employ multidimensional scaling to reduce the problem of intrinsic structure detection to a simpler problem of 2D grid detection. Potential 2D grids are then identified using an autocorrelation analysis, refined using local fitting, validated, and finally projected back to the spatial domain. We test the detection algorithm on a variety of scanned plaster models in presence of imperfections like missing data, noise and outliers. We also present a range of applications including scan completion, shape editing, super-resolution, and structural correspondence.}, author = {Mitra, Niloy J. and Bronstein, Alexander and Bronstein, Michael}, booktitle = {11th European Conference on Computer Vision}, isbn = {9783642155574}, issn = {0302-9743}, location = {Heraklion, Greece}, pages = {398–410}, publisher = {Springer Nature}, title = {{Intrinsic regularity detection in 3D geometry}}, doi = {10.1007/978-3-642-15558-1_29}, volume = {6313}, year = {2010}, } @article{18358, abstract = {In this paper, the problem of non-rigid shape recognition is studied from the perspective of metric geometry. In particular, we explore the applicability of diffusion distances within the Gromov-Hausdorff framework. While the traditionally used geodesic distance exploits the shortest path between points on the surface, the diffusion distance averages all paths connecting the points. The diffusion distance constitutes an intrinsic metric which is robust, in particular, to topological changes. Such changes in the form of shortcuts, holes, and missing data may be a result of natural non-rigid deformations as well as acquisition and representation noise due to inaccurate surface construction. The presentation of the proposed framework is complemented with examples demonstrating that in addition to the relatively low complexity involved in the computation of the diffusion distances between surface points, its recognition and matching performances favorably compare to the classical geodesic distances in the presence of topological changes between the non-rigid shapes.}, author = {Bronstein, Alexander and Bronstein, Michael M. and Kimmel, Ron and Mahmoudi, Mona and Sapiro, Guillermo}, issn = {1573-1405}, journal = {International Journal of Computer Vision}, number = {2-3}, pages = {266--286}, publisher = {Springer Nature}, title = {{A Gromov-Hausdorff framework with diffusion geometry for topologically-robust non-rigid shape matching}}, doi = {10.1007/s11263-009-0301-6}, volume = {89}, year = {2010}, } @article{18359, abstract = {Symmetry and self-similarity are the cornerstone of Nature, exhibiting themselves through the shapes of natural creations and ubiquitous laws of physics. Since many natural objects are symmetric, the absence of symmetry can often be an indication of some anomaly or abnormal behavior. Therefore, detection of asymmetries is important in numerous practical applications, including crystallography, medical imaging, and face recognition, to mention a few. Conversely, the assumption of underlying shape symmetry can facilitate solutions to many problems in shape reconstruction and analysis. Traditionally, symmetries are described as extrinsic geometric properties of the shape. While being adequate for rigid shapes, such a description is inappropriate for non-rigid ones: extrinsic symmetry can be broken as a result of shape deformations, while its intrinsic symmetry is preserved. In this paper, we present a generalization of symmetries for non-rigid shapes and a numerical framework for their analysis, addressing the problems of full and partial exact and approximate symmetry detection and classification.}, author = {Raviv, Dan and Bronstein, Alexander and Bronstein, Michael M. and Kimmel, Ron}, issn = {1573-1405}, journal = {International Journal of Computer Vision}, pages = {18--39}, publisher = {Springer Nature}, title = {{Full and partial symmetries of non-rigid shapes}}, doi = {10.1007/s11263-010-0320-3}, volume = {89}, year = {2010}, } @article{18360, abstract = {Many manifold learning procedures try to embed a given feature data into a flat space of low dimensionality while preserving as much as possible the metric in the natural feature space. The embedding process usually relies on distances between neighboring features, mainly since distances between features that are far apart from each other often provide an unreliable estimation of the true distance on the feature manifold due to its non-convexity. Distortions resulting from using long geodesics indiscriminately lead to a known limitation of the Isomap algorithm when used to map non-convex manifolds. Presented is a framework for nonlinear dimensionality reduction that uses both local and global distances in order to learn the intrinsic geometry of flat manifolds with boundaries. The resulting algorithm filters out potentially problematic distances between distant feature points based on the properties of the geodesics connecting those points and their relative distance to the boundary of the feature manifold, thus avoiding an inherent limitation of the Isomap algorithm. Since the proposed algorithm matches non-local structures, it is robust to strong noise. We show experimental results demonstrating the advantages of the proposed approach over conventional dimensionality reduction techniques, both global and local in nature.}, author = {Rosman, Guy and Bronstein, Michael M. and Bronstein, Alexander and Kimmel, Ron}, issn = {1573-1405}, journal = {International Journal of Computer Vision}, pages = {56--68}, publisher = {Springer Nature}, title = {{Nonlinear dimensionality reduction by topologically constrained isometric embedding}}, doi = {10.1007/s11263-010-0322-1}, volume = {89}, year = {2010}, } @inproceedings{18376, abstract = {Visual understanding is often based on measuring similarity between observations. Learning similarities specific to a certain perception task from a set of examples has been shown advantageous in various computer vision and pattern recognition problems. In many important applications, the data that one needs to compare come from different representations or modalities, and the similarity between such data operates on objects that may have different and often incommensurable structure and dimensionality. In this paper, we propose a framework for supervised similarity learning based on embedding the input data from two arbitrary spaces into the Hamming space. The mapping is expressed as a binary classification problem with positive and negative examples, and can be efficiently learned using boosting algorithms. The utility and efficiency of such a generic approach is demonstrated on several challenging applications including cross-representation shape retrieval and alignment of multi-modal medical images.}, author = {Bronstein, Michael M. and Bronstein, Alexander and Michel, Fabrice and Paragios, Nikos}, booktitle = {2010 IEEE Computer Society Conference on Computer Vision and Pattern Recognition}, issn = {1063-6919 }, location = {San Francisco, CA, USA}, pages = {3594 -- 3601}, publisher = {IEEE}, title = {{Data fusion through cross-modality metric learning using similarity-sensitive hashing}}, doi = {10.1109/cvpr.2010.5539928}, year = {2010}, } @inproceedings{18432, abstract = {Invariant shape descriptors are instrumental in numerous shape analysis tasks including deformable shape comparison, registration, classification, and retrieval. Most existing constructions model a 3D shape as a two-dimensional surface describing the shape boundary, typically represented as a triangular mesh or a point cloud. Using intrinsic properties of the surface, invariant descriptors can be designed. One such example is the recently introduced heat kernel signature, based on the Laplace-Beltrami operator of the surface. In many applications, however, a volumetric shape model is more natural and convenient. Moreover, modeling shape deformations as approximate isometries of the volume of an object, rather than its boundary, better captures natural behavior of non-rigid deformations in many cases. Here, we extend the idea of heat kernel signature to robust isometry-invariant volumetric descriptors, and show their utility in shape retrieval. The proposed approach achieves state-of-the-art results on the SHREC 2010 large-scale shape retrieval benchmark.}, author = {Raviv, Dan and Bronstein, Michael M. and Bronstein, Alexander and Kimmel, Ron}, booktitle = {Proceedings of the ACM workshop on 3D object retrieval}, isbn = {9781450301602}, location = {Firenze, Italy}, pages = {39 -- 44}, publisher = {ACM}, title = {{Volumetric heat kernel signatures}}, doi = {10.1145/1877808.1877817}, year = {2010}, } @article{22029, abstract = {We consider two classes of defocusing energy-supercritical nonlinear Schrödinger equations in dimensions d ≥ 5. We prove that if the solution u is a priori bounded in the critical Sobolev space, that is, {mathematical formular} , then u is global and scatters.}, author = {Killip, Rowan and Visan, Monica}, issn = {1532-4133}, journal = {Communications in Partial Differential Equations}, keywords = {critical regularity, Nonlinear Schrödinger equations}, number = {6}, pages = {945--987}, publisher = {Informa UK Limited}, title = {{Energy-supercritical NLS: Critical [Hdot]^s-bounds imply scattering}}, doi = {10.1080/03605301003717084}, volume = {35}, year = {2010}, } @article{22089, abstract = {We consider the focusing energy-critical nonlinear Schr\"odinger equation $iu_t+\Delta u = - |u|^{4\over{d-2}}u$ in dimensions $d\geq 5$. We prove that if a maximal-lifespan solution $u\colon \ I\times {\Bbb R}^d\to {\Bbb C}$ obeys $\sup_{t\in I}\|\nabla u(t)\|_2<\|\nabla W\|_2$, then it is global and scatters both forward and backward in time. Here $W$ denotes the ground state, which is a stationary solution of the equation. In particular, if a solution has both energy and kinetic energy less than those of the ground state $W$ at some point in time, then the solution is global and scatters. We also show that any solution that blows up with bounded kinetic energy must concentrate at least the kinetic energy of the ground state. Similar results were obtained by Kenig and Merle for spherically symmetric initial data and dimensions $d=3,4,5$. }, author = {Killip, Rowan and Visan, Monica}, issn = {1080-6377}, journal = {American Journal of Mathematics}, number = {2}, pages = {361--424}, publisher = {Johns Hopkins University Press}, title = {{The focusing energy-critical nonlinear Schrödinger equation in dimensions five and higher}}, doi = {10.1353/ajm.0.0107}, volume = {132}, year = {2010}, } @article{3867, abstract = {Weighted automata are nondeterministic automata with numerical weights on transitions. They can define quantitative languages L that assign to each word w a real number L(w). In the case of infinite words, the value of a run is naturally computed as the maximum, limsup, liminf, limit-average, or discounted-sum of the transition weights. The value of a word w is the supremum of the values of the runs over w. We study expressiveness and closure questions about these quantitative languages. We first show that the set of words with value greater than a threshold can be omega-regular for deterministic limit-average and discounted-sum automata, while this set is always omega-regular when the threshold is isolated (i.e., some neighborhood around the threshold contains no word). In the latter case, we prove that the omega-regular language is robust against small perturbations of the transition weights. We next consider automata with transition weights 0 or 1 and show that they are as expressive as general weighted automata in the limit-average case, but not in the discounted-sum case. Third, for quantitative languages L-1 and L-2, we consider the operations max(L-1, L-2), min(L-1, L-2), and 1 - L-1, which generalize the boolean operations on languages, as well as the sum L-1 + L-2. We establish the closure properties of all classes of quantitative languages with respect to these four operations.}, author = {Chatterjee, Krishnendu and Doyen, Laurent and Henzinger, Thomas A}, journal = {Logical Methods in Computer Science}, number = {3}, pages = {1 -- 23}, publisher = {International Federation for Computational Logic}, title = {{Expressiveness and closure properties for quantitative languages}}, doi = {10.2168/LMCS-6(3:10)2010}, volume = {6}, year = {2010}, } @article{3868, abstract = {Simulation and bisimulation metrics for stochastic systems provide a quantitative generalization of the classical simulation and bisimulation relations. These metrics capture the similarity of states with respect to quantitative specifications written in the quantitative mu-calculus and related probabilistic logics. We first show that the metrics provide a bound for the difference in long-run average and discounted average behavior across states, indicating that the metrics can be used both in system verification, and in performance evaluation. For turn-based games and MDPs, we provide a polynomial-time algorithm for the computation of the one-step metric distance between states. The algorithm is based on linear programming; it improves on the previous known exponential-time algorithm based on a reduction to the theory of reals. We then present PSPACE algorithms for both the decision problem and the problem of approximating the metric distance between two states, matching the best known algorithms for Markov chains. For the bisimulation kernel of the metric our algorithm works in time O(n(4)) for both turn-based games and MDPs; improving the previously best known O(n(9).log(n)) time algorithm for MDPs. For a concurrent game G, we show that computing the exact distance be tween states is at least as hard as computing the value of concurrent reachability games and the square-root-sum problem in computational geometry. We show that checking whether the metric distance is bounded by a rational r, can be done via a reduction to the theory of real closed fields, involving a formula with three quantifier alternations, yielding O(vertical bar G vertical bar(O(vertical bar G vertical bar 5))) time complexity, improving the previously known reduction, which yielded O(vertical bar G vertical bar(O(vertical bar G vertical bar 7))) time complexity. These algorithms can be iterated to approximate the metrics using binary search}, author = {Chatterjee, Krishnendu and De Alfaro, Luca and Majumdar, Ritankar and Raman, Vishwanath}, journal = {Logical Methods in Computer Science}, number = {3}, pages = {1 -- 27}, publisher = {International Federation for Computational Logic}, title = {{Algorithms for game metrics}}, doi = {10.2168/LMCS-6(3:13)2010}, volume = {6}, year = {2010}, } @inproceedings{3782, abstract = {In cortex surface segmentation, the extracted surface is required to have a particular topology, namely, a two-sphere. We present a new method for removing topology noise of a curve or surface within the level set framework, and thus produce a cortical surface with correct topology. We define a new energy term which quantifies topology noise. We then show how to minimize this term by computing its functional derivative with respect to the level set function. This method differs from existing methods in that it is inherently continuous and not digital; and in the way that our energy directly relates to the topology of the underlying curve or surface, versus existing knot-based measures which are related in a more indirect fashion. The proposed flow is validated empirically.}, author = {Chen, Chao and Freedman, Daniel}, booktitle = {Conference proceedings MCV 2010}, location = {Beijing, China}, pages = {31 -- 42}, publisher = {Springer}, title = {{Topology noise removal for curve and surface evolution}}, doi = {10.1007/978-3-642-18421-5_4}, volume = {6533}, year = {2010}, }