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Results for "Pravesh Kothari"

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Almost Optimal Pseudorandom Generators for Spherical CapsNov 23 2014Mar 26 2015Halfspaces or linear threshold functions are widely studied in complexity theory, learning theory and algorithm design. In this work we study the natural problem of constructing pseudorandom generators (PRGs) for halfspaces over the sphere, aka spherical ... More
On the Expressive Power of Kernel Methods and the Efficiency of Kernel Learning by Association SchemesFeb 13 2019We study the expressive power of kernel methods and the algorithmic feasibility of multiple kernel learning for a special rich class of kernels. Specifically, we define \emph{Euclidean kernels}, a diverse class that includes most, if not all, families ... More
Better Agnostic Clustering Via Relaxed Tensor NormsNov 20 2017We develop a new family of convex relaxations for $k$-means clustering based on sum-of-squares norms, a relaxation of the injective tensor norm that is efficiently computable using the Sum-of-Squares algorithm. We give an algorithm based on this relaxation ... More
SOS lower bounds with hard constraints: think global, act localSep 04 2018Many previous Sum-of-Squares (SOS) lower bounds for CSPs had two deficiencies related to global constraints. First, they were not able to support a "cardinality constraint", as in, say, the Min-Bisection problem. Second, while the pseudoexpectation of ... More
List-Decodable Linear RegressionMay 14 2019We give the first polynomial-time algorithm for robust regression in the list-decodable setting where an adversary can corrupt a greater than $1/2$ fraction of examples. For any $\alpha < 1$, our algorithm takes as input a sample $\{ (x_i,y_i)\}_{i \leq ... More
List-Decodable Linear RegressionMay 14 2019May 15 2019We give the first polynomial-time algorithm for robust regression in the list-decodable setting where an adversary can corrupt a greater than $1/2$ fraction of examples. For any $\alpha < 1$, our algorithm takes as input a sample $\{ (x_i,y_i)\}_{i \leq ... More
Sum of squares lower bounds for refuting any CSPJan 17 2017Let $P:\{0,1\}^k \to \{0,1\}$ be a nontrivial $k$-ary predicate. Consider a random instance of the constraint satisfaction problem $\mathrm{CSP}(P)$ on $n$ variables with $\Delta n$ constraints, each being $P$ applied to $k$ randomly chosen literals. ... More
Approximation Schemes for a Buyer with Independent Items via SymmetriesMay 13 2019We consider a revenue-maximizing seller with $n$ items facing a single buyer. We introduce the notion of $symmetric~menu~complexity$ of a mechanism, which counts the number of distinct options the buyer may purchase, up to permutations of the items. Our ... More
Agnostic Learning by RefutingSep 12 2017Nov 30 2017The sample complexity of learning a Boolean-valued function class is precisely characterized by its Rademacher complexity. This has little bearing, however, on the sample complexity of \emph{efficient} agnostic learning. We introduce \emph{refutation ... More
An Analysis of the t-SNE Algorithm for Data VisualizationMar 05 2018Jun 06 2018A first line of attack in exploratory data analysis is data visualization, i.e., generating a 2-dimensional representation of data that makes clusters of similar points visually identifiable. Standard Johnson-Lindenstrauss dimensionality reduction does ... More
Nearly Tight Bounds on $\ell_1$ Approximation of Self-Bounding FunctionsApr 18 2014We study the complexity of learning and approximation of self-bounding functions over the uniform distribution on the Boolean hypercube ${0,1}^n$. Informally, a function $f:{0,1}^n \rightarrow \mathbb{R}$ is self-bounding if for every $x \in {0,1}^n$, ... More
Provable Submodular Minimization using Wolfe's AlgorithmNov 01 2014Owing to several applications in large scale learning and vision problems, fast submodular function minimization (SFM) has become a critical problem. Theoretically, unconstrained SFM can be performed in polynomial time [IFF 2001, IO 2009]. However, these ... More
Differentially Private Online LearningSep 01 2011Sep 16 2011In this paper, we consider the problem of preserving privacy in the online learning setting. We study the problem in the online convex programming (OCP) framework---a popular online learning setting with several interesting theoretical and practical implications---while ... More
Approximating Rectangles by Juntas and Weakly-Exponential Lower Bounds for LP Relaxations of CSPsOct 09 2016Oct 11 2016We show that sub-exponential size ($\exp(n^{c})$ for constants $0 < c < 1$) linear programming relaxations cannot beat random guessing for approximately satisfying constraint satisfaction problems (CSPs). In fact, we show that for such problems, sub-exponential ... More
Representation, Approximation and Learning of Submodular Functions Using Low-rank Decision TreesApr 02 2013We study the complexity of approximate representation and learning of submodular functions over the uniform distribution on the Boolean hypercube $\{0,1\}^n$. Our main result is the following structural theorem: any submodular function is $\epsilon$-close ... More
Approximating Rectangles by Juntas and Weakly-Exponential Lower Bounds for LP Relaxations of CSPsOct 09 2016Nov 20 2016We show that for constraint satisfaction problems (CSPs), sub-exponential size linear programming relaxations are as powerful as $n^{\Omega(1)}$-rounds of the Sherali-Adams linear programming hierarchy. As a corollary, we obtain sub-exponential size lower ... More
Sum of Squares Lower Bounds from Pairwise IndependenceJan 04 2015Mar 26 2015We prove that for every $\epsilon>0$ and predicate $P:\{0,1\}^k\rightarrow \{0,1\}$ that supports a pairwise independent distribution, there exists an instance $\mathcal{I}$ of the $\mathsf{Max}P$ constraint satisfaction problem on $n$ variables such ... More
Surprise in ElectionsJan 30 2018Elections involving a very large voter population often lead to outcomes that surprise many. This is particularly important for the elections in which results affect the economy of a sizable population. A better prediction of the true outcome helps reduce ... More
Submodular Functions Are Noise StableJun 02 2011Jun 13 2011We show that all non-negative submodular functions have high {\em noise-stability}. As a consequence, we obtain a polynomial-time learning algorithm for this class with respect to any product distribution on $\{-1,1\}^n$ (for any constant accuracy parameter ... More
SoS and Planted Clique: Tight Analysis of MPW Moments at all Degrees and an Optimal Lower Bound at Degree FourJul 18 2015The problem of finding large cliques in random graphs and its "planted" variant, where one wants to recover a clique of size $\omega \gg \log{(n)}$ added to an \Erdos-\Renyi graph $G \sim G(n,\frac{1}{2})$, have been intensely studied. Nevertheless, existing ... More
Communication with Contextual UncertaintyApr 19 2015Jul 19 2015We introduce a simple model illustrating the role of context in communication and the challenge posed by uncertainty of knowledge of context. We consider a variant of distributional communication complexity where Alice gets some information $x$ and Bob ... More
An optimal quantum algorithm for the oracle identification problemNov 29 2013Jan 06 2014In the oracle identification problem, we are given oracle access to an unknown N-bit string x promised to belong to a known set C of size M and our task is to identify x. We present a quantum algorithm for the problem that is optimal in its dependence ... More
Generating Near-Bipartite BricksNov 23 2016A $3$-connected graph $G$ is a brick if, for any two vertices $u$ and $v$, the graph $G-\{u,v\}$ has a perfect matching. Deleting an edge $e$ from a brick $G$ results in a graph with zero, one or two vertices of degree two. The bicontraction of a vertex ... More
Nearly optimal separations between communication (or query) complexity and partitionsDec 03 2015We show a nearly quadratic separation between deterministic communication complexity and the logarithm of the partition number, which is essentially optimal. This improves upon a recent power 1.5 separation of G\"o\"os, Pitassi, and Watson (FOCS 2015). ... More
A Model for Dipole Modulation of CMBR PolarizationAug 13 2015Oct 05 2015I propose a model of dipole modulation in Cosmic Background Microwave Radiation (CMBR) polarization fields Q and U. It is shown that the modulation leads to correlations between l and l multipoles where either l = l or l = l \pm 1, but the contribution ... More
A Nearly Tight Sum-of-Squares Lower Bound for the Planted Clique ProblemApr 11 2016Apr 12 2016We prove that with high probability over the choice of a random graph $G$ from the Erd\H{o}s-R\'enyi distribution $G(n,1/2)$, the $n^{O(d)}$-time degree $d$ Sum-of-Squares semidefinite programming relaxation for the clique problem will give a value of ... More
The power of sum-of-squares for detecting hidden structuresOct 13 2017We study planted problems---finding hidden structures in random noisy inputs---through the lens of the sum-of-squares semidefinite programming hierarchy (SoS). This family of powerful semidefinite programs has recently yielded many new algorithms for ... More
A Comprehensive Study On The Applications Of Machine Learning For Diagnosis Of CancerMay 06 2015Sep 28 2015Collectively, lung cancer, breast cancer and melanoma was diagnosed in over 535,340 people out of which, 209,400 deaths were reported [13]. It is estimated that over 600,000 people will be diagnosed with these forms of cancer in 2015. Most of the deaths ... More
B-Mode auto-bispectrum due to matter bounceJan 19 2019Apr 15 2019In this article, we investigate CMB B-mode auto-bispectrum due to matter bounce Universe. It is known that this mode can only be generated by tensor perturbations, i.e., the gravity waves. For simplicity, we study the B-modes in a minimally coupled Einstein ... More
On Feature Reduction using Deep Learning for Trend Prediction in FinanceApr 11 2017One of the major advantages in using Deep Learning for Finance is to embed a large collection of information into investment decisions. A way to do that is by means of compression, that lead us to consider a smaller feature space. Several studies are ... More
Event-Flow Graphs for Efficient Path-Sensitive AnalysesApr 04 2014Mar 08 2015Efficient and accurate path-sensitive analyses pose the challenges of: (a) analyzing an exponentially-increasing number of paths in a control-flow graph (CFG), and (b) checking feasibility of paths in a CFG. We address these challenges by introducing ... More
A Machine Checked Model of Idempotent MGU Axioms For Lists of Equational ConstraintsDec 22 2010We present formalized proofs verifying that the first-order unification algorithm defined over lists of satisfiable constraints generates a most general unifier (MGU), which also happens to be idempotent. All of our proofs have been formalized in the ... More
Regression Driven F--Transform and Application to Smoothing of Financial Time SeriesMay 04 2017In this paper we propose to extend the definition of fuzzy transform in order to consider an interpolation of models that are richer than the standard fuzzy transform. We focus on polynomial models, linear in particular, although the approach can be easily ... More
Quantum query complexity of minor-closed graph propertiesNov 05 2010May 19 2011We study the quantum query complexity of minor-closed graph properties, which include such problems as determining whether an $n$-vertex graph is planar, is a forest, or does not contain a path of a given length. We show that most minor-closed properties---those ... More
Reinforcement Learning with Parameterized ActionsSep 05 2015Nov 26 2015We introduce a model-free algorithm for learning in Markov decision processes with parameterized actions-discrete actions with continuous parameters. At each step the agent must select both which action to use and which parameters to use with that action. ... More
An Alternative Estimation of Market Volatility based on Fuzzy TransformMay 03 2017Realization of uncertainty of prices is captured by volatility, that is the tendency of prices to vary along a period of time. This is generally measured as standard deviation of daily returns. In this paper we propose and investigate the application ... More
Randomized query complexity of sabotaged and composed functionsMay 29 2016We study the composition question for bounded-error randomized query complexity: Is R(f o g) = Omega(R(f) R(g)) for all Boolean functions f and g? We show that inserting a simple Boolean function h, whose query complexity is only Theta(log R(g)), in between ... More
Localization and instability in sheared granular materials: Role of friction and vibrationJul 18 2016Shear banding and stick-slip instabilities have been long observed in sheared granular materials. Yet, their microscopic underpinnings, interdependencies and variability under different loading conditions have not been fully explored. Here, we use a non-equilibrium ... More
Randomized query complexity of sabotaged and composed functionsMay 29 2016Dec 05 2016We study the composition question for bounded-error randomized query complexity: Is R(f o g) = Omega(R(f) R(g)) for all Boolean functions f and g? We show that inserting a simple Boolean function h, whose query complexity is only Theta(log R(g)), in between ... More
Limitations on the simulation of non-sparse HamiltoniansAug 31 2009Mar 19 2010The problem of simulating sparse Hamiltonians on quantum computers is well studied. The evolution of a sparse N x N Hamiltonian H for time t can be simulated using O(||Ht||poly(log N)) operations, which is essentially optimal due to a no--fast-forwarding ... More
Per-Tone model for Common Mode sensor based alien noise cancellation for Downstream xDSLJul 05 2017For xDSL systems, alien noise cancellation using an additional common mode sensor at the downstream receiver can be thought of as interference cancellation in a Single Input Dual Output (SIDO) system. The coupling between the common mode and differential ... More
Simulating sparse Hamiltonians with star decompositionsMar 18 2010Nov 05 2010We present an efficient algorithm for simulating the time evolution due to a sparse Hamiltonian. In terms of the maximum degree d and dimension N of the space on which the Hamiltonian H acts for time t, this algorithm uses (d^2(d+log* N)||Ht||)^{1+o(1)} ... More
Quantum distinguishing complexity, zero-error algorithms, and statistical zero knowledgeFeb 10 2019We define a new query measure we call quantum distinguishing complexity, denoted QD(f) for a Boolean function f. Unlike a quantum query algorithm, which must output a state close to |0> on a 0-input and a state close to |1> on a 1-input, a "quantum distinguishing ... More
Dequantizing read-once quantum formulasApr 18 2013Quantum formulas, defined by Yao [FOCS '93], are the quantum analogs of classical formulas, i.e., classical circuits in which all gates have fanout one. We show that any read-once quantum formula over a gate set that contains all single-qubit gates is ... More
Separating decision tree complexity from subcube partition complexityApr 06 2015The subcube partition model of computation is at least as powerful as decision trees but no separation between these models was known. We show that there exists a function whose deterministic subcube partition complexity is asymptotically smaller than ... More
Distributed Representations for Biological Sequence AnalysisAug 21 2016Sep 12 2016Biological sequence comparison is a key step in inferring the relatedness of various organisms and the functional similarity of their components. Thanks to the Next Generation Sequencing efforts, an abundance of sequence data is now available to be processed ... More
Nested Quantum Walks with Quantum Data StructuresOct 03 2012We develop a new framework that extends the quantum walk framework of Magniez, Nayak, Roland, and Santha, by utilizing the idea of quantum data structures to construct an efficient method of nesting quantum walks. Surprisingly, only classical data structures ... More
Study of Aqueous Dispersions of Magnetic Nanoparticles by Magnetic and Rheological MeasurementsFeb 19 2016The observed magnetic tunability of light transmission through a ferrofluid can be effectively understood in terms of the inter-particle interaction that can be estimated from the magnetic and rheological properties of these fluids. The present study ... More
Engineering Enhanced Thermal Transport in Layered NanomaterialsOct 05 2017A comprehensive rational thermal material design paradigm requires the ability to reduce and enhance the thermal conductivities of nanomaterials. In contrast to the existing ability to reduce the thermal conductivity, methods that allow to enhance heat ... More
Cosmological Power Spectrum in Non-commutative Space-timeFeb 28 2015Feb 16 2016We propose a generalized star product which deviates from the standard product when the fields at evaluated at different space-time points. This produces no changes in the standard Lagrangian density in non-commutative space-time but produces a change ... More
Collaborative Sampling in Generative Adversarial NetworksFeb 02 2019Apr 19 2019A standard practice in Generative Adversarial Networks (GANs) is to completely discard the discriminator when generating samples. However, this sampling method loses valuable information learned by the discriminator regarding the data distribution. In ... More
Separations in query complexity using cheat sheetsNov 05 2015We show a power 2.5 separation between bounded-error randomized and quantum query complexity for a total Boolean function, refuting the widely believed conjecture that the best such separation could only be quadratic (from Grover's algorithm). We also ... More
Approximation Algorithms for Digraph Width ParametersJul 25 2011Feb 05 2013Several problems that are NP-hard on general graphs are efficiently solvable on graphs with bounded treewidth. Efforts have been made to generalize treewidth and the related notion of pathwidth to digraphs. Directed treewidth, DAG-width and Kelly-width ... More
Improving TCP Performance over Wireless Network with Frequent DisconnectionsDec 09 2011Presented in this paper is the solution to the problem that arises when the TCP/IP protocol suite is used to provide Internet connectivity through mobile terminals over emerging 802.11 wireless links. Taking into consideration the strong drive towards ... More
Global Attitude Stabilization using Pseudo-TargetsNov 05 2018The topological obstructions on the attitude space of a rigid body make global asymptotic stabilization impossible using continuous state-feedback. This paper presents novel algorithms to overcome such topological limitations and achieve arbitrary attitude ... More
Quantum algorithms and approximating polynomials for composed functions with shared inputsSep 06 2018We give new quantum algorithms for evaluating composed functions whose inputs may be shared between bottom-level gates. Let $f$ be a Boolean function and consider a function $F$ obtained by applying $f$ to conjunctions of possibly overlapping subsets ... More
The Polynomial Method Strikes Back: Tight Quantum Query Bounds via Dual PolynomialsOct 25 2017May 25 2018The approximate degree of a Boolean function f is the least degree of a real polynomial that approximates f pointwise to error at most 1/3. Approximate degree is known to be a lower bound on quantum query complexity. We resolve or nearly resolve the approximate ... More
Improving Quantum Query Complexity of Boolean Matrix Multiplication Using Graph CollisionDec 26 2011Jan 23 2012The quantum query complexity of Boolean matrix multiplication is typically studied as a function of the matrix dimension, n, as well as the number of 1s in the output, \ell. We prove an upper bound of O (n\sqrt{\ell}) for all values of \ell. This is an ... More
The quantum query complexity of read-many formulasDec 02 2011The quantum query complexity of evaluating any read-once formula with n black-box input bits is Theta(sqrt(n)). However, the corresponding problem for read-many formulas (i.e., formulas in which the inputs have fanout) is not well understood. Although ... More
Systematic design methodology for development and flight testing of a variable pitch quadrotor biplane VTOL UAV for payload deliveryJan 07 2018This paper discusses the conceptual design and proof-of-concept flight demonstration of a novel variable pitch quadrotor biplane Unmanned Aerial Vehicle concept for payload delivery. The proposed design combines vertical takeoff and landing (VTOL), precise ... More
On the group theoretic structure of a class of quantum dialogue protocolsMar 27 2012Intrinsic symmetry of the existing protocols of quantum dialogue are explored. It is shown that if we have a set of mutually orthogonal $n$-qubit states {\normalsize $\{|\phi_{0}>,|\phi_{1}>,....,|\phi_{i}<,...,|\phi_{2^{n}-1}>\}$ and a set of $m-qubit$ ... More
Hamiltonian simulation with nearly optimal dependence on all parametersJan 08 2015Dec 07 2015We present an algorithm for sparse Hamiltonian simulation whose complexity is optimal (up to log factors) as a function of all parameters of interest. Previous algorithms had optimal or near-optimal scaling in some parameters at the cost of poor scaling ... More
Quantum Lower Bounds for Approximate Counting via Laurent PolynomialsApr 18 2019This paper proves new limitations on the power of quantum computers to solve approximate counting -- that is, multiplicatively estimating the size of a nonempty set $S\subseteq [N]$. Given only a membership oracle for $S$, it is well known that approximate ... More
Dipole Modulation of Cosmic Microwave Background Temperature and PolarizationJul 15 2015Oct 06 2015We propose a dipole modulation model for the Cosmic Microwave Background Radiation (CMBR) polarization field. We show that the model leads to correlations between l and l+1 multipoles, exactly as in the case of temperature. We obtain results for the case ... More
A Time-Efficient Quantum Walk for 3-Distinctness Using Nested UpdatesFeb 28 2013We present an extension to the quantum walk search framework that facilitates quantum walks with nested updates. We apply it to give a quantum walk algorithm for 3-Distinctness with query complexity ~O(n^{5/7}), matching the best known upper bound (obtained ... More
Quantum algorithm for simulating real time evolution of lattice HamiltoniansJan 11 2018Sep 28 2018We study the problem of simulating the time evolution of a lattice Hamiltonian, where the qubits are laid out on a lattice and the Hamiltonian only includes geometrically local interactions (i.e., a qubit may only interact with qubits in its vicinity). ... More
Birkhoff-von Neumann Graphs that are PM-compactJul 19 2018A geometric object of great interest in combinatorial optimization is the perfect matching polytope of a graph $G$. In any investigation concerning the perfect matching polytope, one may assume that $G$ is matching covered --- that is, it is a connected ... More
Random mesh projectors for inverse problemsMay 29 2018Dec 06 2018We propose a new learning-based approach to solve ill-posed inverse problems in imaging. We address the case where ground truth training samples are rare and the problem is severely ill-posed - both because of the underlying physics and because we can ... More
Easy and hard functions for the Boolean hidden shift problemApr 16 2013We study the quantum query complexity of the Boolean hidden shift problem. Given oracle access to f(x+s) for a known Boolean function f, the task is to determine the n-bit string s. The quantum query complexity of this problem depends strongly on f. We ... More
Minimal BracesMar 26 2019McCuaig (2001, Brace Generation, J. Graph Theory 38: 124-169) proved a generation theorem for braces, and used it as the principal induction tool to obtain a structural characterization of Pfaffian braces (2004, P{\'o}lya's Permanent Problem, Electronic ... More
Quantum linear systems algorithm with exponentially improved dependence on precisionNov 07 2015Harrow, Hassidim, and Lloyd showed that for a suitably specified $N \times N$ matrix $A$ and $N$-dimensional vector $\vec{b}$, there is a quantum algorithm that outputs a quantum state proportional to the solution of the linear system of equations $A\vec{x}=\vec{b}$. ... More
Security Toolbox for Detecting Novel and Sophisticated Android MalwareApr 07 2015This paper presents a demo of our Security Toolbox to detect novel malware in Android apps. This Toolbox is developed through our recent research project funded by the DARPA Automated Program Analysis for Cybersecurity (APAC) project. The adversarial ... More
Quantum algorithm for systems of linear equations with exponentially improved dependence on precisionNov 07 2015Sep 29 2017Harrow, Hassidim, and Lloyd showed that for a suitably specified $N \times N$ matrix $A$ and $N$-dimensional vector $\vec{b}$, there is a quantum algorithm that outputs a quantum state proportional to the solution of the linear system of equations $A\vec{x}=\vec{b}$. ... More
Dipole Modulation of Cosmic Microwave Background Temperature and PolarizationJul 15 2015Oct 29 2017We propose a dipole modulation model for the Cosmic Microwave Background Radiation (CMBR) polarization field. We show that the model leads to correlations between l and l+1 multipoles, exactly as in the case of temperature. We obtain results for the case ... More
Classical lower bounds from quantum upper boundsJul 17 2018We prove lower bounds on complexity measures, such as the approximate degree of a Boolean function and the approximate rank of a Boolean matrix, using quantum arguments. We prove these lower bounds using a quantum query algorithm for the combinatorial ... More
Imprint of Inhomogeneous and Anisotropic Primordial Power Spectrum on CMB PolarizationMar 31 2015We consider an inhomogeneous model and independently an anisotropic model of primordial power spectrum in order to describe the observed hemispherical anisotropy in Cosmic Microwave Background Radiation. This anisotropy can be parametrized in terms of ... More
Dipole anisotropy in sky brightness and source count distribution in radio NVSS dataJul 08 2013Jun 30 2014We study the dipole anisotropy in number counts and flux density weighted number counts {or sky brightness} in the NRAO VLA Sky Survey (NVSS) data. The dipole anisotropy is expected due to our local motion with respect to the CMBR rest frame. We analyse ... More
Trouble with the Drude theory of metallic conduction: Incompatibility with special relativityFeb 08 2016In this paper, we show that the classical Drude model of electrical conductivity, one of the fundamental models in the theory of electrical conductivity, is inconsistent with the special relativity. Due to this incorrect model, a current carrying closed ... More
Probing statistical isotropy of cosmological radio sources using SKAOct 26 2016There currently exist many observations which are not consistent with the cosmological principle. We review these observations with a particular emphasis on those relevant for Square Kilometre Array (SKA). In particular, several different data sets indicate ... More
YouTube-8M: A Large-Scale Video Classification BenchmarkSep 27 2016Many recent advancements in Computer Vision are attributed to large datasets. Open-source software packages for Machine Learning and inexpensive commodity hardware have reduced the barrier of entry for exploring novel approaches at scale. It is possible ... More
Simulating Hamiltonian dynamics with a truncated Taylor seriesDec 15 2014We describe a simple, efficient method for simulating Hamiltonian dynamics on a quantum computer by approximating the truncated Taylor series of the evolution operator. Our method can simulate the time evolution of a wide variety of physical systems. ... More
Impact of post deposition annealing in O2 ambient on structural properties of nanocrystalline hafnium oxide thin filmSep 03 2015May 04 2016In the present work, HfO2 thin film (100nm) has been deposited by sputtering technique and annealed at various temperatures ranging from 400 to 1000\degree (in step of 200 \degree) in O2 ambient for 10 min. The samples have been characterized using XRD, ... More
Imprint of Inhomogeneous and Anisotropic Primordial Power Spectrum on CMB PolarizationMar 31 2015Oct 29 2017We consider an inhomogeneous model and independently an anisotropic model of primordial power spectrum in order to describe the observed hemispherical anisotropy in Cosmic Microwave Background Radiation. This anisotropy can be parametrized in terms of ... More
Pose Embeddings: A Deep Architecture for Learning to Match Human PosesJul 01 2015We present a method for learning an embedding that places images of humans in similar poses nearby. This embedding can be used as a direct method of comparing images based on human pose, avoiding potential challenges of estimating body joint positions. ... More
Role of Spin, Phonon and Plasmon Dynamics on Ferromagnetism in Cr doped 3C-SiCOct 07 2018Nov 05 2018The defect induced magnetism has initiated a lot of interest in field of spintronics. In this regard, SiC is a promising material because of its unique properties under extreme conditions. Hence it will be very much interesting to investigate the interaction ... More
Utilizing Provenance in Reusable Research ObjectsJun 17 2018Science is conducted collaboratively, often requiring the sharing of knowledge about computational experiments. When experiments include only datasets, they can be shared using Uniform Resource Identifiers (URIs) or Digital Object Identifiers (DOIs). ... More
On essentially 4-edge-connected cubic bricksMar 23 2018Mar 18 2019Lov\'asz (1987) proved that every matching covered graph may be uniquely decomposed into a list of bricks (nonbipartite) and braces (bipartite). Carvalho, Lucchesi and Murty (2002) proved a conjecture of Lov\'asz which states that every brick $G$, distinct ... More
Resonant Transfer of Excitons and Quantum ComputationSep 11 2002Jan 06 2003Resonant energy transfer mechanisms have been observed in the sensitized luminescence of solids, in quantum dots and in molecular nanostructures, and they also play a central role in light harvesting processes in photosynthetic organisms. We demonstrate ... More
Exponential improvement in precision for simulating sparse HamiltoniansDec 05 2013Oct 07 2014We provide a quantum algorithm for simulating the dynamics of sparse Hamiltonians with complexity sublogarithmic in the inverse error, an exponential improvement over previous methods. Specifically, we show that a $d$-sparse Hamiltonian $H$ acting on ... More
Magnetic properties of iron nanoparticles prepared by exploding wire techniqueSep 15 2006Nanoparticles of iron were prepared in distilled water using very thin iron wires and sheets, by the electro-exploding wire technique. Transmission electron microscopy reveals the size of the nanoparticles to be in the range 10 to 50 nm. However, particles ... More
Separating quantum communication and approximate rankNov 17 2016One of the best lower bound methods for the quantum communication complexity of a function H (with or without shared entanglement) is the logarithm of the approximate rank of the communication matrix of H. This measure is essentially equivalent to the ... More
Blockchain and human episodic memoryNov 06 2018Jan 10 2019We relate the concepts used in decentralized ledger technology to studies of episodic memory in the mammalian brain. Specifically, we introduce the standard concepts of linked list, hash functions, and sharding, from computer science. We argue that these ... More
Separations in communication complexity using cheat sheets and information complexityMay 04 2016Aug 15 2016While exponential separations are known between quantum and randomized communication complexity for partial functions (Raz, STOC 1999), the best known separation between these measures for a total function is quadratic, witnessed by the disjointness function. ... More
Dissipation in circuit quantum electrodynamics: lasing and cooling of a low-frequency oscillatorJun 08 2008Superconducting qubits coupled to electric or nanomechanical resonators display effects previously studied in quantum electrodynamics (QED) and extensions thereof. Here we study a driven qubit coupled to a low-frequency tank circuit with particular emphasis ... More
Blockchain and human episodic memoryNov 06 2018Apr 16 2019We relate the concepts used in decentralized ledger technology to studies of episodic memory in the mammalian brain. Specifically, we introduce the standard concepts of linked list, hash functions, and sharding, from computer science. We argue that these ... More
Generating Simple Near-Bipartite BricksApr 28 2017Aug 11 2018A brick is a $3$-connected graph such that the graph obtained from it by deleting any two distinct vertices has a perfect matching. A brick $G$ is near-bipartite if it has a pair of edges $\alpha$ and $\beta$ such that $G-\{\alpha,\beta\}$ is bipartite ... More
Photogrammetric Measurements of a 12-metre Preloaded Parabolic Dish AntennaMay 08 2009May 10 2009A 12-metre Preloaded Parabolic Dish antenna, in which the backup structure is formed by preloading its radial and circumferential members, has been designed, built and commissioned by the Raman Research Institute, Bangalore. This paper reports the first-ever ... More
Artificial Neural Network based gamma-hadron segregation methodology for TACTIC telescopeJan 01 2013The sensitivity of a Cherenkov imaging telescope is strongly dependent on the rejection of the cosmic-ray background events. The methods which have been used to achieve the segregation between the gamma-rays from the source and the background cosmic-rays, ... More
Collaborative GAN SamplingFeb 02 2019Generative adversarial networks (GANs) have shown great promise in generating complex data such as images. A standard practice in GANs is to discard the discriminator after training and use only the generator for sampling. However, this loses valuable ... More
Simulation studies for optimizing the trigger generation criteria for the TACTIC telescopeMay 09 2011In this paper, we present the results of Monte Carlo simulations of $\gamma$-ray and cosmic ray proton induced extensive air showers as detected by the TACTIC atmospheric Cherenkov imaging telescope for optimizing its trigger field of view and topological ... More