Results for "J. Ignacio Cirac"

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Entanglement in many-body quantum systemsMay 16 2012Short review on entanglement, as seen from a quantum information perspective, and some simple applications to many-body quantum systems. Special emphasis in area laws, cold atoms, and efficient descriptions using tensor network states.
Number-resolving photon detectors with atoms coupled to waveguidesJun 28 2019Number-resolving single-photon detectors represent a key technology for a host of quantum optics protocols, comprising quantum state preparation, quantum metrology, entanglement distribution, and quantum computing. Despite significant advances over the ... More
Computational speedups using small quantum devicesJul 24 2018Jul 25 2018Suppose we have a small quantum computer with only M qubits. Can such a device genuinely speed up certain algorithms, even when the problem size is much larger than M? Here we answer this question to the affirmative. We present a hybrid quantum-classical ... More
Faster ground state preparation and high-precision ground energy estimation with fewer qubitsDec 08 2017Feb 02 2018We propose a general-purpose quantum algorithm for preparing ground states of quantum Hamiltonians from a given trial state. The algorithm is based on techniques recently developed in the context of solving the quantum linear systems problem [Childs,Kothari,Somma'15]. ... More
Variational Study of Fermionic and Bosonic Systems with Non-Gaussian States: Theory and ApplicationsJul 19 2017We present a new variational method for investigating the ground state and out of equilibrium dynamics of quantum many-body bosonic and fermionic systems. Our approach is based on constructing variational wavefunctions which extend Gaussian states by ... More
Rapid adiabatic preparation of injective PEPS and Gibbs statesAug 03 2015Mar 07 2016We propose a quantum algorithm for many-body state preparation. It is especially suited for injective PEPS and thermal states of local commuting Hamiltonians on a lattice. We show that for a uniform gap and sufficiently smooth paths, an adiabatic runtime ... More
A generalization of the injectivity condition for Projected Entangled Pair StatesJun 22 2017Dec 02 2018We introduce a family of tensor network states that we term semi-injective Projected Entangled-Pair States (PEPS). They extend the class of injective PEPS and include other states, like the ground states of the AKLT and the CZX models in square lattices. ... More
Classification of Matrix-Product Unitaries with SymmetriesDec 21 2018While the complete classification of symmetry-protected topological (SPT) matrix-product states is well established, that of matrix-product unitaries (MPUs) with symmetries stays an open problem. Here, we prove that MPUs with on-site unitary symmetries ... More
Digital lattice gauge theoriesJul 27 2016Feb 20 2017We propose a general scheme for a digital construction of lattice gauge theories with dynamical fermions. In this method, the four-body interactions arising in models with $2+1$ dimensions and higher, are obtained stroboscopically, through a sequence ... More
Digital quantum simulation of $\mathbb{Z}_2$ lattice gauge theories with dynamical fermionic matterJul 13 2016Feb 20 2017We propose a scheme for digital quantum simulation of lattice gauge theories with dynamical fermions. Using a layered optical lattice with ancilla atoms that can move and interact with the other atoms (simulating the physical degrees of freedom), we obtain ... More
Multi-photon Scattering Theory and Generalized Master EquationsJul 30 2015We develop a scattering theory to investigate the multi-photon transmission in a one-dimensional waveguide in the presence of quantum emitters. It is based on a path integral formalism, uses displacement transformations, and does not require the Markov ... More
Non-Abelian string breaking phenomena with Matrix Product StatesMay 17 2015Sep 03 2015Using matrix product states, we explore numerically the phenomenology of string breaking in a non-Abelian lattice gauge theory, namely 1+1 dimensional SU(2). The technique allows us to study the static potential between external heavy charges, as traditionally ... More
Variational Matrix Product Operators for the Steady State of Dissipative Quantum SystemsJan 27 2015Jun 09 2015We present a new variational method, based on the matrix product operator (MPO) ansatz, for finding the steady state of dissipative quantum chains governed by master equations of the Lindblad form. Instead of requiring an accurate representation of the ... More
Optomechanics assisted with a qubit: From dissipative state preparation to many-body physicsMay 29 2013We propose and analyze nonlinear optomechanical protocols that can be implemented by adding a single atom to an optomechanical cavity. In particular, we show how to engineer the environment in order to dissipatively prepare the mechanical oscillator in ... More
Ground States of Fermionic lattice Hamiltonians with Permutation SymmetryMay 20 2013Sep 23 2013We study the ground states of lattice Hamiltonians that are invariant under permutations, in the limit where the number of lattice sites, N -> \infty. For spin systems, these are product states, a fact that follows directly from the quantum de Finetti ... More
Resonating valence bond states in the PEPS formalismMar 21 2012Oct 19 2012We study resonating valence bond (RVB) states in the Projected Entangled Pair States (PEPS) formalism. Based on symmetries in the PEPS description, we establish relations between the toric code state, the orthogonal dimer state, and the SU(2) singlet ... More
Dissipative Long-Range Entanglement Generation between Electronic SpinsMar 03 2016Aug 18 2016We propose a scheme for deterministic generation and long-term stabilization of entanglement between two electronic spin qubits confined in spatially separated quantum dots. Our approach relies on an electronic quantum bus, consisting either of quantum ... More
Quantum Gross-Pitaevskii EquationJan 26 2015May 15 2017We introduce a non-commutative generalization of the Gross-Pitaevskii equation for one-dimensional quantum gasses and quantum liquids. This generalization is obtained by applying the time-dependent variational principle to the variational manifold of ... More
Long-Distance Transfer and Routing of Static Magnetic FieldsApr 23 2013Sep 02 2014We show how the static magnetic field of a finite source can be transferred and routed to arbitrary long distances. This is achieved by using transformation optics, which results in a device made of a material with a highly anisotropic magnetic permeability. ... More
Quantum Correlations in Two-Fermion SystemsDec 18 2000Apr 20 2001We characterize and classify quantum correlations in two-fermion systems having 2K single-particle states. For pure states we introduce the Slater decomposition and rank (in analogy to Schmidt decomposition and rank), i.e. we decompose the state into ... More
Density Induced Phase Transitions in the Schwinger Model: A Study with Matrix Product StatesNov 02 2016Feb 20 2017We numerically study the zero temperature phase structure of the multiflavor Schwinger model at nonzero chemical potential. Using matrix product states, we reproduce analytical results for the phase structure for two flavors in the massless case and extend ... More
Lattice effects on Laughlin wave functions and parent HamiltoniansSep 08 2016Dec 02 2016We investigate lattice effects on wave functions that are lattice analogues of bosonic and fermionic Laughlin wave functions with number of particles per flux $\nu=1/q$ in the Landau levels. These wave functions are defined analytically on lattices with ... More
Quantum dynamics of propagating photons with strong interactions: a generalized input-output formalismJan 19 2015There has been rapid development of systems that yield strong interactions between freely propagating photons in one dimension via controlled coupling to quantum emitters. This raises interesting possibilities such as quantum information processing with ... More
Purifications of multipartite states: limitations and constructive methodsAug 08 2013Dec 20 2013We analyze the description of quantum many-body mixed states using matrix product states and operators. We consider two such descriptions: (i) as a matrix product density operator of bond dimension D, and (ii) as a purification that is written as a matrix ... More
Symmetries and boundary theories for chiral Projected Entangled Pair StatesMay 02 2014Aug 25 2014We investigate the topological character of lattice chiral Gaussian fermionic states in two dimensions possessing the simplest descriptions in terms of projected entangled-pair states (PEPS). They are ground states of two different kinds of Hamiltonians. ... More
Dissipative Phase Transition in Central Spin SystemsMay 15 2012May 16 2012We investigate dissipative phase transitions in an open central spin system. In our model the central spin interacts coherently with the surrounding many-particle spin environment and is subject to coherent driving and dissipation. We develop analytical ... More
Adiabatic Preparation of a Heisenberg Antiferromagnet Using an Optical SuperlatticeJun 08 2011Nov 06 2011We analyze the possibility to prepare a Heisenberg antiferromagnet with cold fermions in optical lattices, starting from a band insulator and adiabatically changing the lattice potential. The numerical simulation of the dynamics in 1D allows us to identify ... More
Unforgeable Noise-Tolerant Quantum TokensDec 22 2011The realization of devices which harness the laws of quantum mechanics represents an exciting challenge at the interface of modern technology and fundamental science. An exemplary paragon of the power of such quantum primitives is the concept of "quantum ... More
Quantum Rydberg Central Spin ModelMay 21 2019Jun 18 2019We consider dynamics of a Rydberg impurity in a cloud of ultracold bosonic atoms in which the Rydberg electron can undergo spin-changing collisions with surrounding atoms. This system realizes a new type of the quantum impurity problem that compounds ... More
Expressive power of tensor-network factorizations for probabilistic modeling, with applications from hidden Markov models to quantum machine learningJul 08 2019Tensor-network techniques have enjoyed outstanding success in physics, and have recently attracted attention in machine learning, both as a tool for the formulation of new learning algorithms and for enhancing the mathematical understanding of existing ... More
Tensor Networks and their use for Lattice Gauge TheoriesOct 30 2018Nov 06 2018Tensor Network States are ans\"atze for the efficient description of quantum many-body systems. Their success for one dimensional problems, together with the fact that they do not suffer from the sign problem and can address the simulation of real time ... More
Solid-state magnetic traps and latticesApr 20 2018Jul 02 2018We propose and analyze magnetic traps and lattices for electrons in semiconductors. We provide a general theoretical framework and show that thermally stable traps can be generated by magnetically driving the particle's internal spin transition, akin ... More
Adiabatic Time Evolution in Spin-SystemsSep 02 2003Adiabatic processes in the quantum Ising model and the anisotropic Heisenberg model are discussed. The adiabatic processes are assumed to consist in the slow variation of the strength of the magnetic field that environs the spin-systems. These processes ... More
Cold atoms in twisted bilayer optical potentialsJul 13 2019The possibility of creating crystal bilayers twisted with respect to each other has led to the discovery of a wide range of novel electron correlated phenomena whose full understanding is still under debate. Here we propose and analyze a method to simulate ... More
Engineering correlation and entanglement dynamics in spin systemsJan 10 2007We show that the correlation and entanglement dynamics of spin systems can be understood in terms of propagation of spin waves. This gives a simple, physical explanation of the behaviour seen in a number of recent works, in which a localised, low-energy ... More
A magnetic tomography of a cavity stateAug 19 1996Aug 22 1996A method to determine the state of a single quantized cavity mode is proposed. By adiabatic passage, the quantum state of the field is transfered completely onto an internal Zeeman sub-manifold of an atom. Utilizing a method of Newton and Young, we can ... More
Removing Staggered Fermionic Matter in $U(N)$ and $SU(N)$ Lattice Gauge TheoriesMay 02 2019Gauge theories, through the local symmetry which is in their core, exhibit many local constraints, that must be taken care of and addressed in any calculation. In the Hamiltonian picture this is phrased through the Gauss laws, local constraints that restrict ... More
Time-dependent study of disordered models with infinite projected entangled pair statesDec 10 2018Feb 14 2019Infinite projected entangled pair states (iPEPS), the tensor network ansatz for two-dimensional systems in the thermodynamic limit, already provide excellent results on ground-state quantities using either imaginary-time evolution or variational optimisation. ... More
Quantum emulsion: a glassy phase of bosonic mixtures in optical latticesDec 04 2006We numerically investigate mixtures of two interacting bosonic species with unequal parameters in one-dimensional optical lattices. In large parameter regions full phase segregation is seen to minimize the energy of the system, but the true ground state ... More
Matrix Product State and mean field solutions for one-dimensional systems can be found efficientlyOct 22 2009Jul 19 2010We consider the problem of approximating ground states of one-dimensional quantum systems within the two most common variational ansatzes, namely the mean field ansatz and Matrix Product States. We show that both for mean field and for Matrix Product ... More
A de Finetti representation theorem for infinite dimensional quantum systems and applications to quantum cryptographySep 12 2008According to the quantum de Finetti theorem, if the state of an N-partite system is invariant under permutations of the subsystems then it can be approximated by a state where almost all subsystems are identical copies of each other, provided N is sufficiently ... More
Ground-state properties of the spin-1/2 antiferromagnetic Heisenberg model on the triangular lattice: A variational study based on entangled-plaquette statesJun 23 2010Oct 27 2010We study, on the basis of the general entangled-plaquette variational ansatz, the ground-state properties of the spin-1/2 antiferromagnetic Heisenberg model on the triangular lattice. Our numerical estimates are in good agreement with available exact ... More
Infinite matrix product states, Conformal Field Theory and the Haldane-Shastry modelNov 16 2009Nov 26 2009We generalize the Matrix Product States method using the chiral vertex operators of Conformal Field Theory and apply it to study the ground states of the XXZ spin chain, the J1-J2 model and random Heisenberg models. We compute the overlap with the exact ... More
Continuous Tensor Network States for Quantum FieldsAug 02 2018We introduce a new class of states for bosonic quantum fields which extend tensor network states to the continuum and generalize continuous matrix product states (cMPS) to spatial dimensions $d\geq 2$. By construction, they are Euclidean invariant, and ... More
Eliminating fermionic matter fields in lattice gauge theoriesMay 14 2018Aug 16 2018We devise a unitary transformation that replaces the fermionic degrees of freedom of lattice gauge theories by (hard-core) bosonic ones. The resulting theory is local and gauge invariant, with the same symmetry group. The method works in any spatial dimensions ... More
Discrete entanglement distribution with squeezed lightJul 22 2003We show how one can entangle distant atoms by using squeezed light. Entanglement is obtained in steady state, and can be increased by manipulating the atoms locally. We study the effects of imperfections, and show how to scale up the scheme to build a ... More
The characterization of Gaussian operations and Distillation of Gaussian StatesApr 16 2002Oct 15 2002We characterize the class of all physical operations that transform Gaussian states to Gaussian states. We show that this class coincides with that of all operations which can be performed on Gaussian states using linear optical elements and homodyne ... More
Continuous Tensor Network States for Quantum FieldsAug 02 2018Jun 08 2019We introduce a new class of states for bosonic quantum fields which extend tensor network states to the continuum and generalize continuous matrix product states (cMPS) to spatial dimensions $d\geq 2$. By construction, they are Euclidean invariant, and ... More
Combining Tensor Networks with Monte Carlo Methods for Lattice Gauge TheoriesOct 30 2017Feb 26 2018Gauged gaussian Projected Entangled Pair States are particular tensor network constructions that describe lattice states of fermionic matter interacting with dynamical gauge fields. We show how one can efficiently compute, using Monte-Carlo techniques, ... More
Quantum repeaters for communicationMar 20 1998In quantum communication via noisy channels, the error probability scales exponentially with the length of the channel. We present a scheme of a quantum repeater that overcomes this limitation. The central idea is to connect a string of (imperfect) entangled ... More
Quantum repeaters based on entanglement purificationAug 31 1998We study the use of entanglement purification for quantum communication over long distances. For distances much longer than the coherence length of a corresponding noisy quantum channel, the fidelity of transmission is usually so low that standard purification ... More
The mass spectrum of the Schwinger model with Matrix Product StatesMay 16 2013Nov 10 2013We show the feasibility of tensor network solutions for lattice gauge theories in Hamiltonian formulation by applying matrix product states algorithms to the Schwinger model with zero and non-vanishing fermion mass. We introduce new techniques to compute ... More
Extended Rindler Spacetime and a New Multiverse StructureDec 04 2017Mar 19 2018This is the first of a series of papers in which we use analyticity properties of quantum fields propagating on a spacetime to uncover a new multiverse geometry when the classical geometry has horizons and/or singularities. The nature and origin of the ... More
A quantum interface between light and nuclear spins in quantum dotsOct 24 2008Jan 18 2010The coherent coupling of flying photonic qubits to stationary matter-based qubits is an essential building block for quantum communication networks. We show how such a quantum interface can be realized between a traveling-wave optical field and the polarized ... More
On the effective size of certain "Schrödinger cat'' like statesMay 16 2002Several experiments and experimental proposals for the production of macroscopic superpositions naturally lead to states of the general form $|\phi_1>^{\otimes N}+|\phi_2>^{\otimes N}$, where the number of subsystems $N$ is very large, but the states ... More
Bound entanglement for continuous variables is a rare phenomenonMar 14 2001Oct 18 2001We discuss the notion of bound entanglement (BE) for continuous variables (CV). We show that the set of non--distillable states (NDS) for CV is nowhere dense in the set of all states, i.e., the states of infinite--dimensional bipartite systems are generically ... More
Chiral topological spin liquids with projected entangled pair statesApr 20 2015Jul 08 2015Topological chiral phases are ubiquitous in the physics of the Fractional Quantum Hall Effect. Non-chiral topological spin liquids are also well known. Here, using the framework of projected entangled pair states (PEPS), we construct a family of chiral ... More
Dissipative Dynamics and Phase Transitions in Fermionic SystemsJul 06 2012Feb 15 2013We study abrupt changes in the dynamics and/or steady state of fermionic dissipative systems produced by small changes of the system parameters. Specifically, we consider open fermionic systems whose dynamics is described by master equations that are ... More
Quantum entanglement theory in the presence of superselection rulesApr 13 2004Superselection rules severly constrain the operations which can be implemented on a distributed quantum system. While the restriction to local operations and classical communication gives rise to entanglement as a nonlocal resource, particle number conservation ... More
Interfacing nuclear spins in quantum dots to cavity or traveling-wave fieldsMar 10 2009Nov 19 2009We show how to realize a quantum interface between optical fields and the polarized nuclear spins in a singly charged quantum dot, which is strongly coupled to a high-finesse optical cavity. An effective direct coupling between cavity and nuclear spins ... More
Projected Entangled Pair States with continuous virtual symmetriesMay 09 2018We study Projected Entangled Pair States (PEPS) with continuous virtual symmetries, i.e., symmetries in the virtual degrees of freedom, through an elementary class of models with SU(2) symmetry. Discrete symmetries of that kind have previously allowed ... More
Dissipative spin chains: Implementation with cold atoms and steady-state propertiesJul 24 2012Feb 15 2013We propose a quantum optical implementation of a class of dissipative spin systems, including the XXZ and Ising model, with ultra-cold atoms in optical lattices. Employing the motional degree of freedom of the atoms and detuned Raman transitions we show ... More
Quantum simulations of gauge theories with ultracold atoms: local gauge invariance from angular momentum conservationMar 20 2013Aug 28 2013Quantum simulations of High Energy Physics, and especially of gauge theories, is an emerging and exciting direction in quantum simulations. However, simulations of such theories, compared to simulations of condensed matter physics, must satisfy extra ... More
Simulating Compact Quantum Electrodynamics with ultracold atoms: Probing confinement and nonperturbative effectsApr 30 2012Sep 20 2012Recently, there has been much interest in simulating quantum field theory effects of matter and gauge fields. In a recent work [Phys. Rev. Lett. 107, 275301 (2011)] a method for simulating compact Quantum Electrodynamics (cQED) using Bose-Einstein condensates ... More
Teleportation and spin squeezing utilizing multimode entanglement of light with atomsNov 17 2005We present a protocol for the teleportation of the quantum state of a pulse of light onto the collective spin state of an atomic ensemble. The entangled state of light and atoms employed as a resource in this protocol is created by probing the collective ... More
Entanglement flow in multipartite systemsApr 30 2004Sep 14 2004We investigate entanglement dynamics in multipartite systems, establishing a quantitative concept of entanglement flow: both flow through individual particles, and flow along general networks of interacting particles. In the former case, the rate at which ... More
Entanglement Percolation in Quantum NetworksDec 19 2006Quantum networks are composed of nodes which can send and receive quantum states by exchanging photons. Their goal is to facilitate quantum communication between any nodes, something which can be used to send secret messages in a secure way, and to communicate ... More
Dynamical creation of a supersolid in asymmetric mixtures of bosonsJun 05 2009We propose a scheme to dynamically create a supersolid state in an optical lattice, using an attractive mixture of mass-imbalanced bosons. Starting from a "molecular" quantum crystal, supersolidity is induced dynamically as an out-of-equilibrium state. ... More
Generalized Hartree-Fock Theory for Interacting Fermions in Lattices: Numerical MethodsMay 28 2010Sep 28 2010We present numerical methods to solve the Generalized Hartree-Fock theory for fermionic systems in lattices, both in thermal equilibrium and out of equilibrium. Specifically, we show how to determine the covariance matrix corresponding to the Fermionic ... More
Field-induced superfluids and Bose liquids in Projected Entangled Pair StatesAug 15 2013Oct 05 2013In two-dimensional incompressible quantum spin liquids, a large enough magnetic field generically induces "doping" of polarized S=1 triplons or S=1/2 spinons. We review a number of cases such as spin-3/2 AKLT or spin-1/2 Resonating Valence Bond (RVB) ... More
A cold-atom quantum simulator for SU(2) Yang-Mills lattice gauge theoryNov 09 2012Nov 15 2012Non-abelian gauge theories play an important role in the standard model of particle physics, and unfold a partially unexplored world of exciting physical phenomena. In this letter, we suggest a realization of a non-abelian lattice gauge theory - SU(2) ... More
Supervised learning with generalized tensor networksJun 15 2018Tensor networks have found a wide use in a variety of applications in physics and computer science, recently leading to both theoretical insights as well as practical algorithms in machine learning. In this work we explore the connection between tensor ... More
Dividing Quantum ChannelsNov 22 2006Mar 10 2008We investigate the possibility of dividing quantum channels into concatenations of other channels, thereby studying the semigroup structure of the set of completely-positive trace-preserving maps. We show the existence of 'indivisible' channels which ... More
Quantum Simulations of Lattice Gauge Theories using Ultracold Atoms in Optical LatticesMar 08 2015Dec 25 2015Can high energy physics be simulated by low-energy, non-relativistic, many-body systems, such as ultracold atoms? Such ultracold atomic systems lack the type of symmetries and dynamical properties of high energy physics models: in particular, they manifest ... More
Simulating 2+1d Lattice QED with dynamical matter using ultracold atomsAug 21 2012Sep 07 2012We suggest a method to simulate lattice compact Quantum Electrodynamics (cQED) using ultracold atoms in optical lattices, which includes dynamical Dirac fermions in 2+1 dimensions. This allows to test dynamical effects of confinement as well as 2d flux ... More
Ultrafast molecular dynamics in terahertz-STM experiments: Theoretical analysis using Anderson-Holstein modelApr 01 2019We analyze ultrafast tunneling experiments in which electron transport through a localized orbital is induced by a single cycle THz pulse. We include both electron-electron and electron-phonon interactions on the localized orbital using the Anderson-Holstein ... More
Spin monopoles with Bose-Einstein condenstatesNov 24 1998We study the feasibility of preparing a Bose-Einstein condensed sample of atoms in a 2D spin monopole. In this state, the atomic internal spins lie in the x-y plane, and point in the radial direction.
Motion Tomography of a single trapped ionJan 08 1996Jan 16 1996A method for the experimental reconstruction of the quantum state of motion for a single trapped ion is proposed. It is based on the measurement of the ground state population of the trap after a sudden change of the trapping potential. In particular, ... More
Entropically-induced asymmetric passage times of charged tracers across corrugated channelsJan 18 2016We analyze the diffusion of charged and neutral tracers suspended in an electrolyte embedded in a channel of varying cross-section. Making use of systematic approximations, the diffusion equation governing the motion of tracers is mapped into an effective ... More
Reduced form of a Mueller matrixSep 22 2015Mar 12 2016Through a simple procedure based on the Lu-Chipman decomposition [S-Y. Lu and R. C. Chipman, J. Opt. Soc. Am A 13, 1106 (1996)] any depolarizing Mueller matrix can be transformed into a reduced form which accumulates the depolarization and polarizance ... More
Invariant quantities of a nondepolarizing Mueller matrixApr 05 2016Jun 03 2016Orthogonal Mueller matrices can be considered either as corresponding to retarders or to generalized transformations of the polarization basis for the representation of Stokes vectors, so that they constitute the only type of Mueller matrices that preserve ... More
Journey Beyond the Schwarzschild Black Hole SingularityOct 12 2015We present the geodesical completion of the Schwarzschild black hole in four dimensions which covers the entire space in (u,v) Kruskal-Szekeres coordinates, including the spacetime behind the black and white hole singularities. The gravitational constant ... More
Confined Brownian ratchetsMay 22 2013We analyze the dynamics of Brownian ratchets in a confined environment. The motion of the particles is described by a Fick-Jakobs kinetic equation in which the presence of boundaries is modeled by means of an entropic potential. The cases of a flashing ... More
Dark Matter annihilation energy output and its effects on the high-z IGMFeb 22 2013Aug 29 2014We study the case of DM self annihilation, in order to assess its importance as an energy injection mechanism, to the IGM in general, and to the medium within particular DM haloes. We consider thermal relic WIMP particles with masses of 10GeV and 1TeV ... More
Topological terms, AdS_2n gravity and renormalized Entanglement Entropy of holographic CFTsMar 13 2018We extend our topological renormalization scheme for Entanglement Entropy to holographic CFTs of arbitrary odd dimensions in the context of the AdS/CFT correspondence. The procedure consists in adding the Chern form as a boundary term to the area functional ... More
qNoise: A generator of non-Gaussian colored noiseNov 28 2018We introduce a software generator for a class of \emph{colored} (self-correlated) and \emph{non-Gaussian} noise, whose statistics and spectrum depend upon only two parameters, $q$ and $\tau$. Inspired by Tsallis' nonextensive formulation of statistical ... More
Distinguishing the effects of internal and forced atmospheric variability in climate networksNov 13 2013The fact that the Earth climate is a highly complex dynamical system is well-known. In the last few decades a lot of effort has been focused on understanding how climate phenomena in one geographical region affects the climate of other regions. Complex ... More
Assessing the direction of climate interactions by means of complex networks and information theoretic toolsFeb 04 2015An estimate of the net direction of climate interactions in different geographical regions is made by constructing a directed climate network from a regular latitude-longitude grid of nodes, using a directionality index (DI) based on conditional mutual ... More
Sonic analog of gravitational black holes in Bose-Einstein condensatesFeb 03 2000Dec 04 2000It is shown that, in dilute-gas Bose-Einstein condensates, there exist both dynamically stable and unstable configurations which, in the hydrodynamic limit, exhibit a behavior resembling that of gravitational black holes. The dynamical instabilities involve ... More
Sonic black holes in dilute Bose-Einstein condensatesMay 31 2000Jan 18 2001The sonic analog of a gravitational black hole in dilute-gas Bose-Einstein condensates is investigated. It is shown that there exist both dynamically stable and unstable configurations which, in the hydrodynamic limit, exhibit a behavior completely analogous ... More
Simulating two- and three-dimensional frustrated quantum systems with string-bond statesAug 27 2009Jul 07 2010Simulating frustrated quantum magnets is among the most challenging tasks in computational physics. We apply String-Bond States, a recently introduced ansatz which combines Tensor Networks with Monte Carlo based methods, to the simulation of frustrated ... More
Digital quantum simulation of $\mathbb{Z}_2$ lattice gauge theories with dynamical fermionic matterJul 13 2016We propose a scheme for digital quantum simulation of lattice gauge theories with dynamical fermions. Using a layered optical lattice with ancilla atoms that can move and interact with the other atoms (simulating the physical degrees of freedom), we obtain ... More
The computational complexity of PEPSNov 06 2006Apr 13 2007We determine the computational power of preparing Projected Entangled Pair States (PEPS), as well as the complexity of classically simulating them, and generally the complexity of contracting tensor networks. While creating PEPS allows to solve PP problems, ... More
Quantum simulation of the Schwinger model: A study of feasibilityJul 18 2014Dec 10 2014We analyze some crucial questions regarding the practical feasibility of quantum simulation for lattice gauge models. Our analysis focuses on two models suitable for the quantum simulation of the Schwinger Hamiltonian, or QED in 1+1 dimensions, which ... More
Laughlin spin liquid states on lattices obtained from conformal field theoryJan 15 2012May 28 2012We propose a set of spin system wavefunctions that are very similar to lattice versions of the Laughlin states. The wavefunction are conformal blocks of conformal field theories, and for filling factor \nu=1/2 we provide a parent Hamiltonian, which is ... More
Mathematical open problems in Projected Entangled Pair StatesMar 22 2019Projected Entangled Pair States (PEPS) are used in practice as an efficient parametrization of the set of ground states of quantum many body systems. The aim of this paper is to present, for a broad mathematical audience, some mathematical questions about ... More
Correlation decay in fermionic lattice systems with power-law interactions at non-zero temperatureFeb 01 2017Mar 23 2017We study correlations in fermionic lattice systems with long-range interactions in thermal equilibrium. We prove a bound on the correlation decay between anti-commuting operators and generalize a long-range Lieb-Robinson type bound. Our results show that ... More
Digital lattice gauge theoriesJul 27 2016We propose a general scheme for a digital construction of lattice gauge theories with dynamical fermions. In this method, the four-body interactions arising in models with $2+1$ dimensions and higher, are obtained stroboscopically, through a sequence ... More
Strings, Projected Entangled Pair States, and variational Monte Carlo methodsAug 12 2007Apr 04 2008We introduce string-bond states, a class of states obtained by placing strings of operators on a lattice, which encompasses the relevant states in Quantum Information. For string-bond states, expectation values of local observables can be computed efficiently ... More
Hawking Radiation from an Acoustic Black Hole on an Ion RingApr 30 2009Jun 24 2010In this article we propose to simulate acoustic black holes with ions in rings. If the ions are rotating with a stationary and inhomogeneous velocity profile, regions can appear where the ion velocity exceeds the group velocity of the phonons. In these ... More