Infinite matrix product states, Conformal Field Theory and the Haldane-Shastry model (2009)
Cirac, J. Ignacio, Sierra, German
We 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...
Schuch, Norbert, Cirac, J. Ignacio
We prove that the best approximation to ground states of one-dimensional quantum systems within the two most common variational ansatzes, namely the mean field ansatz and Matrix Product States, can...
Towards Quantum Superposition of Living Organisms (2009)
Romero-Isart, Oriol, Juan, Mathieu L., Quidant, Romain, Cirac, J. Ignacio
The most striking feature of quantum mechanics is the existence of superposition states, where an object appears to be in different situations at the same time. The existence of such states has been...
Simulating two- and three-dimensional frustrated quantum systems with string-bond states (2009)
Sfondrini, Alessandro, Cerrillo, Javier, Schuch, Norbert, Cirac, J. Ignacio
Simulating 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...
Dynamical creation of a supersolid in asymmetric mixtures of bosons (2009)
Keilmann, Tassilo, Cirac, J. Ignacio, Roscilde, Tommaso
We 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...
Mezzacapo, Fabio, Schuch, Norbert, Boninsegni, Massimo, Cirac, J. Ignacio
We propose a new ansatz for the ground-state wave function of quantum many-body systems on a lattice. The key idea is to cover the lattice with plaquettes and obtain a state whose configurational...
Fermionic Projected Entangled Pair States (2009)
Kraus, Christina V., Schuch, Norbert, Verstraete, Frank, Cirac, J. Ignacio
We introduce a family of states, the fPEPS, which describes fermionic systems on lattices in arbitrary spatial dimensions. It constitutes the natural extension of another family of states, the PEPS,...
Interfacing nuclear spins in quantum dots to cavity or traveling-wave fields (2009)
Schwager, Heike, Cirac, J. Ignacio, Giedke, Geza
We 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...
Dissipation-induced hard-core boson gas in an optical lattice (2009)
García-Ripoll, Juan José, Dürr, Stephan, Syassen, Niels, Bauer, Dominik M., Lettner, Matthias, Rempe, Gerhard, ...
Pairing in fermionic systems: A quantum-information perspective (2009)
Kraus, Christina V., Wolf, Michael M., Cirac, J. Ignacio, Giedke, Géza
Lieb-Liniger model of a dissipation-induced Tonks-Girardeau gas (2009)
Dürr, Stephan, Garcia-Ripoll, Juan José, Syassen, Niels, Bauer, Dominik M., Lettner, Matthias, Cirac, J. Ignacio, ...
Matrix product states: Symmetries and two-body Hamiltonians (2009)
Sanz, Mikel, Wolf, Michael M., Perez-García, David, Cirac, J. Ignacio
Matrix Product States for Dynamical Simulation of Infinite Chains (2009)
Bañuls, Mari Carmen, Hastings, M. B., Verstraete, F., Cirac, J. Ignacio
How Long Can a Quantum Memory Withstand Depolarizing Noise? (2009)
Pastawski, Fernando, Kay, Alastair, Schuch, Norbert, Cirac, J. Ignacio
Pairing in fermionic systems: A quantum information perspective (2008)
Kraus, Christina V., Wolf, Michael M., Cirac, J. Ignacio, Giedke, Geza
The notion of "paired" fermions is central to important condensed matter phenomena such as superconductivity and superfluidity. While the concept is widely used and its physical meaning is clear...
A quantum interface between light and nuclear spins in quantum dots (2008)
Schwager, Heike, Cirac, J. Ignacio, Giedke, Géza
The 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...
Renner, Renato, Cirac, J. Ignacio
According 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...
Matter--wave emission in optical lattices: Single particle and collective effects (2008)
De Vega, Ines, Porras, Diego, Cirac, J. Ignacio
We introduce a simple set--up corresponding to the matter-wave analogue of impurity atoms embedded in an infinite photonic crystal and interacting with the radiation field. Atoms in a given internal...
Detecting entanglement in two mode squeezed states by particle counting (2008)
Muschik, Christine A., Polzik, Eugene S., Cirac, J. Ignacio
We present an entanglement criterion for two mode squeezed states which relies on particle counting only. The proposed inequality is optimal for the state under consideration and robust against...
Quantum circuits for strongly correlated quantum systems (2008)
Verstraete, Frank, Cirac, J. Ignacio, Latorre, Jose I.
In recent years, we have witnessed an explosion of experimental tools by which quantum systems can be manipulated in a controlled and coherent way. One of the most important goals now is to build...
Verstraete, Frank, Wolf, Michael M., Cirac, J. Ignacio
We investigate the computational power of creating steady-states of quantum dissipative systems whose evolution is governed by time-independent and local couplings to a memoryless environment. We...
Sequentially generated states for the study of two dimensional systems (2008)
Bañuls, Mari-Carmen, Pérez-García, David, Wolf, Michael M., Verstraete, Frank, Cirac, J. Ignacio
Matrix Product States can be defined as the family of quantum states that can be sequentially generated in a one-dimensional system. We introduce a new family of states which extends this definition...
On entropy growth and the hardness of simulating time evolution (2008)
Schuch, Norbert, Wolf, Michael M., Vollbrecht, Karl Gerd H., Cirac, J. Ignacio
The simulation of quantum systems is a task for which quantum computers are believed to give an exponential speedup as compared to classical ones. While ground states of one-dimensional systems can...
Entropy Scaling and Simulability by Matrix Product States (2008)
Schuch, Norbert, Wolf, Michael M., Verstraete, Frank, Cirac, J. Ignacio
Area Laws in Quantum Systems: Mutual Information and Correlations (2008)
Wolf, Michael M., Verstraete, Frank, Hastings, Matthew B., Cirac, J. Ignacio
Entanglement distribution in pure-state quantum networks (2008)
Perseguers, Sébastien, Cirac, J. Ignacio, Acin, A., Lewenstein, M., Wehr, J.
On entropy growth and the hardness of simulating time evolution (2008)
Schuch, Norbert, Wolf, Michael M., Vollbrecht, Karl G. H., Cirac, J. Ignacio
String order and symmetries in quantum spin lattices (2008)
Pérez-García, David, Wolf, Michael M., Sanz Riuz, Mikel, Verstraete, Frank, Cirac, J. Ignacio
Quantum phases of trapped ions in an optical lattice (2008)
Schmied, Roland, Roscilde, Tommasso, Murg, Valentin, Porras, Diego, Cirac, J. Ignacio
Strong Dissipation Inhibits Losses and Induces Correlations in Cold Molecular Gases (2008)
Syassen, Nils, Bauer, Dominik M., Lettner, Matthias, Volz, Thomas, Dietze, Daniel, Garcia-Ripoll, Juan J., ...
Sequentially generated states for the study of two-dimensional systems (2008)
Bañuls, Mari Carmen, Pérez-García, David, Wolf, Michael M., Verstraete, Frank, Cirac, J. Ignacio
Computational difficulty of finding matrix product ground states (2008)
Schuch, Norbert, Cirac, J. Ignacio, Verstraete, Frank
We determine the computational difficulty of finding ground states of one-dimensional (1D) Hamiltonians, which are known to be matrix product states (MPS). To this end, we construct a class of 1D...
Mesoscopic spin-boson models of trapped ions (2008)
Porras, Diego, Marquardt, F., Von Delft, J., Cirac, J. Ignacio
Quantum Processing Photonic States in Optical Lattices (2008)
Muschik, Christine A., De Vega, Inés, Porras, Diego, Cirac, J. Ignacio
PEPS as unique ground states of local Hamiltonians (2008)
Perez-García, David, Verstraete, Frank, Wolf, Michael M., Cirac, J. Ignacio
Assessing Non-Markovian Quantum Dynamics (2008)
Wolf, Michael M., Eisert, J., Cubitt, T. S., Cirac, J. Ignacio
Classical Simulation of Infinite-Size Quantum Lattice Systems in Two Spatial Dimensions (2008)
Jordan, J., Orus, R., Vidal, G., Verstraete, F., Cirac, J. Ignacio
Creation, Manipulation, and Detection of Abelian and Non-Abelian Anyons in Optical Lattices (2008)
Aguado, Miguel, Brennen, G. K., Verstraete, F., Cirac, J. Ignacio
One-shot entanglement generation over long distances in noisy quantum networks (2008)
Perseguers, Sébastien, Jiang, L., Schuch, Norbert, Verstraete, F., Lukin, M. D., Cirac, J. Ignacio, ...
Quantum Phases of Trapped Ions in an Optical Lattice (2007)
Schmied, Roman, Roscilde, Tommaso, Murg, Valentin, Porras, Diego, Cirac, J. Ignacio
We propose loading trapped ions into microtraps formed by an optical lattice. For harmonic microtraps, the Coulomb coupling of the spatial motions of neighboring ions can be used to construct a broad...
Collective Laser Cooling of Trapped Atoms (2007)
J. Ignacio Cirac, Maciej Lewenstein, Peter Zoller
We show that by a suciently slow repumping process, one can avoid the problems of reabsorptions in laser cooling of trapped atoms, even in the case of optically thick samples. 03.75Fi,...
Strings, Projected Entangled Pair States, and variational Monte Carlo methods (2007)
Schuch, Norbert, Wolf, Michael M., Verstraete, Frank, Cirac, J. Ignacio
We 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,...
PEPS as unique ground states of local Hamiltonians (2007)
Perez-Garcia, David, Verstraete, Frank, Cirac, J. Ignacio, Wolf, Michael M.
In this paper we consider projected entangled pair states (PEPS) on arbitrary lattices. We construct local parent Hamiltonians for each PEPS and isolate a condition under which the state is the...
Entropy scaling and simulability by Matrix Product States (2007)
Schuch, Norbert, Wolf, Michael M., Verstraete, Frank, Cirac, J. Ignacio
We investigate the relation between the scaling of block entropies and the efficient simulability by Matrix Product States (MPS), and clarify the connection both for von Neumann and Renyi entropies...
Sequential generation of matrix-product states in cavity QED (2007)
Schön, C., Hammerer, K., Wolf, Michael M., Cirac, J. Ignacio, Solano, E.
Computational Complexity of Projected Entangled Pair States (2007)
Schuch, Norbert, Wolf, Michael M., Verstraete, Frank, Cirac, J. Ignacio
Matrix product state representations (2007)
Perez-García, David, Verstraete, Frank, Wolf, Michael M., Cirac, J. Ignacio
Dividing Quantum Channels (2006)
Wolf, Michael M., Cirac, J. Ignacio
We 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...
The computational complexity of PEPS (2006)
Schuch, Norbert, Wolf, Michael M., Verstraete, Frank, Cirac, J. Ignacio
We 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...
Quantum Phase Transitions in Matrix Product Systems (2006)
Wolf, Michael M., Ortiz, Gerardo, Verstraete, Frank, Cirac, J. Ignacio
We investigate quantum phase transitions (QPTs) in spin chain systems characterized by local Hamiltonians with matrix product ground states. We show how to theoretically engineer such QPT points...
Numerical Computation of Localizable Entanglement in Spin Chains (2006)
Popp, Markus, Verstraete, Frank, Martin-Delgado, M. A., Cirac, J. Ignacio
Criticality, the area Law, and the Computational Power of Projected Entangled Pair States (2006)
Verstraete, Frank, Wolf, Michael M., Pérez-García, David, Cirac, J. Ignacio
Ground-state cooling of atoms in optical lattices (2006)
Popp, Markus, Garcia-Ripoll, Juan-José, Vollbrecht, Karl G., Cirac, J. Ignacio
Cooling toolbox for atoms in optical lattices (2006)
Popp, Markus, Garcia-Ripoll, Juan-José, Vollbrecht, Karl G. H., Cirac, J. Ignacio
Quantum teleportation between light and matter (2006)
Sherson, J. F., Krauter, H., Olsson, R. K., Julsgaard, B., Hammerer, Klemens, Cirac, J. Ignacio, ...
Quantum Phase Transitions in Matrix Product Systems (2006)
Wolf, Michael M., Ortiz, Gerardo, Verstraete, Frank, Cirac, J. Ignacio
Projected Entangled States: Properties and Applications (2006)
Verstraete, Frank, Wolf, Michael, Pérez-García, David, Cirac, J. Ignacio
Quantum states on Harmonic lattices (2005)
Schuch, Norbert, Cirac, J. Ignacio, Wolf, Michael M.
We investigate bosonic Gaussian quantum states on an infinite cubic lattice in arbitrary spatial dimensions. We derive general properties of such states as ground states of quadratic Hamiltonians for...
Quantum Key Distillation from Gaussian States by Gaussian Operations (2005)
Navascués, M., Bae, J., Cirac, J. Ignacio, Lewestein, M., Sanpera, A., Acín, A.
Renormalization-Group Transformations on Quantum States (2005)
Verstraete, Frank, Cirac, J. Ignacio, Latorre, J. I., Rico, E., Wolf, Michael M.
Hilbert's 17th Problem and the Quantumness of States (2005)
Korbicz, J. K., Cirac, J. Ignacio, Wehr, Jan, Lewenstein, M.
Quantum Benchmark for Storage and Transmission of Coherent States (2005)
Hammerer, Klemens, Wolf, Michael M., Polzik, Eugene S., Cirac, J. Ignacio
Localizable entanglement (2005)
Popp, Markus, Verstraete, Frank, Martín-Delgado, Miguel Angel, Cirac, J. Ignacio
Sequential Generation of Entangled Multiqubit States (2005)
Schön, Christian, Solano, Enrique, Verstraete, Frank, Cirac, J. Ignacio, Wolf, Michael M.
Resonant Transmission of Cold Atoms through Subwavelength Apertures (2005)
Moreno, Esteban, Fernández-Domínguez, A. I., Cirac, J. Ignacio, García-Vidal, F. J., Martín-Moreno, L.
Atomic quantum gases in Kagomé lattices (2004)
Santos, L., Baranov, M. A., Cirac, J. Ignacio, Everts, H. U., Fehrmann, H., Lewenstein, M.
Gaussian entanglement of formation (2004)
Wolf, Michael M., Giedke, Geza, Krüger, O., Werner, R. F., Cirac, J. Ignacio
Variational ansatz for the superfluid Mott-insulator transition in optical lattices (2004)
Garcia-Ripoll, Juan J., Cirac, J. Ignacio, Zoller, P., Kollath, C., Schollwock, U., Von Delft, J.
Quantum Optical Implementation of Quantum Information Processing (2004)
Zoller, P., Cirac, J. Ignacio, Duan, Luming, García-Ripoll, Juan J.
Defect-Suppressed Atomic Crystals in an Optical Lattice (2003)
Rabl, P., Daley, A. J., Fedichev, P. O., Cirac, J. Ignacio, Zoller, P.
Entanglement generation and Hamiltonian simulation in continuous-variable systems (2003)
Kraus, Barbara, Hammerer, Klemens, Giedke, Géza, Cirac, J. Ignacio
Entanglement of Formation for Symmetric Gaussian States (2003)
Giedke, Géza, Wolf, Michael M., Krüger, O., Werner, R. E., Cirac, J. Ignacio
Entanglement properties of Gaussian states (2003)
Kraus, Barbara, Giedke, Géza, Lewenstein, Maciej, Cirac, J. Ignacio
Separable states can be used to distribute entanglement (2003)
Cubitt, Toby S., Verstraete, Frank, Dür, W., Cirac, J. Ignacio
Characterization of Gaussian operations and distillation of Gaussian states (2002)
Giedke, Géza, Cirac, J Ignacio
We 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 that can be performed on Gaussian...
Three-dimensional theory for interaction between atomic ensembles and free-space light (2002)
Duan, L. M., Cirac, J. Ignacio, Zoller, P.
Atomic ensembles have shown to be a promising candidate for implementations of quantum information processing by many recently discovered schemes. All these schemes are based on the interaction...
Creation of a molecular condensate by dynamically melting a Mott insulator (2002)
Jaksch, D., Venturi, V., Cirac, J. Ignacio, Williams, C. J., Zoller, P.
We propose the creation of a molecular Bose-Einstein condensate by loading an atomic condensate into an optical lattice and driving it into a Mott insulator with exactly two atoms per site. Molecules...
Fermionizing a small gas of ultracold bosons (2002)
Paredes, Belen, Zoller, P., Cirac, J. Ignacio
We study the physics of a rapidly rotating gas of ultracold atomic bosons, with an internal degree of freedom. We show that in the limit of rapid rotation of the trap the problem exactly maps onto...
Quantum entanglement in spinor Bose-Einstein condensates (2002)
Duan, L. M., Cirac, J. Ignacio, Zoller, P.
We propose a scheme to generate and detect various kinds of quantum entanglement in a spin-1 Bose-Einstein condensate. It is shown that substantial many-particle entanglement can be generated...
Dynamically turning off interactions in a two-component condensate (2002)
Jaksch, D., Cirac, J. Ignacio, Zoller, P.
We propose a mechanism to change the interaction strengths of a two-component condensate. It is shown that the application of π/2 pulses allows us to alter the effective interspecies-interaction...
Interaction cost of nonlocal gates (2002)
Vidal, G., Hammerer, Klemens, Cirac, J. Ignacio
We introduce the interaction cost of a nonlocal gate as the minimal time of interaction required to perform the gate when assisting the process with fast local unitaries. This cost, of interest both...
Storing Quantum Dynamics in Quantum States (2002)
Vidal, G., Masanes, L., Cirac, J. Ignacio
We show how to encode quantum dynamics in the state of a quantum system, in such a way that the system can be used to stochastically perform, at a later time, the stored transformation on some other...
Irreversibility in asymptotic manipulations of a distillable entangled state (2002)
We provide an example of a distillable bipartite mixed state such that, even in the asymptotic limit, more pure-state entanglement is required to create it than can be distilled from it. Thus, we...