Entanglement dynamics during decoherence (2009)
Paz, Juan Pablo, Roncaglia, Augusto J.
The evolution of the entanglement between oscillators that interact with the same environment displays highly non-trivial behavior in the long time regime. When the oscillators only interact through...
Redundancy of classical and quantum correlations during decoherence (2009)
Paz, Juan Pablo, Roncaglia, Augusto J.
We analyze the time dependence of entanglement and total correlations between a system and fractions of its environment in the course of decoherence. For the quantum Brownian motion model we show...
Selective and Efficient Quantum Process Tomography (2009)
Bendersky, Ariel, Pastawski, Fernando, Paz, Juan Pablo
In this paper we describe in detail and generalize a method for quantum process tomography that was presented in [A. Bendersky, F. Pastawski, J. P. Paz, Physical Review Letters 100, 190403 (2008)]....
General theory of measurement with two copies of a quantum state (2009)
Bendersky, Ariel, Paz, Juan Pablo, Cunha, Marcelo Terra
We analyze the possible results of the most general measurement on two copies of a quantum state. We show that $\mu$ can label a set of outcomes of such measurement if and only if there is a family...
Paz, Juan Pablo, Roncaglia, Augusto J.
We study the dynamics of the entanglement between two oscillators that are initially prepared in a general two-mode Gaussian state and evolve while coupled to the same environment. In a previous...
Decoherence of Bell states by local interactions with a dynamic spin environment (2008)
Cormick, Cecilia, Paz, Juan Pablo
We study the evolution of a system of two qubits, each of which interacts locally with a spin chain with nontrivial internal Hamiltonian. We present an exact solution to this problem and analyze the...
Selective Efficient Quantum Process Tomography (2008)
Bendersky, Ariel, Pastawski, Fernando, Paz, Juan Pablo
We present a new method for quantum process tomography. The method enables us to efficiently estimate, with fixed precision, any of the parameters characterizing a quantum channel. It is selective...
Dynamics of the entanglement between two oscillators in the same environment (2008)
Paz, Juan Pablo, Roncaglia, Augusto J.
We provide a complete characterization of the evolution of entanglement between two oscillators coupled to a common environment. For initial Gaussian states we identify three phases with different...
Decoherence induced by a dynamic spin environment (I): The universal regime (2007)
Cormick, Cecilia, Paz, Juan Pablo
This article analyzes the decoherence induced on a single qubit by the interaction with a spin chain with nontrivial internal dynamics (XY-type interactions). The aim of the paper is to study the...
Cormick, Cecilia, Paz, Juan Pablo
This article studies the decoherence induced on a system of two qubits by local interactions with a spin chain with nontrivial internal dynamics (governed by an XY Hamiltonian). Special attention is...
Einstein against quantum mechanics: randomness, ignorance and our ignorance about randomness (2007)
Albert Einstein made fundamental contributions to the development of quantum mechanics. However, he was never satisfied with the quantum worldview. In fact, during most of his life he attempted to...
Signatures of non-locality in the first-order coherence of the scattered light (2007)
Cañizares, Priscilla, Görler, Tobias, Paz, Juan Pablo, Morigi, Giovanna, Schleich, Wolfgang
The spatial coherence of an atomic wavepacket can be detected in the scattered photons, even when the center-of-mass motion is in the quantum coherent superposition of two distant, non-overlapping...
Interference in discrete Wigner functions (2006)
Cormick, Cecilia, Paz, Juan Pablo
We analyse some features of the class of discrete Wigner functions that was recently introduced by Gibbons et al. to represent quantum states of systems with power-of-prime dimensional Hilbert spaces...
Universal decoherence induced by an environmental quantum phase transition (2006)
Cucchietti, Fernando Martin, Fernandez-Vidal, Sonia, Paz, Juan Pablo
Decoherence induced by coupling a system with an environment may display universal features. Here we demostrate that when the coupling to the system drives a quantum phase transition in the...
Decoherence induced by a chaotic environment: A quantum walker with a complex coin (2005)
Ermann, Leonardo, Paz, Juan Pablo, Saraceno, Marcos
We study the differences between the process of decoherence induced by chaotic and regular environments. For this we analyze a family of simple models wich contain both regular and chaotic...
Classicality in discrete Wigner functions (2005)
Cormick, Cecilia, Galvao, Ernesto F., Gottesman, Daniel, Paz, Juan Pablo, Pittenger, Arthur O.
Gibbons et al. [Phys. Rev. A 70, 062101(2004)] have recently defined a class of discrete Wigner functions W to represent quantum states in a Hilbert space with finite dimension. We show that the only...
Paz, Juan Pablo, Roncaglia, Augusto Jose, Saraceno, Marcos
We analyze and further develop a new method to represent the quantum state of a system of $n$ qubits in a phase space grid of $N\times N$ points (where $N=2^n$). The method, which was recently...
Quantum algorithms for phase space tomography (2003)
Paz, Juan Pablo, Roncaglia, Augusto J., Saraceno, Marcos
We present efficient circuits that can be used for the phase space tomography of quantum states. The circuits evaluate individual values or selected averages of the Wigner, Kirkwood and Husimi...
Decoherence and recoherence from vacuum fluctuations near a conducting plate (2003)
Mazzitelli, Francisco D., Paz, Juan Pablo, Villanueva, Alejandro
The interaction between particles and the electromagnetic field induces decoherence generating a small suppression of fringes in an interference experiment. We show that if a double slit--like...
A quantum gate array can be programmed to evaluate the expectation value of any operator (2003)
Paz, Juan Pablo, Roncaglia, Augusto
A programmable gate array is a circuit whose action is controlled by input data. In this letter we describe a special--purpose quantum circuit that can be programmed to evaluate the expectation value...
Testing Integrability with a Single Bit of Quantum Information (2003)
Poulin, David, Laflamme, Raymond, Milburn, G. J., Paz, Juan Pablo
We show that deterministic quantum computing with a single bit (DQC1) can determine whether the classical limit of a quantum system is chaotic or integrable using O(N) physical resources, where $N$...
Testing Integrability with a Single Bit of Quantum Information (2003)
Poulin, David, Laflamme, Raymond, Milburn, G. J., Paz, Juan Pablo
We show that deterministic quantum computing with a single bit (DQC1) can determine whether the classical limit of a quantum system is chaotic or integrable using O(N) physical resources, where $N$...
Testing integrability with a single bit of quantum information (2003)
Poulin, David, Laflamme, Raymond, Milburn, G. J., Paz, Juan Pablo
We show that deterministic quantum computing with a single bit (DQC1) can determine whether the classical limit of a quantum system is chaotic or integrable using O(N) physical resources, where $N$...
Testing Integrability with a Single Bit of Quantum Information (2003)
Poulin, David, Laflamme, Raymond, Milburn, G. J., Paz, Juan Pablo
We show that deterministic quantum computing with a single bit (DQC1) can determine whether the classical limit of a quantum system is chaotic or integrable using O(N) physical resources, where $N$...
Testing Integrability with a Single Bit of Quantum Information (2003)
Poulin, David, Laflamme, Raymond, Milburn, G. J., Paz, Juan Pablo
We show that deterministic quantum computing with a single bit (DQC1) can determine whether the classical limit of a quantum system is chaotic or integrable using O(N) physical resources, where $N$...
Quantum computers in phase space (2002)
Miquel, Cesar, Paz, Juan Pablo, Saraceno, Marcos
We represent both the states and the evolution of a quantum computer in phase space using the discrete Wigner function. We study properties of the phase space representation of quantum algorithms:...
Discrete Wigner functions and the phase space representation of quantum teleportation (2002)
We present a phase space description of the process of quantum teleportation for a system with an $N$ dimensional space of states. For this purpose we define a discrete Wigner function which is a...
Decoherence for classically chaotic quantum maps (2001)
Bianucci, Pablo, Paz, Juan Pablo, Saraceno, Marcos
We study the behavior of an open quantum system, with an $N$--dimensional space of states, whose density matrix evolves according to a non--unitary map defined in two steps: A unitary step, where the...
Tomography and spectroscopy as quantum computations (2001)
Miquel, Cesar, Paz, Juan Pablo, Saraceno, Marcos, Knill, Emmanuel, Laflamme, Raymond, Negrevergne, Camille
Determining the state of a system and measuring properties of its evolution are two of the most important tasks a physicist faces. For the first purpose one can use tomography, a method that after...
Monteoliva, Diana, Paz, Juan Pablo
We study the decoherence process for an open quantum system which is classically chaotic (a quartic double well with harmonic driving coupled to a sea of harmonic oscillators). We analyze the time...
Discrete Wigner functions and the phase space representation of quantum computers (2001)
Bianucci, Pablo, Miquel, Cesar, Paz, Juan Pablo, Saraceno, Marcos
We show how to represent the state and the evolution of a quantum computer (or any system with an $N$--dimensional Hilbert space) in phase space. For this purpose we use a discrete version of the...
Environment-Induced Decoherence and the Transition From Quantum to Classical (2000)
Paz, Juan Pablo, Zurek, Wojciech Hubert
We study dynamics of quantum open systems, paying special attention to those aspects of their evolution which are relevant to the transition from quantum to classical. We begin with a discussion of...
Decoherence and the rate of entropy production in chaotic quantum systems (2000)
Monteoliva, Diana, Paz, Juan Pablo
We show that for an open quantum system which is classically chaotic (a quartic double well with harmonic driving coupled to a sea of harmonic oscillators) the rate of entropy production has, as a...
Quantum limit of decoherence: Environment induced superselection of energy eigenstates (1998)
Paz, Juan Pablo, Zurek, Wojciech Hubert
We investigate decoherence in the limit where the interaction with the environment is weak and the evolution is dominated by the self Hamiltonian of the system. We show that in this case quantized...
Continuous Error Correction (1997)
Paz, Juan Pablo, Zurek, Wojciech Hubert
We propose a new approach to study the evolution of a quantum state that is encoded in a system which is continuously subject to the operations required to implement a quantum error correcting code....
Quantum computation with phase drift errors (1997)
Miquel, Cesar, Paz, Juan Pablo, Zurek, Wojciech Hubert
We present results of numerical simulations of the evolution of an ion trap quantum computer made out of 18 ions which are subject to a sequence of nearly 15000 laser pulses in order to find the...
Decoherence and Initial Correlations in Quantum Brownian Motion (1996)
Romero, Luciana Dávila, Paz, Juan Pablo
We analyze the evolution of a quantum Brownian particle starting from an initial state that contains correlations between this system and its environment. Using a path integral approach, we obtain a...
Zurek, Wojciech Hubert, Paz, Juan Pablo
Violation of correspondence principle may occur for very macroscopic byt isolated quantum systems on rather short timescales as illustrated by the case of Hyperion, the chaotically tumbling moon of...
Perfect Quantum Error Correction Code (1996)
Laflamme, Raymond, Miquel, Cesar, Paz, Juan Pablo, Zurek, Wojciech Hubert
We present a quantum error correction code which protects a qubit of information against general one qubit errors which maybe caused by the interaction with the environment. To accomplish this, we...
Factoring in a Dissipative Quantum Computer (1996)
Miquel, Cesar, Paz, Juan Pablo, Perazzo, Roberto
We describe an array of quantum gates implementing Shor's algorithm for prime factorization in a quantum computer. The array includes a circuit for modular exponentiation with several subcomponents...
Quantum Origin of Noise and Fluctuations in Cosmology (1995)
Hu, B. L., Paz, Juan Pablo, Zhang, Yuhong
We address two basic issues in the theory of galaxy formation from fluctuations of quantum fields: 1) the nature and origin of noise and fluctuations and 2) the conditions for using a classical...
Dissipation and Decoherence in Mean Field Theory (1995)
Habib, Salman, Kluger, Yuval, Mottola, Emil, Paz, Juan Pablo
The time evolution of a closed system of mean fields and fluctuations is Hamiltonian, with the canonical variables parameterizing the general time-dependent Gaussian density matrix of the system....
Non-Equilibrium Quantum Fields in the Large N Expansion (1994)
Cooper, Fred, Habib, Salman, Kluger, Yuval, Mottola, Emil, Paz, Juan Pablo, Anderson, Paul R.
An effective action technique for the time evolution of a closed system consisting of one or more mean fields interacting with their quantum fluctuations is presented. By marrying large $N$ expansion...
Nonequilibrium Quantum Dynamics Of Disoriented Chiral Condensates (1994)
Cooper, Fred, Kluger, Yuval, Mottola, Emil, Paz, Juan Pablo
The nonequilibrium dynamics of the chiral phase transition expected during the expansion of the quark-qluon plasma produced in a high energy hadron or heavy ion collision is studied in the O(4)...
Decoherence, Chaos, and the Second Law (1994)
Zurek, Wojciech Hubert, Paz, Juan Pablo
We investigate implications of decoherence for quantum systems which are classically chaotic. We show that, in open systems, the rate of von Neumann entropy production quickly reaches an asymptotic...
Decoherence in Quantum Brownian Motion (1994)
We examine the dependence of decoherence on the spectral density of the environment as well as on the initial state of the system. We use two simple examples to illustrate some important effects. The...
Environment--Induced Decoherence, Classicality and Consistency of Quantum Histories (1993)
Paz, Juan Pablo, Zurek, Wojciech Hubert
We prove that for an open system, in the Markovian regime, it is always possible to construct an infinite number of non trivial sets of histories that exactly satisfy the probability sum rules. In...
Minisuperspace as a Quantum Open System (1993)
Hu, B. L., Paz, Juan Pablo, Sinha, Sukanya
We trace the development of ideas on dissipative processes in chaotic cosmology and on minisuperspace quantum cosmology from the time Misner proposed them to current research. We show 1) how the...