E. Brion - Academia.edu (original) (raw)

Papers by E. Brion

The European Physical Journal B, 2012

ABSTRACT We numerically simulate the dynamics of atomic clusters aggregation deposited on a surfa... more ABSTRACT We numerically simulate the dynamics of atomic clusters aggregation deposited on a surface interacting with the growing island. We make use of the well-known DLA model but replace the underlying diffusion equation by the Smoluchowski equation which results in a drifted DLA model and anisotropic jump probabilities. The shape of the structures resulting from their aggregation-limited random walk is affected by the presence of a Laplacian potential due to, for instance, the surface stress field. We characterize the morphologies we obtain by their Hausdorff fractal dimension as well as the so-called external fractal dimension. We compare our results to previously published experimental results for antimony and silver clusters deposited onto graphite surface.

NATO Science Series II: Mathematics, Physics and Chemistry, 2005

We numerically simulate the dynamics of aggregation of interacting atomic clusters deposited on a... more We numerically simulate the dynamics of aggregation of interacting atomic clusters deposited on a surface. We show that the shape of the structures resulting from their aggregation-limited random walk is affected by the presence of a binary interparticle Laplacian potential due to, for instance, the surface stress field. We characterize the morphologies we obtain by their Hausdorff fractal dimension as well as the so-called external fractal dimension, which appears more sensitive to the potential. We demonstrate the relevance of our model by comparing it to previously published experimental results for antymony and silver clusters deposited onto graphite surface.

... measurements only and one-way quantum computation. Author(s): Philippe Jorrand;Simon Perdrix.... more ... measurements only and one-way quantum computation. Author(s): Philippe Jorrand;Simon Perdrix. Entangled electron spin states at work in spin dependent molecular processes. Author(s): KM Salikhov. Non-Holonomic Control I. Author(s ...

We show that multidimensional Zeno effect combined with non-holonomic control allows to efficient... more We show that multidimensional Zeno effect combined with non-holonomic control allows to efficiently protect quantum systems from decoherence by a method similar to classical coding. Contrary to the conventional approach, our method is applicable to arbitrary error-inducing Hamiltonians and general quantum systems. We also propose algorithms of finding encoding that approaches the Hamming upper bound along with methods of practical realizations of the encodings. Two new codes protecting 2 information qubits out of 7 and 4 information qubits out of 9 against a single error with arbitrarily small probability of failure are constructed as an example.

Europhysics Letters (EPL), 2004

... transformation. We start with a geometric illustration of the regular Zeno effect for a simpl... more ... transformation. We start with a geometric illustration of the regular Zeno effect for a simple two-level system. ... vector. The Pauli matrices have zero trace, and the normalization condition Tr ̂ρ = 1 holds due to the presence of the identity matrix ̂I. ...

Journal of Optics B: Quantum and Semiclassical Optics, 2005

We show that the multidimensional Zeno effect combined with non-holonomic control allows one to e... more We show that the multidimensional Zeno effect combined with non-holonomic control allows one to efficiently protect quantum systems from decoherence by a method similar to classical random coding. The method is applicable to arbitrary error-inducing Hamiltonians and general quantum systems. The quantum encoding approaches the Hamming upper bound for large dimension increases. Applicability of the method is demonstrated with a seven-qubit toy computer.

Physical Review A, 2005

The protection of the coherence of open quantum systems against the influence of their environmen... more The protection of the coherence of open quantum systems against the influence of their environment is a very topical issue. A scheme is proposed here which protects a general quantum system from the action of a set of arbitrary uncontrolled unitary evolutions. This method draws its inspiration from ideas of standard error correction ͑ancilla adding, coding and decoding͒ and the quantum Zeno effect. A demonstration of our method on a simple atomic system-namely, a rubidium isotope-is proposed.

Quantum Informatics 2004, 2005

In this paper, we show how the non-holonomic control technique can be employed to build completel... more In this paper, we show how the non-holonomic control technique can be employed to build completely controlled quantum devices. Examples of such controlled structures are provided.

Quantum Informatics 2004, 2005

In this paper, we present a realistic application of the coherence protection method proposed in ... more In this paper, we present a realistic application of the coherence protection method proposed in the previous article. A qubit of information encoded on the two spin states of a Rubidium isotope is protected from the action of electric and magnetic fields.

Physical Review A, 2007

We suggest a novel way to use strong Rydberg dipole-dipole interactions in order to induce non-tr... more We suggest a novel way to use strong Rydberg dipole-dipole interactions in order to induce non-trivial conditional dynamics in individual-atom systems and mesoscopic ensembles. Contrary to previous works, we suggest to excite atoms into different Rydberg states, which results in a potentially richer dynamical behaviour. Specifically, we investigate systems of individual hydrogenlike atoms or mesoscopic ensembles excited into high-lying hydrogen-like s, p or d states and show how to perform three-qubit conditional dynamics on the information they contain through a proper use of dipole-dipole interaction induced energy shifts.

Journal of Physics B: Atomic, Molecular and Optical Physics, 2011

In this paper, we review an open-loop evolution control method, called the nonholonomic control, ... more In this paper, we review an open-loop evolution control method, called the nonholonomic control, based on the alternate application of only two physical perturbations for timings which play the role of adjustable control parameters. We present the algorithm which allows one to explicitly compute the pulse sequence achieving any arbitrarily prescribed unitary evolution in a nonholonomic system, i.e. a system subject to two physical perturbations which, together with the natural Hamiltonian of the system, span the entire Lie algebra u(N ). We moreover expose two extensions of our method to open quantum systems which, respectively, aim at preserving the information stored in the system and safely processing this information. The first is based on a generalization of the quantum Zeno effect, while the second is inspired by decoupling pulse techniques. The most important feature of the methods presented here is their universality: they indeed do not rely on any specific assumption on the system, which in particular is not bound to be a collection of two-level systems, or the error model considered, as is usually the case in the literature. Numerical and physical applications of our techniques are also provided.

Journal of Physics B: Atomic, Molecular and Optical Physics, 2007

ABSTRACT In this paper, we propose a neutral atom implementation of the two-qubit conditional pha... more ABSTRACT In this paper, we propose a neutral atom implementation of the two-qubit conditional phase gate, based on the large Rydberg–Rydberg interaction induced energy shift. Contrary to previous proposals, this gate does not substantially populate the Rydberg levels. After describing the model in detail, we provide numerical simulations and discuss the performance of our gate. In particular we address the influence on the fidelity of spontaneous emission and atomic motion.

Journal of Physics A: Mathematical and Theoretical, 2007

This paper deals with different ways to extract the effective two-dimensional lower level dynamic... more This paper deals with different ways to extract the effective two-dimensional lower level dynamics of a lambda system excited by off-resonant laser beams. We present a commonly used procedure for elimination of the upper level, and we show that it may lead to ambiguous results. To overcome this problem and better understand the applicability conditions of this scheme, we review two rigorous methods which allow us both to derive an unambiguous effective two-level Hamiltonian of the system and to quantify the accuracy of the approximation achieved: the first one relies on the exact solution of the Schrödinger equation, while the second one resorts to the Green's function formalism and the Feshbach projection operator technique.

The European Physical Journal B, 2012

ABSTRACT We numerically simulate the dynamics of atomic clusters aggregation deposited on a surfa... more ABSTRACT We numerically simulate the dynamics of atomic clusters aggregation deposited on a surface interacting with the growing island. We make use of the well-known DLA model but replace the underlying diffusion equation by the Smoluchowski equation which results in a drifted DLA model and anisotropic jump probabilities. The shape of the structures resulting from their aggregation-limited random walk is affected by the presence of a Laplacian potential due to, for instance, the surface stress field. We characterize the morphologies we obtain by their Hausdorff fractal dimension as well as the so-called external fractal dimension. We compare our results to previously published experimental results for antimony and silver clusters deposited onto graphite surface.

NATO Science Series II: Mathematics, Physics and Chemistry, 2005

EPL (Europhysics Letters), 2010

ABSTRACT We propose a technique that allows to simultaneously perform universal control of the ev... more ABSTRACT We propose a technique that allows to simultaneously perform universal control of the evolution operator of a system and compensate for the first-order contribution of any Hermitian constant noise and the action of the environment. We show that, at least, a three-valued Hamiltonian is needed in order to protect the system against any such noise and propose an explicit algorithm for finding an appropriate control sequence. This algorithm is applied to numerically design a safe gate in an atomic qutrit.

The European Physical Journal B, 2012

ABSTRACT We numerically simulate the dynamics of atomic clusters aggregation deposited on a surfa... more ABSTRACT We numerically simulate the dynamics of atomic clusters aggregation deposited on a surface interacting with the growing island. We make use of the well-known DLA model but replace the underlying diffusion equation by the Smoluchowski equation which results in a drifted DLA model and anisotropic jump probabilities. The shape of the structures resulting from their aggregation-limited random walk is affected by the presence of a Laplacian potential due to, for instance, the surface stress field. We characterize the morphologies we obtain by their Hausdorff fractal dimension as well as the so-called external fractal dimension. We compare our results to previously published experimental results for antimony and silver clusters deposited onto graphite surface.

NATO Science Series II: Mathematics, Physics and Chemistry, 2005

We numerically simulate the dynamics of aggregation of interacting atomic clusters deposited on a... more We numerically simulate the dynamics of aggregation of interacting atomic clusters deposited on a surface. We show that the shape of the structures resulting from their aggregation-limited random walk is affected by the presence of a binary interparticle Laplacian potential due to, for instance, the surface stress field. We characterize the morphologies we obtain by their Hausdorff fractal dimension as well as the so-called external fractal dimension, which appears more sensitive to the potential. We demonstrate the relevance of our model by comparing it to previously published experimental results for antymony and silver clusters deposited onto graphite surface.

... measurements only and one-way quantum computation. Author(s): Philippe Jorrand;Simon Perdrix.... more ... measurements only and one-way quantum computation. Author(s): Philippe Jorrand;Simon Perdrix. Entangled electron spin states at work in spin dependent molecular processes. Author(s): KM Salikhov. Non-Holonomic Control I. Author(s ...

We show that multidimensional Zeno effect combined with non-holonomic control allows to efficient... more We show that multidimensional Zeno effect combined with non-holonomic control allows to efficiently protect quantum systems from decoherence by a method similar to classical coding. Contrary to the conventional approach, our method is applicable to arbitrary error-inducing Hamiltonians and general quantum systems. We also propose algorithms of finding encoding that approaches the Hamming upper bound along with methods of practical realizations of the encodings. Two new codes protecting 2 information qubits out of 7 and 4 information qubits out of 9 against a single error with arbitrarily small probability of failure are constructed as an example.

Europhysics Letters (EPL), 2004

... transformation. We start with a geometric illustration of the regular Zeno effect for a simpl... more ... transformation. We start with a geometric illustration of the regular Zeno effect for a simple two-level system. ... vector. The Pauli matrices have zero trace, and the normalization condition Tr ̂ρ = 1 holds due to the presence of the identity matrix ̂I. ...

Journal of Optics B: Quantum and Semiclassical Optics, 2005

We show that the multidimensional Zeno effect combined with non-holonomic control allows one to e... more We show that the multidimensional Zeno effect combined with non-holonomic control allows one to efficiently protect quantum systems from decoherence by a method similar to classical random coding. The method is applicable to arbitrary error-inducing Hamiltonians and general quantum systems. The quantum encoding approaches the Hamming upper bound for large dimension increases. Applicability of the method is demonstrated with a seven-qubit toy computer.

Physical Review A, 2005

The protection of the coherence of open quantum systems against the influence of their environmen... more The protection of the coherence of open quantum systems against the influence of their environment is a very topical issue. A scheme is proposed here which protects a general quantum system from the action of a set of arbitrary uncontrolled unitary evolutions. This method draws its inspiration from ideas of standard error correction ͑ancilla adding, coding and decoding͒ and the quantum Zeno effect. A demonstration of our method on a simple atomic system-namely, a rubidium isotope-is proposed.

Quantum Informatics 2004, 2005

In this paper, we show how the non-holonomic control technique can be employed to build completel... more In this paper, we show how the non-holonomic control technique can be employed to build completely controlled quantum devices. Examples of such controlled structures are provided.

Quantum Informatics 2004, 2005

In this paper, we present a realistic application of the coherence protection method proposed in ... more In this paper, we present a realistic application of the coherence protection method proposed in the previous article. A qubit of information encoded on the two spin states of a Rubidium isotope is protected from the action of electric and magnetic fields.

Physical Review A, 2007

We suggest a novel way to use strong Rydberg dipole-dipole interactions in order to induce non-tr... more We suggest a novel way to use strong Rydberg dipole-dipole interactions in order to induce non-trivial conditional dynamics in individual-atom systems and mesoscopic ensembles. Contrary to previous works, we suggest to excite atoms into different Rydberg states, which results in a potentially richer dynamical behaviour. Specifically, we investigate systems of individual hydrogenlike atoms or mesoscopic ensembles excited into high-lying hydrogen-like s, p or d states and show how to perform three-qubit conditional dynamics on the information they contain through a proper use of dipole-dipole interaction induced energy shifts.

Journal of Physics B: Atomic, Molecular and Optical Physics, 2011

In this paper, we review an open-loop evolution control method, called the nonholonomic control, ... more In this paper, we review an open-loop evolution control method, called the nonholonomic control, based on the alternate application of only two physical perturbations for timings which play the role of adjustable control parameters. We present the algorithm which allows one to explicitly compute the pulse sequence achieving any arbitrarily prescribed unitary evolution in a nonholonomic system, i.e. a system subject to two physical perturbations which, together with the natural Hamiltonian of the system, span the entire Lie algebra u(N ). We moreover expose two extensions of our method to open quantum systems which, respectively, aim at preserving the information stored in the system and safely processing this information. The first is based on a generalization of the quantum Zeno effect, while the second is inspired by decoupling pulse techniques. The most important feature of the methods presented here is their universality: they indeed do not rely on any specific assumption on the system, which in particular is not bound to be a collection of two-level systems, or the error model considered, as is usually the case in the literature. Numerical and physical applications of our techniques are also provided.

Journal of Physics B: Atomic, Molecular and Optical Physics, 2007

ABSTRACT In this paper, we propose a neutral atom implementation of the two-qubit conditional pha... more ABSTRACT In this paper, we propose a neutral atom implementation of the two-qubit conditional phase gate, based on the large Rydberg–Rydberg interaction induced energy shift. Contrary to previous proposals, this gate does not substantially populate the Rydberg levels. After describing the model in detail, we provide numerical simulations and discuss the performance of our gate. In particular we address the influence on the fidelity of spontaneous emission and atomic motion.

Journal of Physics A: Mathematical and Theoretical, 2007

This paper deals with different ways to extract the effective two-dimensional lower level dynamic... more This paper deals with different ways to extract the effective two-dimensional lower level dynamics of a lambda system excited by off-resonant laser beams. We present a commonly used procedure for elimination of the upper level, and we show that it may lead to ambiguous results. To overcome this problem and better understand the applicability conditions of this scheme, we review two rigorous methods which allow us both to derive an unambiguous effective two-level Hamiltonian of the system and to quantify the accuracy of the approximation achieved: the first one relies on the exact solution of the Schrödinger equation, while the second one resorts to the Green's function formalism and the Feshbach projection operator technique.

The European Physical Journal B, 2012

ABSTRACT We numerically simulate the dynamics of atomic clusters aggregation deposited on a surfa... more ABSTRACT We numerically simulate the dynamics of atomic clusters aggregation deposited on a surface interacting with the growing island. We make use of the well-known DLA model but replace the underlying diffusion equation by the Smoluchowski equation which results in a drifted DLA model and anisotropic jump probabilities. The shape of the structures resulting from their aggregation-limited random walk is affected by the presence of a Laplacian potential due to, for instance, the surface stress field. We characterize the morphologies we obtain by their Hausdorff fractal dimension as well as the so-called external fractal dimension. We compare our results to previously published experimental results for antimony and silver clusters deposited onto graphite surface.

NATO Science Series II: Mathematics, Physics and Chemistry, 2005

EPL (Europhysics Letters), 2010

ABSTRACT We propose a technique that allows to simultaneously perform universal control of the ev... more ABSTRACT We propose a technique that allows to simultaneously perform universal control of the evolution operator of a system and compensate for the first-order contribution of any Hermitian constant noise and the action of the environment. We show that, at least, a three-valued Hamiltonian is needed in order to protect the system against any such noise and propose an explicit algorithm for finding an appropriate control sequence. This algorithm is applied to numerically design a safe gate in an atomic qutrit.