6,909 research outputs found
Mesure du de plus court temps de vie dans le cadre de l'expérience LHCb
L'expérience LHCb est une expérience de seconde génération dédiée à l'étude de la violation de la symétrie CP dans les systèmes des hadrons beaux. La symétrie CP est la combinaison de la symétrie de conjugaison de charge (C) qui échange particule et anti-particule et de la symétrie de parité (P) qui inverse les directions d'espace. L'ensemble des hadrons beaux est produit. Son détecteur sera l'un des quatre devant être installé sur le grand collisionneur de protons (LHC). Dans l'objectif de tester la validité du modèle standard dans ce domaine, il sera nécessaire d'effectuer une série de mesures de précision concernant les paramètres qui définissent la violation de CP et les grandeurs physiques caractérisant le mélange et la désintégration des hadrons beaux. Ce document décrit la probabilité de mesure de la différence relative de largeur de désintégration dans le système du méson () à travers l'étude du canal $B_{s}^{0}\rightarrow\,D_{s}^{+}\,D_{s}^{-}
I Have Chicken Fat in My Urine! a Case of Candida Tropicalis Induced Emphysematous Pyelitis
A patient with uncontrolled diabetes mellitus presented with fever and flank pain. A computed tomography scan showed free air within both collecting systems. A diagnosis of emphysematous pyelitis was made after other alternative diagnoses were ruled out. Urine culture grew Candida tropicalis. The emphysematous pyelitis resolved with conservative management using antifungal therapy
The Mariner 5 flight path and its determination from tracking data
Mariner 5 flight path and its determination from tracking dat
Fundamental Limits on the Speed of Evolution of Quantum States
This paper reports on some new inequalities of
Margolus-Levitin-Mandelstam-Tamm-type involving the speed of quantum evolution
between two orthogonal pure states. The clear determinant of the qualitative
behavior of this time scale is the statistics of the energy spectrum. An
often-overlooked correspondence between the real-time behavior of a quantum
system and the statistical mechanics of a transformed (imaginary-time)
thermodynamic system appears promising as a source of qualitative insights into
the quantum dynamics.Comment: 6 pages, 1 eps figur
Efficient generation of random multipartite entangled states using time optimal unitary operations
We review the generation of random pure states using a protocol of repeated
two qubit gates. We study the dependence of the convergence to states with Haar
multipartite entanglement distribution. We investigate the optimal generation
of such states in terms of the physical (real) time needed to apply the
protocol, instead of the gate complexity point of view used in other works.
This physical time can be obtained, for a given Hamiltonian, within the
theoretical framework offered by the quantum brachistochrone formalism. Using
an anisotropic Heisenberg Hamiltonian as an example, we find that different
optimal quantum gates arise according to the optimality point of view used in
each case. We also study how the convergence to random entangled states depends
on different entanglement measures.Comment: 5 pages, 2 figures. New title, improved explanation of the algorithm.
To appear in Phys. Rev.
Multi-Qubit Systems: Highly Entangled States and Entanglement Distribution
A comparison is made of various searching procedures, based upon different
entanglement measures or entanglement indicators, for highly entangled
multi-qubits states. In particular, our present results are compared with those
recently reported by Brown et al. [J. Phys. A: Math. Gen. 38 (2005) 1119]. The
statistical distribution of entanglement values for the aforementioned
multi-qubit systems is also explored.Comment: 24 pages, 3 figure
A genuine maximally seven-qubit entangled state
Contrary to A.Borras et al.'s [1] conjecture, a genuine maximally seven-qubit
entangled state is presented. We find a seven-qubit state whose marginal
density matrices for subsystems of 1,2- qubits are all completely mixed and for
subsystems of 3-qubits is almost completely mixed
Time-optimal CNOT between indirectly coupled qubits in a linear Ising chain
We give analytical solutions for the time-optimal synthesis of entangling
gates between indirectly coupled qubits 1 and 3 in a linear spin chain of three
qubits subject to an Ising Hamiltonian interaction with equal coupling plus
a local magnetic field acting on the intermediate qubit. The energy available
is fixed, but we relax the standard assumption of instantaneous unitary
operations acting on single qubits. The time required for performing an
entangling gate which is equivalent, modulo local unitary operations, to the
between the indirectly coupled qubits 1 and 3 is
, i.e. faster than a previous estimate based on a similar
Hamiltonian and the assumption of local unitaries with zero time cost.
Furthermore, performing a simple Walsh-Hadamard rotation in the Hlibert space
of qubit 3 shows that the time-optimal synthesis of the (which acts as the identity when the control qubit 1 is in the state
, while if the control qubit is in the state the target
qubit 3 is flipped as ) also requires the same
time .Comment: 9 pages; minor modification
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