77 research outputs found
A General Framework for Recursive Decompositions of Unitary Quantum Evolutions
Decompositions of the unitary group U(n) are useful tools in quantum
information theory as they allow one to decompose unitary evolutions into local
evolutions and evolutions causing entanglement. Several recursive
decompositions have been proposed in the literature to express unitary
operators as products of simple operators with properties relevant in
entanglement dynamics. In this paper, using the concept of grading of a Lie
algebra, we cast these decompositions in a unifying scheme and show how new
recursive decompositions can be obtained. In particular, we propose a new
recursive decomposition of the unitary operator on qubits, and we give a
numerical example.Comment: 17 pages. To appear in J. Phys. A: Math. Theor. This article replaces
our earlier preprint "A Recursive Decomposition of Unitary Operators on N
Qubits." The current version provides a general method to generate recursive
decompositions of unitary evolutions. Several decompositions obtained before
are shown to be as a special case of this general procedur
Carbapenem resistance in gram-negative bacilli isolates in an iranian 1000-bed tertiary hospital
Objective: Carbapenems are beta-lactamase antibiotics, presently considered as most potent agents for treatment of infections caused by Gram-negative bacilli. The aim of this study was to determine resistance of Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumonniae as prevalent nosocomial agents to commonly used antibiotics including carbapenems such as imipenem and meropenem. Methodology: A total of 202 gram-negative bacilli including K.pneumoniae, P aeruginosa and A.baumannii isolated from hospitalized patients in Milad hospital of Tehran were subject for susceptibility testing. Susceptibility testing was performed by disk diffusion and MIC methods as recommended by Clinical Laboratory Standards Institute (CLSI) Results: All isolates of K. pneumonia were susceptible to imipenem and meropenem. Resistance in non-fermenting gram-negative bacilli (NFGB) was prevalent. P.aeruginosa isolates exhibited 7.5 and 40.2 resistance to imipenem and meropenem respectively. The majority isolates of Acinetobacter baumannii were multi-drug resistant and resistance of this organism to imipenem and meropenem was 27.7 and 38.5 respectively. Conclusions: Our study revealed that in spite of resistance of K.pneumoniae to commonly used antibiotics, all isolates were susceptible to imipenem and meropeem. More than 80 isolates of A .bammanni were resistant to commonly used antibiotics. About 40.2 isolates of P.aeruginosa and (38.5) isolates of A.baumannii were resistant to meropenem respectively
Factorizations and Physical Representations
A Hilbert space in M dimensions is shown explicitly to accommodate
representations that reflect the prime numbers decomposition of M.
Representations that exhibit the factorization of M into two relatively prime
numbers: the kq representation (J. Zak, Phys. Today, {\bf 23} (2), 51 (1970)),
and related representations termed representations (together with
their conjugates) are analysed, as well as a representation that exhibits the
complete factorization of M. In this latter representation each quantum number
varies in a subspace that is associated with one of the prime numbers that make
up M
Realisation of a programmable two-qubit quantum processor
The universal quantum computer is a device capable of simulating any physical
system and represents a major goal for the field of quantum information
science. Algorithms performed on such a device are predicted to offer
significant gains for some important computational tasks. In the context of
quantum information, "universal" refers to the ability to perform arbitrary
unitary transformations in the system's computational space. The combination of
arbitrary single-quantum-bit (qubit) gates with an entangling two-qubit gate is
a gate set capable of achieving universal control of any number of qubits,
provided that these gates can be performed repeatedly and between arbitrary
pairs of qubits. Although gate sets have been demonstrated in several
technologies, they have as yet been tailored toward specific tasks, forming a
small subset of all unitary operators. Here we demonstrate a programmable
quantum processor that realises arbitrary unitary transformations on two
qubits, which are stored in trapped atomic ions. Using quantum state and
process tomography, we characterise the fidelity of our implementation for 160
randomly chosen operations. This universal control is equivalent to simulating
any pairwise interaction between spin-1/2 systems. A programmable multi-qubit
register could form a core component of a large-scale quantum processor, and
the methods used here are suitable for such a device.Comment: 7 pages, 4 figure
Pauli Diagonal Channels Constant on Axes
We define and study the properties of channels which are analogous to unital
qubit channels in several ways. A full treatment can be given only when the
dimension d is a prime power, in which case each of the (d+1) mutually unbiased
bases (MUB) defines an axis. Along each axis the channel looks like a
depolarizing channel, but the degree of depolarization depends on the axis.
When d is not a prime power, some of our results still hold, particularly in
the case of channels with one symmetry axis. We describe the convex structure
of this class of channels and the subclass of entanglement breaking channels.
We find new bound entangled states for d = 3.
For these channels, we show that the multiplicativity conjecture for maximal
output p-norm holds for p=2. We also find channels with behavior not exhibited
by unital qubit channels, including two pairs of orthogonal bases with equal
output entropy in the absence of symmetry. This provides new numerical evidence
for the additivity of minimal output entropy
Enumeration of reversible functions and its application to circuit complexity
We review combinational results to enumerate and classify reversible functions and investigate the application to circuit complexity. In particularly, we consider the effect of negating and permuting input and output variables and the effect of applying linear and affine transformations to inputs and outputs. We apply the results to reversible circuits and prove that minimum circuit realizations of functions in the same equivalence class differ at most in a linear number of gates in pres- ence of negation and permutation and at most in a quadratic number of gates in presence of linear and affine transformations
Pankiller effect of prolonged exposure to menadione on glioma cells: potentiation by vitamin C
Denken erzahlen. Reprasentationen des Intellekts bei Robert Musil und Paul Valery. Von Olav Kramer. Berlin: de Gruyter, 2009. xi + 591 Seiten. 109,95.
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