252 research outputs found
Discrete phase-space approach to mutually orthogonal Latin squares
We show there is a natural connection between Latin squares and commutative
sets of monomials defining geometric structures in finite phase-space of prime
power dimensions. A complete set of such monomials defines a mutually unbiased
basis (MUB) and may be associated with a complete set of mutually orthogonal
Latin squares (MOLS). We translate some possible operations on the monomial
sets into isomorphisms of Latin squares, and find a general form of
permutations that map between Latin squares corresponding to unitarily
equivalent mutually unbiased sets. We extend this result to a conjecture: MOLS
associated to unitarily equivalent MUBs will always be isomorphic, and MOLS
associated to unitarily inequivalent MUBs will be non-isomorphic
Maximally Entangled States of Four Nonbinary Particles
Systems of four nonbinary particles, each having three or more internal
states, exhibit maximally entangled states that are inaccessible to four
qubits. This breaks the pattern of two- and three-particle systems, in which
the existing graph states are equally accessible to binary and nonbinary
systems alike. We compare the entanglement properties of these special states
(called P-states) with those of the more familiar GHZ and cluster states
accessible to qubits. The comparison includes familiar entanglement measures,
the "steering" of states by projective measurements, and the probability that
two such measurements, chosen at random, leave the remaining particles in a
Bell state. These comparisons demonstrate not only that P-state entanglement is
stronger than the other types, but that it is maximal in a well-defined sense.
We prove that GHZ, cluster, and P-states represent all possible entanglement
classes of four-particle graph states with a prime number (>2) of states per
particle.Comment: 26 pages, 3 figures, Appendix B proof expanded slightl
Maximally Entangled States of Four Nnonbinary Particles
Systems of four nonbinary particles, with each particle having dā„3 internal states, exhibit maximally entangled states that are inaccessible to four qubits. This breaks the pattern of two- and three-particle systems, in which the existing graph states are equally accessible to binary and nonbinary systems alike. We compare the entanglement properties of these special states (called P states) with those of the more familiar Greenberger-Horne-Zeilinger (GHZ) and cluster states accessible to qubits. The comparison includes familiar entanglement measures, the āsteeringā of states by projective measurements, and the probability that two such measurements, chosen at random, leave the remaining particles in a Bell state. These comparisons demonstrate not only that P-state entanglement is stronger than the other types but also that it is maximal in a well-defined sense. We prove that GHZ, cluster, and P states represent all possible entanglement classes of four-particle graph states with prime dā„3
General properties of quantum optical systems in a strong field limit
We investigate the dynamics of an arbitrary atomic system (n-level atoms or many n-level atoms) interacting with a resonant quantized mode of an em field. If the initial field state is a coherent state with a large photon number then the system dynamics possesses some general features, independently of the particular structure of the atomic system. Namely, trapping states, factorization of the wave function, collapses and revivals of the atomic energy oscillations are discussed
Cathodoluminescence studies of the electron injection-induced effects in GaN
Local irradiation of p-type GaN with the electron beam of a scanning electron microscope resulted in up to a threefold decrease of the peak cathodoluminescence intensity at similar to379 nm, as was observed in the variable temperature measurements. The cathodoluminescence results are consistent with an increase of the minority carrier diffusion length in the material, as is evident from the electron-beam-induced current measurements. The activation energy for the electron injection effect, estimated from the temperature-dependent cathodoluminescence, is in agreement with the thermal ionization energy of the Mg-acceptor in GaN
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