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On the cardinality of complex matrix scalings

George Hutchinson (2016)

Special Matrices

We disprove a conjecture made by Rajesh Pereira and Joanna Boneng regarding the upper bound on the number of doubly quasi-stochastic scalings of an n × n positive definite matrix. In doing so, we arrive at the true upper bound for 3 × 3 real matrices, and demonstrate that there is no such bound when n ≥ 4.

On the curvature of the space of qubits

Attila Andai (2006)

Banach Center Publications

The Fisher informational metric is unique in some sense (it is the only Markovian monotone distance) in the classical case. A family of Riemannian metrics is called monotone if its members are decreasing under stochastic mappings. These are the metrics to play the role of Fisher metric in the quantum case. Monotone metrics can be labeled by special operator monotone functions, according to Petz's Classification Theorem. The aim of this paper is to present an idea how one can narrow the set of monotone...

On the Lebesgue decomposition of the normal states of a JBW-algebra

Jacques Dubois, Brahim Hadjou (1992)

Mathematica Bohemica

In this article, a theorem is proved asserting that any linear functional defined on a JBW-algebra admits a Lebesque decomposition with respect to any normal state defined on the algebra. Then we show that the positivity (and the unicity) of this decomposition is insured for the trace states defined on the algebra. In fact, this property can be used to give a new characterization of the trace states amoungst all the normal states.

On the quantal nature of the Coulomb field

Andrzej Staruszkiewicz (1997)

Banach Center Publications

It is shown that the total electric charge, as determined from the Gauss law, is a quantum object. The argument is based on elementary considerations concerning the number of photons, which should be large in a classical situation.

On the set representation of an orthomodular poset

John Harding, Pavel Pták (2001)

Colloquium Mathematicae

Let P be an orthomodular poset and let B be a Boolean subalgebra of P. A mapping s:P → ⟨0,1⟩ is said to be a centrally additive B-state if it is order preserving, satisfies s(a') = 1 - s(a), is additive on couples that contain a central element, and restricts to a state on B. It is shown that, for any Boolean subalgebra B of P, P has an abundance of two-valued centrally additive B-states. This answers positively a question raised in [13, Open question, p. 13]. As a consequence one obtains a somewhat...

On the state complexity of semi-quantum finite automata

Shenggen Zheng, Jozef Gruska, Daowen Qiu (2014)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

Some of the most interesting and important results concerning quantum finite automata are those showing that they can recognize certain languages with (much) less resources than corresponding classical finite automata. This paper shows three results of such a type that are stronger in some sense than other ones because (a) they deal with models of quantum finite automata with very little quantumness (so-called semi-quantum one- and two-way finite automata); (b) differences, even comparing with probabilistic...

On the structure of numerical event spaces

Gerhard Dorfer, Dietmar W. Dorninger, Helmut Länger (2010)

Kybernetika

The probability p ( s ) of the occurrence of an event pertaining to a physical system which is observed in different states s determines a function p from the set S of states of the system to [ 0 , 1 ] . The function p is called a numerical event or multidimensional probability. When appropriately structured, sets P of numerical events form so-called algebras of S -probabilities. Their main feature is that they are orthomodular partially ordered sets of functions p with an inherent full set of states. A classical...

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