On a Probabilistic Characterization of Hilbert Space

Ahmed Hasan

Luigi Accardi

Andrei Yu. Khrennikov

Andrei Yu. Khrennikov

In this chapter contextual probabilistic entanglement is represented withinthe Hilbert space formalism. The notion of entanglement is clarified anddemystified through decoupling it from the tensor product structure andtreating it as a constraint posed by probabilistic dependence of quantum observablesA and B. In this framework, it is meaningless to speak aboutentanglement without pointing to the fixed observables A and B, so thisis AB-entanglement. Dependence of quantum observables is formalized asnon-coincidence of conditional probabilities. Starting with this probabilisticdefinition, we achieve the Hilbert space characterization of the AB-entangledstates as amplitude non-factorisable states. In the tensor productcase, AB-entanglement implies standard entanglement, but not vice versa.AB-entanglement for dichotomous observables is equivalent to their correlation. Finally, observables entanglement is compared with dependence of random variables in classical probability theory.

Andrei Yu. Khrennikov

We study the problem of consistency of classical and quantum probabilistic models (also known as the problem of existence of hidden variables). We show that the solution of this problem depends crucially on a mathematical model for correspondence between classical (“prequantum”) model and quantum model. We construct a projection of the classical measure theoretic model to the complex Hilbert space, which shares the distinguishing features of the quantum model: interference of probabilities, Born's rule, complex probabilistic amplitudes, Hilbert state space, representation of observables by operators. These structures are present in a latent form in the classical Kolmogorov probability model. However, the classical model should be considered as a calculus of contextual probabilities. We constructed the representation of contextual probabilistic dynamics in the complex Hilbert space. Thus dynamics of the wave function can be considered as Hilbert space projections of realistic dynamics in a “prespace”. The basic condition for representing the prespace dynamics is the law of statistical conservation of energy—conservation of probabilities. In general, the Hilbert space projection of the “prespace” dynamics can be nonlinear and even irreversible (but it is always unitary).

Stanley Gudder