On the notion of Weyl system

Maurice A. de Gosson

The notion of phase plays an esential role in both classical and quantum mechanics.But what is a phase? We show that if we define the notion of phase in phase (!) space one can very easily and naturally recover the Heisenberg-Weyl formalism; this is achieved using the properties of the Poincare-Cartan invariant, and without making any quantum assumption.

Maurice A. de Gosson

Diego Lucio Rapoport

We review the relation between space-time geometries with torsion fields (the so-called Riemann-Cartan-Weyl (RCW) )geometries) and their associated Brownian motions. In this setting, the metric conjugate of the tracetorsion one-form is the drift vectorfield of the Brownian motions. Thus, in the present approach, Brownian motions, in distinction with Nelson�s Stochastic Mechanics, are spacetime structures. We extend this to the state-space of non-relativistic quantum mechanics and discuss the relation between a noncanonical quantum RCW geometry in state-space associated with the gradient of the quantum-mechanical expectation value of a self-adjoint operator given by the generalized laplacian operator defined by a RCW geometry. We discuss the reduction of the wave function in terms of a RCW quantum geometry in state-space. We characterize the Schroedinger equation for both an observed and unobserved quantum systems in terms of the RCW geometries and Brownian motions. Thus, in this work, the Schroedinger field is a torsion generating field, and the U and R processes, in the sense of Penrose, are associated, the former to spacetime geometries and their associated Brownian motions, and the latter to their extension to the state-space of nonrelativistic quantum mechanics given by the projective Hilbert space. In this setting, the Schroedinger equation can be either linear or nonlinear. We discuss the problem of the many times variables and the relation with dissipative processes. We present as an additional example of RCW geometries and their Brownian motions counterpart, the dynamics of viscous fluids obeying the invariant Navier-Stokes equations. We introduce in the present setting an extension of R. Kiehn�s approach to dynamical systems starting from the notion of the topological dimension of one-forms, to apply it to the trace-torsion one-form whose metric conjugate is the Brownian motion�s drift vectorfield and discuss the topological notion of turbulence. We discuss the relation between our setting and the Nottale theory of Scale Relativity, and the work of Castro and Mahecha in this volume in nonlinear quantum mechanics, Weyl geometries and the quantum potential.

N. Mukunda, G. Marmo, A. Zampini +2 more

The Wigner–Weyl isomorphism for quantum mechanics on a compact simple Lie group G is developed in detail. Several features are shown to arise which have no counterparts in the familiar Cartesian case. Notable among these is the notion of a semiquantized phase space, a structure on which the Weyl symbols of operators turn out to be naturally defined and, figuratively speaking, located midway between the classical phase space T*G and the Hilbert space of square integrable functions on G. General expressions for the star product for Weyl symbols are presented and explicitly worked out for the angle-angular momentum case.

Maurice A. de Gosson