Finite-Dimensional State Spaces

Norman Goldstein

Joe Mashburn

In 2002 Coecke and Martin created a Bayesian order for the finite dimensional spaces of classical states in physics and used this to define a similar order, the spectral order on the finite dimensional quantum states. These orders gave the spaces a structure similar to that of a domain. This allows for measuring information content of states and for determining which partial states are approximations of which pure states. In a previous paper the author extended the Bayesian order to infinite dimensional spaces of classical states. The order on infinite dimensional spaces retains many of the characteristics important to physics, but loses the domain theoretic structure. It becomes impossible to measure information content in the same way that it is done for the finite dimensional spaces, and the sense of approximation is lost. In this paper, we will use the Bayesian order to define a spectral order on the infinite dimensional spaces of quantum states.

Viktor Holubec

Adam Miranowicz, W. Leoński, Nobuyuki Imoto

This chapter presents two essentially different constructions of harmonic oscillator states in a finite-dimensional (FD) Hilbert space. The authors propose some new definitions of the states and find their explicit forms in the Fock representation. For the convenience of the reader, they bring together several known FD quantum-optical states, including FD coherent states, FD phase coherent states, FD displaced number states, FD Schrödinger cats, and FD squeezed vacuums. The discrete Wigner function is applied in order to demonstrate intriguing properties of the various states.

Armin Uhlmann, Bernd Crell

Yong Zhang

The energy level structure of the q deformed harmonic oscillator in a finite dimensional Hilbert space is studied.The Coherent states of the q deformed harmonic oscillator in a finite dimensional Hilbert space are constructed.It is shown that the energy level structure and the dynamic action are very different from that of usual harmonic oscillator due to the finiteness of the dimension of Hilbert space and the deformation parameter′s influence,and the coherent states are different from the Glauber coherent states.