Covariant Phase-Space Representation for Harmonic Oscillators

S. Twareque Ali, Eduard Prugovečki

Y. S. Kim, Eugene Paul Wigner

It is shown that, in the phase-space representation of quantum mechanics, the uncertainty relation can be stated in terms of the integral invariant of Poincar\'e. The uncertainty relation for spreading free wave packets is discussed as an illustrative example. This phase-space approach can be extended to the relativistic regime. It is shown that Lorentz boosts are area-preserving canonical transformations in the phase space of the light-cone variables. The harmonic oscillator is discussed in detail as an illustrative example for the covariant realization of the uncertainty principle.

Weixuan Hu

Covariant phase space quantization attempts to quantize the full space of classical solutions, leading to a quantum theory in which the usual time coordinate is missing. In this paper we explore how the time evolution of the quantum states of this system is restored. We compare covariant phase space methods for a nonrelativistic system (the harmonic oscillator) and three relativistic quantum cosmologies. We find that for the nonrelativistic case the preferred time coordinate emerges in a phase factor when one transforms among certain representations, giving exactly the phase that appears when the time evolution operator acts on the stationary states in the usual quantization method. For the relativistic cases, on the other hand, this phase factor is no longer present, and covariance appears to be restored. These results are consistent with other quantization methods for these models.

Y. S. Kim, Marilyn E. Noz

Suzana Bedić, Otto C. W. Kong, Hock King Ting

We present the formulation of a version of Lorentz covariant quantum mechanics based on a group theoretical construction from a Heisenberg–Weyl symmetry with position and momentum operators transforming as Minkowski four-vectors. The basic representation is identified as a coherent state representation, essentially an irreducible component of the regular representation, with the matching representation of an extension of the group C*-algebra giving the algebra of observables. The key feature is that it is not unitary but pseudo-unitary, exactly in the same sense as the Minkowski spacetime representation. The language of pseudo-Hermitian quantum mechanics is adopted for a clear illustration of the aspect, with a metric operator obtained as really the manifestation of the Minkowski metric on the space of the state vectors. Explicit wavefunction description is given without any restriction of the variable domains, yet with a finite integral inner product. The associated covariant harmonic oscillator Fock state basis has all the standard properties in exact analog to those of a harmonic oscillator with Euclidean position and momentum operators. Galilean limit and the classical limit are retrieved rigorously through appropriate symmetry contractions of the algebra and its representation, including the dynamics described through the symmetry of the phase space.