Minimal Position-Velocity Uncertainty Wave Packets in Relativistic and Non-relativistic Quantum Mechanics

Jul, 2009
32 pages
Published in:
  • Annals Phys. 324 (2009) 2599-2621
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Abstract: (arXiv)
We consider wave packets of free particles with a general energy-momentum dispersion relation E(p)E(p). The spreading of the wave packet is determined by the velocity v = \p_p E. The position-velocity uncertainty relation \Delta x \Delta v \geq {1/2} |< \p_p^2 E >| is saturated by minimal uncertainty wave packets Φ(p)=Aexp(αE(p)+βp)\Phi(p) = A \exp(- \alpha E(p) + \beta p). In addition to the standard minimal Gaussian wave packets corresponding to the non-relativistic dispersion relation E(p)=p2/2mE(p) = p^2/2m, analytic calculations are presented for the spreading of wave packets with minimal position-velocity uncertainty product for the lattice dispersion relation E(p)=cos(pa)/ma2E(p) = - \cos(p a)/m a^2 as well as for the relativistic dispersion relation E(p)=p2+m2E(p) = \sqrt{p^2 + m^2}. The boost properties of moving relativistic wave packets as well as the propagation of wave packets in an expanding Universe are also discussed.