# Symplectic Coarse-Grained Dynamics: Chalkboard Motion in Classical and Quantum Mechanics

## TL;DR

This paper introduces a novel approach to classical and quantum mechanics by focusing on the evolution of phase space ellipsoids with preserved symplectic capacity, enabling new ways to guide and control system dynamics.

## Contribution

It proposes reversing traditional paradigms by studying motions of phase space ellipsoids instead of points, linking classical coarse graining and quantum blobs through symplectic geometry.

## Key findings

- Ellipsoids preserve symplectic capacity during motion.
- Classical phase space coarse graining is linked to quantum blobs.
- New methods for guiding phase space motions are demonstrated.

## Abstract

In the usual approaches to mechanics (classical or quantum) the primary object of interest is the Hamiltonian, from which one tries to deduce the solutions of the equations of motion (Hamilton or Schr\"odinger). In the present work we reverse this paradigm and view the motions themselves as being the primary objects. This is made possible by studying arbitrary phase space motions, not of points, but of (small) ellipsoids with the requirement that the symplectic capacity of these ellipsoids is preserved. This allows us to guide and control these motions as we like. In the classical case these ellipsoids correspond to a symplectic coarse graining of phase space, and in the quantum case they correspond to the "quantum blobs" we defined in previous work, and which can be viewed as minimum uncertainty phase space cells which are in a one-to-one correspondence with Gaussian pure states.