Symplectic coarse-grained dynamics: Chalkboard motion in classical and quantum mechanics

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 Schrödinger). 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.

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This work has been supported by the Grants P23902-N13 and P27773-N25 of the Austrian Research Foundation FWF.

Published 2 September 2020