1. principles
  2. Dorky Poll: Quantum Pictures

Dorky Poll: Quantum Pictures

By drorzel on August 27, 2009.

I'm feeling slightly better, but still a little wobbly, so here's what may be the dorkiest Dorky Poll yet:

Tags
Physics
polls
Quantum Optics
Theory

More like this

What, no interaction picture?
Really, it all depends on the context. Probably Schrödinger for most things.

Dude! The interaction picture!!!!! Bare Hamiltonian evolves operators, interaction hamiltonian evolves state vectors.

Real answer? Whatevers easiest to use! The different pictures are different kinds of wrenches.

I second the inclusion of the interaction picture, but I would also say that insight is gained from a dozen or so other formalisms, e.g. Moyal-Wigner formalism, P/Q functions, your other favorite pseudo-probability formalism, path integrals, decoherence functionals, and a new formalism of my own devising that I haven't written up yet.

"Real answer? Whatevers easiest to use! The different pictures are different kinds of wrenches."

As a quantum foundationalist I would also say that they are also different shadows cast on the walls of Plato's cave by whatever truth that quantum theory is trying to tell us.

I prefer a timeless quantum or random field formalism. The state tells us the results of measurements wherever we make them in space and time. "States" are not a Lorentz invariant concept, insofar as they depend on a phase-space relative to a time-like hyperplane, so they are not appropriate for a manifestly Poincaré invariant presentation of a theory.

For example, I use a very natural manifestly LI formalism for quantum fields, in my "Equivalence of the Klein-Gordon random field and the complex Klein-Gordon quantum field", http://pantheon.yale.edu/~pwm22/Morgan-EPL-2009.pdf, which will appear shortly as EPL 87 (2009) 31002 (DOI: 10.1209/0295-5075/87/31002, to appear very soon, but it doesn't resolve at the time of writing). Sorry for the link, but it's the quickest way I have of showing you what the sort of formalism I prefer looks like.

I suppose those German mechanics are competent and thorough, and won't play tricks with their customers

I like retrodictive quantum mechanics, in which the state of the system is the measured state evolved backwards in time.

Well Matt, I think that quantum mechanics tells us that Plato's cave wall is all we got, and that only when we look!

For open systems, ones interacting with their environment, I love quantum trajectory theory!