Equilibration of Isolated Macroscopic Quantum Systems under Experimentally Realistic Conditions

Understand

In how far does an non-equilibrium initial ensemble evolve towards a stationary long time behavior for an isolated macroscopic quantum system? We demonstrate that deviations from a steady state indeed become unmeasurably small or exceedingly rare after initial transients have died out under the following conditions: The Hamilonian does not exhibit exceedingly large degeneracies of energy eigenvalues and energy gaps.

• A large number of energy levels is significantly populated by the initial ensemble.
• The system is observed by a measurement device with a reasonably bound working range compared to the resolution limit.
• The entire experiment, ending with the quantum mechanical measurement process, can only be repeated a "reasonable" number of times.