BEGIN:VCALENDAR VERSION:2.0 PRODID:Data::ICal 0.22 BEGIN:VEVENT DESCRIPTION:Duff Neill\, Los Alamos National Lab\n\n
When learning about the properti es of a quantum mechanical system\, for instance\, the energy levels of it s bound states\, it is useful to think of the system as closed and isolate d from any environment\, though we know in any laboratory setting\, all sy stems eventually will interact with an environment. However\, we can often engineer such interactions to be weak\, short-ranged\, and controllable\, so that the isolated approximation is a good one.
\n\nI wi ll argue that in many physically relevant field theories\, the long-time o bservables or states of the theory can only be defined in the context of a quantum open system\, where we take into account the interactions between the system and the environment continually in the evolution of the system . This is because excitations of the field theory will inevitably create t heir own environment\, that is\, states we must trace over. Resumming thes e interactions with the self-created environment is necessary to give a co nvergent expansion for observables over all of phase-space.< /span>
\n DTSTART:20200122T203000Z LOCATION:Physics Building\, Room 204 SUMMARY:Quantum Open Systems and Field Theory END:VEVENT END:VCALENDAR