In quantum information technology, it is crucial to be able to generate signals on demand in order to describe transfer of information. Such states must be locally equivalent to some background state outside the light cone of the trigger. It is of interest both to understand this equivalence, and more fundamentally, to understand local operations and measurements in quantum field theory (QFT).
Possible master's thesis topics include:
Local measurements and operations in QFT. What exactly are local measurements and quantum operations in QFT? What is the state-update rule post measurement in QFT? How to settle Sorkin's scenario?
Local equivalence: two states are said to be locally equivalent in X, if they predict the same measurement statistics for all local measurements in X. Develop the theory of equivalence for (possibly mixed) states, and consider the relation to explicitly time-dependent processes.
For both topics the work will involve mathematical analysis (pen-and-paper), possibly with some analytical computer tools and/or numerics.