How to gauge general quantum processes?

How to gauge general quantum processes?

Seminar author:Cristina Cirstoiu

Event date and time:10/16/2017 04:00:pm

Event location:Seminar Room

Event contact:

Gauge theories are fundamental in our understanding of the laws of nature. The formalism emerges from the concept of symmetry and exploits redundant degrees of freedom. One can easily gauge Lagrangians by extending the global invariance to a local one at the expense of introducing gauge fields with suitable transformation properties. More recently in the context of many body theory it has been shown how to gauge pure quantum states. How can we gauge general quantum processes? In this talk we describe a novel quantum information perspective on gauge theories that gives a method to gauge dynamics beyond the Lagrangian or Hamiltonian formalisms. More generally we explore what is the structure of quantum channels on composite systems under global symmetry constraints. We show they admit an essentially unique decomposition in terms of symmetry breaking degrees of freedom between the subsystems. This framework allows to draw a connection between Gauss’s law and resource theories and moreover to view gauge theories through the lens of reference frames. The setting of resource theories has been fruitful to explore entanglement which does not readily admit a Lagrangian description and therefore our framework could be of interest in studying entanglement in gauge theories.