Theory Seminar: Dissipative phase transitions and passive error correction

Simon Lieu (JQI Maryland)
Quantum phase transitions come in a variety of flavors, including symmetry-breaking transitions and symmetry-protected topological transitions.

Simon Lieu (JQI Maryland)
Group Seminar via Zoom
Wed 3. November 2021, 15:30 pm (MEZ)

Abstract:

Quantum phase transitions come in a variety of flavors, including symmetry-breaking transitions and symmetry-protected topological transitions. While these paradigms are by now well understood for closed systems, their generalization to dissipative open systems remains less thoroughly explored. In this talk, I will describe some recent progress in this direction. This task has practical relevance: A non-trivial phase can be characterized by an emergent steady state degeneracy in the thermodynamic limit, which is the key ingredient for "passive" quantum error correction. I will describe photonic cat codes in the language of symmetry breaking transitions, and show that error correcting properties are related to the model's phase diagram. I will also describe a theory of symmetry-protected topological edge modes in open band insulators, and discuss challenges related to stabilizing quantum information in the steady state of such systems. Finally, I will comment on the role of time-reversal symmetry in dissipative systems by presenting a generalization of Kramers' degeneracy for Markovian dynamics.

If you'd like to participate in the seminar, please contact us!