Doctoral defence in Physics - Juan Fernando Angel Ramelli

Live stream:https://www.youtube.com/user/HIvarp/live

Ph.D. student: Juan Fernando Angel Ramelli

Dissertation title: Entanglement in Quantum Lifshitz Theories

Opponents: 
Dr. Stefan Vandoren, Professor at Utrecht University, The Netherlands.
Dr. Jens Hjörleifur Bárðarson, Associate Professor at KTH Royal Institute of Technology, Sweden

Advisor: Dr. Valentina Giangreco Puletti, Professor at the Faculty of Physical Sciences, University of Iceland 

Doctoral committee: 

Dr. Lárus Thorlacius, Professor at the Faculty of Physical Sciences, University of Iceland
Dr. Þórður Jónsson, Professor at the Faculty of Physical Sciences, University of Iceland
Dr. Erik Tonni, Associate Professor at SISSA, Italy.

Chair of Ceremony: Dr. Einar Örn Sveinbjörnsson, Professor and the Head of the Faculty of Physical Sciences, University of Iceland

Abstract:
In recent years, the study of entanglement properties of quantum field theories has led to deep insights in fields as diverse as quantum gravity and condensed matter physics. Originating as effective field theories for certain quantum dimer models, the Quantum Lifshitz Model (QLM) and its generalizations are bosonic quantum field theories with anisotropic scaling symmetry between space and time. Being closely related to conformal field theories, they provide a fruitful playground, where diverse entanglement calculations can be performed analytically.

In this thesis, we concentrate on two entanglement measures, the entanglement entropy and logarithmic negativity. Motivated to extract subleading universal behavior, we perform analytic calculations in two and higher even dimensions. In order to make the calculations tractable, we put the QLM on compact manifolds, such as spheres and tori, where the spectrum of a certain operator appearing in the ground state of the theory is explicitly known. Mostly by means of the replica method, we then find analytic expressions for the finite subleading terms of the entanglement entropy and logarithmic negativity of the ground state, as well as the entanglement entropy of the excited states of the QLM. In the case of the ground state entanglement entropy, we provide analytic expressions for the sub-leading terms as functions of the dimension and the dynamical critical exponent. For the excited states we provide analytic formulae of the sub-leading coefficients as functions of the excitation numbers.

About the doctoral candidate
Juan Fernando Angel Ramelli was born in Bogotá, Colombia in 1990. He moved to Switzerland in 2001 where he obtained his high school diploma with an emphasis in mathematics and physics in 2009. He then enrolled at the Swiss Federal Institute of Technology (ETH) in Zürich to study physics, where he received a Bachelor’s degree in 2013 and finally a Master’s degree in theoretical physics in 2015. In 2016, he moved to Iceland to pursue his PhD.