Mark Van Raamsdonk

University of British Columbia
Gravity and Information

Some of the grandest open questions in theoretical physics lie directly at the interface of quantum mechanics and gravity. How did our universe begin? How will it end? What is dark energy? What is inside a black hole? Fifteen years ago, researchers in string theory discovered a stunning connection between the physics of quantum gravity and the physics of quantum field theories, the well-understood mathematical models that physicists use to describe elementary particles and their interactions. Through this connection, known as the AdS/CFT correspondence, quantum gravity questions that were previously impossible to answer can be translated into much simpler questions that can be answered by quantum field theory. Recent work has suggested that a key to understanding how and why gravity emerges from the physics of these quantum field theories is to think about quantum field theory using methods from the emerging field of quantum information theory (the theory behind quantum computers). In my proposed research, I plan to use ideas from quantum information theory in the context of AdS/CFT to work towards a deeper understanding of spacetime, the nature of black holes, and the fundamental origin of gravitational forces.

The AdS/CFT correspondence in string theory gives a definition of certain theories of quantum gravity in terms of ordinary quantum field theory. Recent work has indicated the possibility that the most direct window into the gravitational physics comes by considering quantum information theoretic observables in the field theory. One interpretation is that spacetime represents a geometrical representation of the entanglement structure of the field theory state. This suggests a direct map between phenomena in quantum gravity and quantum information theory. The proposed research aims explore this connection, focusing on the following questions: Can we understand more precisely the emergence of a classical spacetime geometry from the quantum information in the state of a holographic field theory? Can we understand how properties of black holes (a hallmark feature of gravitational systems), specifically the trapping and very slow release of information, can emerge from a description in terms of ordinary quantum field theory? Can we understand the origin of gravitational attraction between generic objects from the dynamics of quantum information in the field theory? The answers to any of these questions would provide a deeper understand of how and why gravitational physics can emerge from ordinary quantum field theory.

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