### Overview

Quantum gravity; Quantum field theory; String theory; Black holes

### Research Focus

My research is on fundamental aspects of quantum gravity and quantum field theory, with a focus on black hole information and strongly interacting quantum fields. I use a variety of techniques from string theory, holographic duality, general relativity, and quantum information.

*Gauge/Gravity Duality*

Recent advances in string theory and quantum gravity suggest that spacetime, and the laws of gravity that govern it, are emergent phenomena resulting from the collective behavior of a large number of unknown degrees of freedom. This idea underlies gauge/gravity duality, which is an exact relation between quantum gravity and a lower-dimensional quantum field theory. One goal of my research is to understand how the degrees of freedom in a quantum field theory reorganize themselves into a fluctuating spacetime, and to use gauge/gravity duality as a model for a more complete theory of quantum gravity.

*Black Hole Information*

Black holes play an important role in quantum gravity because they can be viewed in two very different ways: as classical solutions of general relativity, or as quantum statistical systems obeying the laws of the thermodynamics. I am exploring this relationship in various contexts, including 3d gravity and more realistic Kerr black holes, by applying techniques from quantum information and statistical mechanics to problems in quantum gravity.

*New Approaches to Quantum Field Theory*

I am developing new methods to study strongly interacting quantum fields based on dualities, bootstrap techniques, and entanglement dynamics, with applications to critical phenomena, transport, and renormalization group flows.

*The Physics of de Sitter Space*

Ultimately, quantum gravity must be tested by experiment. There are two regimes of the known universe where quantum gravitational effects are large: black hole interiors and the very early universe. It is possible that fundamentally new ideas are needed to understand this regime, so I am working on new approaches to inflation and the physics of de Sitter space inspired by black hole information and gauge/gravity duality.

**Graduate Students**

Ryan Bilotta and Yikun Jiang

### Publications

J. Chandra, S. Collier, T. Hartman, A. Maloney, "Semiclassical 3D gravity as an average of large-c CFTs," JHEP 12 (2022) 069, arXiv:2203.06511.

A. Almheiri, T. Hartman, J. Maldacena, E. Shaghoulian, and A. Tajdini, "Replica wormholes and the entropy of Hawking radiation," JHEP05 (2020) 013, arXiv:1911.12333

T. Hartman, D. Mazac, and L. Rastelli, "Sphere Packing and Quantum Gravity," JHEP 2019:48, arXiv:1905.01319.

T. Hartman, S. Jain, S. Kundu, “Causality Constraints in Conformal Field Theory,” JHEP 2016:99, arXiv: 1509.00014.

T. Faulkner, M. Guica, T. Hartman, R. C. Myers, M. Van Raamsdonk, “Gravitation from Entanglement in Holographic CFTs,” JHEP **1403 **(2014) 051 arXiv: 1312.7856.

T. Hartman, J. Maldacena, “Time Evolution of Entanglement Entropy from Black Hole Interiors,” JHEP **1305** (2013) 014 arXiv: 1303.1080.

M. Guica, T. Hartman, W. Song, A. Strominger, “The Kerr/CFT Correspondence,” Phys. Rev. D**80** (2009) 124008 arXiv:0809:4266 [hep-th].

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