Josiah Couch, UT-Austin

"Studies in Holographic Complexity"

Abstract: This dissertation will present the work I have done on the conjectured relationship between various bulk quantities designed to capture the growth of the wormhole in eternal black hole spacetimes and the circuit complexity of the boundary state within the context of the AdS/CFT correspondence, i.e., on the topic of 'holographic complexity.' Four papers are presented here, each focused on the bulk side of this proposed relationship. In these papers, my various co-authors and I seek to improve our understanding of the bulk quantities in question (action of a causal diamond, maximal volume) and test the internal consistency of these proposals and their consistency with our intuition and understanding of the boundary field theory. In particular, the first of these papers focuses on properties of maximal volume slices in black hole spacetimes, along with consequences for the 'complexity = volume' conjecture. The next paper considers whether 'complexity = action' is consistent with the intuition we develop about the time evolution of the boundary circuit complexity in space-times dual to non-commutative field theories. The third paper deals with a possible relationship between the rate of increase of complexity and the thermodynamic volume of black hole spacetimes. Finally, the last paper deals with restrictions of the 'complexity = action' and 'complexity = volume' conjectures to boundary subregions and their corresponding entanglement wedges and seeks to test the consistency of a conjecture relating these restrictions to the purification complexity of the reduced density matrix.