Holographic entanglement entropy of surface defects

We calculate the holographic entanglement entropy in type IIB supergravity solutions that are dual to half-BPS disorder-type surface defects in ${\cal N}=4$ Super Yang-Mills theory. The entanglement entropy is calculated for a ball-shaped region bisected by a surface defect. Using the bubbling supergravity solutions we also compute the expectation value of the defect operator. Combining our result with the previously-calculated one-point function of the stress tensor in the presence of the defect, we adapt the calculation of Lewkowycz and Maldacena to obtain a second expression for the entanglement entropy. Our two expressions agree up to an additional term, whose possible origin and significance is discussedComment: 41 pages. pdflatex, 3 figures. v2: typos corrected, reference corrected, some comments on CFT interpretation added. v3: references added, some clarification

Entanglement entropy vs. free energy in IIB supergravity duals for 5d SCFTs

We study entanglement entropy and the free energy in recently constructed holographic duals for 5d SCFTs in type IIB supergravity. The solutions exhibit mild singularities, which could potentially complicate holographic applications. We use the relation of the entanglement entropy for a spherical entangling surface to the free energy of the field theory on the five sphere as a well-motivated benchmark to assess how problematic the singularities are. The holographic supergravity computations give well-defined results for both quantities and they satisfy the expected relations. This supports the interpretation of the solutions as holographic duals for 5d SCFTs and gives first quantitative indications for the nature of the dual SCFTs.Comment: 25 pages, 3 figure

The law of activity delays

Delays in activities completion drive human projects to schedule and cost overruns. It is believed activity delays are the consequence of multiple idiosyncrasies without specific patterns or rules. Here we show that is not the case. Using data for 180 construction project schedules, we demonstrate that activity delays satisfy a universal model that we call the law of activity delays. After we correct for delay risk factors, what remains follows a log-normal distribution.Comment: 7 pages, 4 figures, 1 tabl

Entanglement entropy of Wilson surfaces from bubbling geometries in M-theory

We consider solutions of eleven-dimensional supergravity constructed in [1,2] that are half-BPS, locally asymptotic to $AdS_7\times S^4$ and are the holographic dual of heavy Wilson surfaces in the six-dimensional $(2,0)$ theory. Using these bubbling solutions we calculate the holographic entanglement entropy for a spherical entangling surface in the presence of a planar Wilson surface. In addition, we calculate the holographic stress tensor and, by evaluating the on-shell supergravity action, the expectation value of the Wilson surface operator.Comment: 42 pages, 4 figures, v2: minor modification

Holographic Entanglement Entropy in the Presence of Defects

A quantum observable which received renewed attention recently is entanglement entropy. It's application ranges over several fields in physics, from condensed matter physics to general relativity. In this dissertation we study entanglement entropy for quantum field theories in the presence of defects and singularities. We study entanglement entropy using the framework of AdS/CFT correspondence. We focus on entangling surfaces across ball-shaped regions for systems outside their ground state. Quantum field theories in the presence of defects are considered first. These are the six-dimensional $(2,0)$ theory in the presence of Wilson surfaces and the four-dimensional \cN = 4 super-Yang-Mills theory in the presence of surface defects of the disordered type. Their holographic entanglement entropy is calculated applying the Ryu-Takayanagi prescripstion on their holographic duals, which are eleven-dimensional supergravity (M-theory) solutions for the former and ten-dimensional type IIB supergravity solutions for the latter. Other holographic observables are computed as well: the holographic stress tensor and the expectation value of the defect (operator). For the disordered defects, an alternative expression for the additional entanglement entropy due to the defect (in terms of expectation values) is derived, adapting the method of Lewkowycz and Maldacena for Wilson loops. The two entanglement entropies agree up to an additional term, the origin of which may be attributed to the conformal anomaly of even dimensional defects as we discuss. The holographic entanglement and free energy is computed for five-dimensional super conformal field theories, starting from their holographic supergravity duals. Although the supergravity solutions possess singularities, these do not obstruct our calculations. The expected relation between the two observables is verified. This supports the supergravity solutions as holographic duals and gives the first quantitative results for five-dimensional superconformal field theories

Holographic entanglement entropy of surface defects

We calculate the holographic entanglement entropy in type IIB supergravity solutions that are dual to half-BPS disorder-type surface defects in ${\cal N}=4$ Super Yang-Mills theory. The entanglement entropy is calculated for a ball-shaped region bisected by a surface defect. Using the bubbling supergravity solutions we also compute the expectation value of the defect operator. Combining our result with the previously-calculated one-point function of the stress tensor in the presence of the defect, we adapt the calculation of Lewkowycz and Maldacena to obtain a second expression for the entanglement entropy. Our two expressions agree up to an additional term, whose possible origin and significance is discusse