11,168 research outputs found
Code properties from holographic geometries
Almheiri, Dong, and Harlow [arXiv:1411.7041] proposed a highly illuminating
connection between the AdS/CFT holographic correspondence and operator algebra
quantum error correction (OAQEC). Here we explore this connection further. We
derive some general results about OAQEC, as well as results that apply
specifically to quantum codes which admit a holographic interpretation. We
introduce a new quantity called `price', which characterizes the support of a
protected logical system, and find constraints on the price and the distance
for logical subalgebras of quantum codes. We show that holographic codes
defined on bulk manifolds with asymptotically negative curvature exhibit
`uberholography', meaning that a bulk logical algebra can be supported on a
boundary region with a fractal structure. We argue that, for holographic codes
defined on bulk manifolds with asymptotically flat or positive curvature, the
boundary physics must be highly nonlocal, an observation with potential
implications for black holes and for quantum gravity in AdS space at distance
scales small compared to the AdS curvature radius.Comment: 17 pages, 5 figure
The WISDOM Radar: Unveiling the Subsurface Beneath the ExoMars Rover and Identifying the Best Locations for Drilling
The search for evidence of past or present life on Mars is the principal objective of the 2020 ESA-Roscosmos ExoMars Rover mission. If such evidence is to be found anywhere, it will most likely be in the subsurface, where organic molecules are shielded from the destructive effects of ionizing radiation and atmospheric oxidants. For this reason, the ExoMars Rover mission has been optimized to investigate the subsurface to identify, understand, and sample those locations where conditions for the preservation of evidence of past life are most likely to be found. The Water Ice Subsurface Deposit Observation on Mars (WISDOM) ground-penetrating radar has been designed to provide information about the nature of the shallow subsurface over depth ranging from 3 to 10 m (with a vertical resolution of up to 3 cm), depending on the dielectric properties of the regolith. This depth range is critical to understanding the geologic evolution stratigraphy and distribution and state of subsurface H2O, which provide important clues in the search for life and the identification of optimal drilling sites for investigation and sampling by the Rover's 2-m drill. WISDOM will help ensure the safety and success of drilling operations by identification of potential hazards that might interfere with retrieval of subsurface samples
Calogero-Sutherland Approach to Defect Blocks
Extended objects such as line or surface operators, interfaces or boundaries
play an important role in conformal field theory. Here we propose a systematic
approach to the relevant conformal blocks which are argued to coincide with the
wave functions of an integrable multi-particle Calogero-Sutherland problem.
This generalizes a recent observation in 1602.01858 and makes extensive
mathematical results from the modern theory of multi-variable hypergeometric
functions available for studies of conformal defects. Applications range from
several new relations with scalar four-point blocks to a Euclidean inversion
formula for defect correlators.Comment: v2: changes for clarit
Holographic Entanglement Entropy
We review the developments in the past decade on holographic entanglement
entropy, a subject that has garnered much attention owing to its potential to
teach us about the emergence of spacetime in holography. We provide an
introduction to the concept of entanglement entropy in quantum field theories,
review the holographic proposals for computing the same, providing some
justification for where these proposals arise from in the first two parts. The
final part addresses recent developments linking entanglement and geometry. We
provide an overview of the various arguments and technical developments that
teach us how to use field theory entanglement to detect geometry. Our
discussion is by design eclectic; we have chosen to focus on developments that
appear to us most promising for further insights into the holographic map.
This is a draft of a few chapters of a book which will appear sometime in the
near future, to be published by Springer. The book in addition contains a
discussion of application of holographic ideas to computation of entanglement
entropy in strongly coupled field theories, and discussion of tensor networks
and holography, which we have chosen to exclude from the current manuscript.Comment: 154 pages. many figures. preliminary version of book chapters.
comments welcome. v2: typos fixed and references adde
Local fields in boundary conformal QFT
Conformal field theory on the half-space x>0 of Minkowski space-time
("boundary CFT") is analyzed from an algebraic point of view, clarifying in
particular the algebraic structure of local algebras and the bi-localized
charge structure of local fields. The field content and the admissible boundary
conditions are characterized in terms of a non-local chiral field algebra.Comment: 58 pages, 5 figures. v2: organization of results improved; version to
appear in RM
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