scholarly journals Geometric quantum information structure in quantum fields and their lattice simulation

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
Natalie Klco ◽  
Martin J. Savage
Keyword(s):  
Quantum Information ◽  
Information Structure ◽  
Quantum Fields ◽  
Lattice Simulation

scholarly journals Quantum information processing and relativistic quantum fields

2014 ◽  
Vol 31 (7) ◽  
pp. 075007 ◽  
Author(s):  
Dionigi M T Benincasa ◽  
Leron Borsten ◽  
Michel Buck ◽  
Fay Dowker
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Relativistic Quantum ◽  
Quantum Fields

scholarly journals Effective entropy of quantum fields coupled with gravity

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Xi Dong ◽  
Xiao-Liang Qi ◽  
Zhou Shangnan ◽  
Zhenbin Yang
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Quantum Information ◽  
Entanglement Entropy ◽  
Closed Universe ◽  
Quantum Field ◽  
Quantum Fields ◽  
Extremal Surface ◽  
Tensor Network ◽  
Random Tensor

Abstract Entanglement entropy, or von Neumann entropy, quantifies the amount of uncertainty of a quantum state. For quantum fields in curved space, entanglement entropy of the quantum field theory degrees of freedom is well-defined for a fixed background geometry. In this paper, we propose a generalization of the quantum field theory entanglement entropy by including dynamical gravity. The generalized quantity named effective entropy, and its Renyi entropy generalizations, are defined by analytic continuation of a replica calculation. The replicated theory is defined as a gravitational path integral with multiple copies of the original boundary conditions, with a co-dimension-2 brane at the boundary of region we are studying. We discuss different approaches to define the region in a gauge invariant way, and show that the effective entropy satisfies the quantum extremal surface formula. When the quantum fields carry a significant amount of entanglement, the quantum extremal surface can have a topology transition, after which an entanglement island region appears. Our result generalizes the Hubeny-Rangamani-Takayanagi formula of holographic entropy (with quantum corrections) to general geometries without asymptotic AdS boundary, and provides a more solid framework for addressing problems such as the Page curve of evaporating black holes in asymptotic flat spacetime. We apply the formula to two example systems, a closed two-dimensional universe and a four-dimensional maximally extended Schwarzchild black hole. We discuss the analog of the effective entropy in random tensor network models, which provides more concrete understanding of quantum information properties in general dynamical geometries. We show that, in absence of a large boundary like in AdS space case, it is essential to introduce ancilla that couples to the original system, in order for correctly characterizing quantum states and correlation functions in the random tensor network. Using the superdensity operator formalism, we study the system with ancilla and show how quantum information in the entanglement island can be reconstructed in a state-dependent and observer-dependent map. We study the closed universe (without spatial boundary) case and discuss how it is related to open universe.

scholarly journals Transmission of quantum information through quantum fields

2020 ◽  
Vol 101 (3) ◽  
Author(s):  
Petar Simidzija ◽  
Aida Ahmadzadegan ◽  
Achim Kempf ◽  
Eduardo Martín-Martínez
Keyword(s):  
Quantum Information ◽  
Quantum Fields

Simple quantum information algorithms in cavity QED

2003 ◽  
Vol 50 (6-7) ◽  
pp. 901-913 ◽  
Author(s):  
H. Ollivier ◽  
F. Yamaguchi ◽  
M. Brune ◽  
J. M. Raimond ◽  
S. Haroche ◽  
...  
Keyword(s):  
Quantum Information ◽  
Cavity Qed ◽  
Simple Quantum

A Political Economy Model of a Research University

2009 ◽  
pp. 132-143
Author(s):  
K. Sonin ◽  
I. Khovanskaya
Keyword(s):  
Organizational Structure ◽  
Information Structure ◽  
Research University ◽  
Hiring Decisions ◽  
Voting Rules ◽  
Economy Model ◽  
Trade Offs ◽  
Political Economic ◽  
Optimal Incentives

Hiring decisions are typically made by committees members of which have different capacity to estimate the quality of candidates. Organizational structure and voting rules in the committees determine the incentives and strategies of applicants; thus, construction of a modern university requires a political structure that provides committee members and applicants with optimal incentives. The existing political-economic model of informative voting typically lacks any degree of variance in the organizational structure, while political-economic models of organization typically assume a parsimonious information structure. In this paper, we propose a simple framework to analyze trade-offs in optimal subdivision of universities into departments and subdepartments, and allocation of political power.

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