scholarly journals Entanglement negativity after a local quantum quench in conformal field theories

2015 ◽  
Vol 92 (7) ◽  
Author(s):  
Xueda Wen ◽  
Po-Yao Chang ◽  
Shinsei Ryu
Keyword(s):  
Field Theories ◽  
Conformal Field Theories ◽  
Conformal Field ◽  
Quantum Quench ◽  
Local Quantum

scholarly journals ENTANGLEMENT ENTROPY FROM SURFACE TERMS IN GENERAL RELATIVITY

2013 ◽  
Vol 22 (12) ◽  
pp. 1342020 ◽  
Author(s):  
ARPAN BHATTACHARYYA ◽  
ANINDA SINHA
Keyword(s):  
General Relativity ◽  
Entanglement Entropy ◽  
Field Theories ◽  
Quantum Field Theories ◽  
Conformal Field Theories ◽  
Btz Black Hole ◽  
Conformal Field ◽  
Local Quantum ◽  
Gauge Gravity ◽  
Gravity Duality

Entanglement entropy in local quantum field theories is typically ultraviolet divergent due to short distance effects in the neighborhood of the entangling region. In the context of gauge/gravity duality, we show that surface terms in general relativity are able to capture this entanglement entropy. In particular, we demonstrate that for 1 + 1-dimensional (1 + 1d) conformal field theories (CFTs) at finite temperature whose gravity dual is Banados–Teitelboim–Zanelli (BTZ) black hole, the Gibbons–Hawking–York term precisely reproduces the entanglement entropy which can be computed independently in the field theory.

scholarly journals Time evolution of effective central charge and signatures of RG irreversibility after a quantum quench

2018 ◽  
Vol 4 (3) ◽  
Author(s):  
Axel Cortes Cubero
Keyword(s):  
Effective Charge ◽  
Central Charge ◽  
Large Mass ◽  
Field Theories ◽  
Conformal Field Theories ◽  
Temperature Dependent ◽  
Initial State ◽  
Conformal Field ◽  
Quantum Quench ◽  
Short Times

At thermal equilibrium, the concept of effective central charge for massive deformations of two-dimensional conformal field theories (CFT) is well understood, and can be defined by comparing the partition function of the massive model to that of a CFT. This temperature-dependent effective charge interpolates monotonically between the central charge values corresponding to the IR and UV fixed points at low and high temperatures, respectively. We propose a non-equilibrium, time-dependent generalization of the effective central charge for integrable models after a quantum quench, c_{\rm eff}(t), obtained by comparing the return amplitude to that of a CFT quench. We study this proposal for a large mass quench of a free boson, where the effective charge is seen to interpolate between c_{\rm eff}=0 at t=0t=0, and c_{\rm eff}\sim 1 at t\to\inftyt→∞, as is expected. We use our effective charge to define an “Ising to Tricritical Ising" quench protocol, where the charge evolves from c_{\rm eff}=1/2 at t=0t=0, to c_{\rm eff}=7/10 at t\to\inftyt→∞, the corresponding values of the first two unitary minimal CFT models. We then argue that the inverse “Tricritical Ising to Ising" quench is impossible with our methods. These conclusions can be generalized for quenches between any two adjacent unitary minimal CFT models. We finally study a large mass quench into the “staircase model" (sinh-Gordon with a particular complex coupling). At short times after the quench, the effective central charge increases in a discrete “staircase" structure, where the values of the charge at the steps can be computed in terms of the central charges of unitary minimal CFT models. When the initial state is a pure state, one always finds that c_{\rm eff}(t\to\infty)\geq c_{\rm eff}(t=0), though c_{\rm eff}(t), generally oscillates at finite times. We explore how this constraint may be related to RG flow irreversibility.

scholarly journals Defects and perturbation

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Enrico M. Brehm
Keyword(s):  
Entanglement Entropy ◽  
Topological Defects ◽  
Field Theories ◽  
Two Dimensional ◽  
Conformal Field Theories ◽  
Minimal Models ◽  
Conformal Field

Abstract We investigate perturbatively tractable deformations of topological defects in two-dimensional conformal field theories. We perturbatively compute the change in the g-factor, the reflectivity, and the entanglement entropy of the conformal defect at the end of these short RG flows. We also give instances of such flows in the diagonal Virasoro and Super-Virasoro Minimal Models.

scholarly journals Entanglement and complexity of purification in ( 1+1 )-dimensional free conformal field theories

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Hugo A. Camargo ◽  
Lucas Hackl ◽  
Michal P. Heller ◽  
Alexander Jahn ◽  
Tadashi Takayanagi ◽  
...  
Keyword(s):  
Field Theories ◽  
Conformal Field Theories ◽  
Conformal Field

scholarly journals NON-ABELIAN FRACTIONAL QUANTUM HALL STATES AND CHIRAL COSET CONFORMAL FIELD THEORIES

2000 ◽  
Vol 15 (30) ◽  
pp. 4857-4870 ◽  
Author(s):  
D. C. CABRA ◽  
E. FRADKIN ◽  
G. L. ROSSINI ◽  
F. A. SCHAPOSNIK
Keyword(s):  
Quantum Hall ◽  
Field Theories ◽  
Simons Theory ◽  
Conformal Field Theories ◽  
Fractional Quantum ◽  
Fractional Quantum Hall ◽  
Conformal Field ◽  
Quantum Hall States ◽  
Effective Lagrangian ◽  
Chern Simons

We propose an effective Lagrangian for the low energy theory of the Pfaffian states of the fractional quantum Hall effect in the bulk in terms of non-Abelian Chern–Simons (CS) actions. Our approach exploits the connection between the topological Chern–Simons theory and chiral conformal field theories. This construction can be used to describe a large class of non-Abelian FQH states.

scholarly journals Constructing Carrollian CFTs

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Nishant Gupta ◽  
Nemani V. Suryanarayana
Keyword(s):  
Scalar Fields ◽  
Higher Dimensions ◽  
Field Theories ◽  
Conformal Field Theories ◽  
Relativistic Limit ◽  
Conformal Field ◽  
Local Symmetries ◽  
Derivatives Of ◽  
Special Case

Abstract We construct classical theories for scalar fields in arbitrary Carroll spacetimes that are invariant under Carrollian diffeomorphisms and Weyl transformations. When the local symmetries are gauge fixed these theories become Carrollian conformal field theories. We show that generically there are at least two types of such theories: one in which only time derivatives of the fields appear and the other in which both space and time derivatives appear. A classification of such scalar field theories in three (and higher) dimensions up to two derivative order is provided. We show that only a special case of our theories arises in the ultra-relativistic limit of a covariant parent theory.

scholarly journals Bounds in 4D conformal field theories with global symmetry

2010 ◽  
Vol 44 (3) ◽  
pp. 035402 ◽  
Author(s):  
Riccardo Rattazzi ◽  
Slava Rychkov ◽  
Alessandro Vichi
Keyword(s):  
Field Theories ◽  
Global Symmetry ◽  
Conformal Field Theories ◽  
Conformal Field
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