Nuclear Theory·nucl-th

Friday·December 29, 2017

13 papers—10 primary·3 cross-listed

11
Dynamics of entanglement in expanding quantum fields
Jürgen Berges🇩🇪 · Stefan Floerchinger🇩🇪 · Raju Venugopalan🇺🇸
We develop a novel real-time approach to computing the entanglement between spatial regions for Gaussian states in quantum field theory. The entanglement entropy is characterized in terms of local correlation functions on space-like Cauchy hypersurfaces. The framework is applied to explore an expanding light cone geometry in the particular case of the Schwinger model for quantum electrodynamics in 1+1 space-time dimensions. We observe that the entanglement entropy becomes extensive in rapidity at early times and that the corresponding local reduced density matrix is a thermal density matrix for excitations around a coherent field with a time dependent temperature. Since the Schwinger model successfully describes many features of multiparticle production in $e^{+} e^{-}$ collisions, our results provide an attractive explanation in this framework for the apparent thermal nature of multiparticle production even in the absence of significant final state scattering.
↳ hep-thhep-phnucl-thJHEP(2018)·107 citations
12
Semigroup approach to the sign problem in quantum Monte Carlo simulations
Zhong-Chao Wei🇩🇪
We propose a framework based on the concept of the semigroup to understand the fermion sign problem. By using properties of contraction semigroups, we obtain sufficient conditions for quantum lattice fermion models to be sign-problem-free. Many previous results can be considered as special cases of our new results. As a direct application of our new results, we construct a class of sign-problem-free fermion lattice models, which cannot be understood by previous frameworks. This framework also provides an interesting aspect in understanding related quantum many-body systems. We establish a series of inequalities for all the sign-problem-free fermion lattice models that satisfy our sufficient conditions.
↳ cond-mat.str-elhep-latmath-phmath.MP+1PRB(2024)·19 citations
13
High-energy $μ^{+} μ^{-}$ electroproduction
P. A. Krachkov🇷🇺 · A. I. Milstein🇷🇺
The cross sections of high-energy $μ^{+} μ^{-}$ pair production and paradimuonium production by a relativistic electron in the atomic field are discussed. The calculation is performed exactly in the parameters of the atomic field. Though the Coulomb corrections to the cross sections, related to the multiple Coulomb exchange of $μ^{+}, μ^{-}$ and an atom, are negligible, the Coulomb corrections to the differential cross sections, related to the electron interaction with an atom, are large. However, the latter Coulomb corrections to the cross sections integrated over the final electron momentum are small. Apparently, this effect can easily be observed experimentally. Furthermore, it is shown that the asymmetry of the cross section with respect to the permutation of the momenta of $μ^{-}$ and $μ^{+}$ is large.
↳ hep-phnucl-thphysics.atom-phNPA(2018)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE

Dynamics of entanglement in expanding quantum fields

Semigroup approach to the sign problem in quantum Monte Carlo simulations

High-energy μ+μ− electroproduction

Affiliations

High-energy $μ^{+} μ^{-}$ electroproduction