Subsystem distance after a local operator quench

• Published in: The journal of high energy physics 2020-02, Vol.2020 (2), p.1-33, Article 56
• Main Authors: Zhang, Jiaju, Calabrese, Pasquale
• Format: Article
• Language: English
• Subjects: Chains; Classical and Quantum Gravitation; Conformal Field Theory; Elementary Particles; Entanglement; Entropy; Field theory; High energy physics; Ising model; Lattice Integrable Models; Mathematical analysis; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; String Theory; Subsystems; Time dependence
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP02(2020)056

A bstract We investigate the time evolution of the subsystem trace distance and Schatten distances after local operator quenches in two-dimensional conformal field theory (CFT) and in one-dimensional quantum spin chains. We focus on the case of a subsystem being an interval embedded in the infinite line. The initial state is prepared by inserting a local operator in the ground state of the theory. We only consider the cases in which the inserted local operator is a primary field or a sum of several primaries. While a nonchiral primary operator can excite both left-moving and right-moving quasiparticles, a holomorphic primary operator only excites a right-moving quasiparticle and an anti-holomorphic primary operator only excites a left-moving one. The reduced density matrix (RDM) of an interval hosting a quasiparticle is orthogonal to the RDM of the interval without any quasiparticles. Moreover, the RDMs of two intervals hosting quasiparticles at different positions are also orthogonal to each other. We calculate numerically the entanglement entropy, Rényi entropy, trace distance, and Schatten distances in time-dependent states excited by different local operators in the critical Ising and XX spin chains. These results match the CFT predictions in the proper limit.