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Quantum spin chains

Grant number: 15/23849-7
Support type:Research Projects - Thematic Grants
Duration: April 01, 2016 - March 31, 2021
Field of knowledge:Physical Sciences and Mathematics - Physics - Condensed Matter Physics
Principal Investigator:Francisco Castilho Alcaraz
Grantee:Francisco Castilho Alcaraz
Home Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
Co-Principal Investigators:José Abel Hoyos Neto
Assoc. researchers:José Abel Hoyos Neto
Associated grant(s):18/00403-1 - Entanglement entropy in non unitary quantum chains and the formulation of new exact integrable stochastic models, AV.EXT
16/10826-1 - Multi-user equipment approved in grant 2015/23849-7: computer cluster, AP.EMU
Associated scholarship(s):18/25441-3 - Nonequilibrium phase transition in spatial and temporal disordered systems, BP.PD
17/11484-0 - Dynamics of quantum quenched disordered spin chains, BP.PD
17/02987-8 - New developments in quantum spin chains, BP.PD


Since the introduction of the Heisenberg model to describe the dynamics of localized spins, quantum chains become useful tools for the appropriate understanding of the fluctuations in several physical systems. The quantum chains emerge in three interconnected topics of physics and mathematical physics, that we split in: a) Exactly integrable quantum chains - where they describe the simple evolution operators we can formulate for several interacting many body system; b) Critical phenomena and the thermodynamic properties of general quantum chains - where they usually describe the quantum fluctuations at the temperature T = 0 or/and thermal ones at T 8= 0, and c) Stochastic models - where they describe the time fluctuations in asymptotic equilibrium and non-equilibrium states. On this FAPESP project, in continuation with the last ones, we are going to study quantum chains along the above three topics. In topic a) we are going to search for new exactly integrable chains by using the Matrix Product ansatz introduced in a previous FAPESP project. In topic b) we are going to study the entanglement properties of quantum critical chains, through the calculation of the von Neumann and Rényi entanglement entropies among subsets of the entire quantum chain. We also will study the Shannon mutual information among theses subsets, since from results obtained along the previous FAPESP project, this quantity exhibits an universal behavior that characterizes the critical behavior of the quantum chain. We also will study the disorder effects in several quantum chains, by studying thermodynamic and information quantities. In topic c) we are going to introduce new models, as well to generalize several known models in order to understand which are the necessary basic ingredients that produce a space-time conformal invariance in a non-equilibrium asymptotic state. Within this topic we are going to study the disorder effects in unidimensional contact processes, where there exist a conexion with experimental results. (AU)

Scientific publications (6)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
PUSCHMANN, MARTIN; CREWSE, JACK; HOYOS, JOSE A.; VOJTA, THOMAS. Collective Modes at a Disordered Quantum Phase Transition. Physical Review Letters, v. 125, n. 2 JUL 10 2020. Web of Science Citations: 0.
ULIANA LIMA, CESAR A.; BRITO, FREDERICO; HOYOS, JOSE A.; TUROLLA VANZELLA, DANIEL A. Probing the Unruh effect with an accelerated extended system. NATURE COMMUNICATIONS, v. 10, JUL 10 2019. Web of Science Citations: 1.
ANDRADE, ERIC C.; HOYOS, JOSE A.; RACHEL, STEPHAN; VOJTA, MATTHIAS. Cluster-Glass Phase in Pyrochlore XY Antiferromagnets with Quenched Disorder. Physical Review Letters, v. 120, n. 9 MAR 2 2018. Web of Science Citations: 12.
MARD, H. JAVAN; HOYOS, JOSE A.; MIRANDA, E.; DOBROSAVLJEVIC, V. Strong-disorder approach for the Anderson localization transition. Physical Review B, v. 96, n. 4 JUL 27 2017. Web of Science Citations: 2.
BARGHATHI, HATEM; VOJTA, THOMAS; HOYOS, JOSE A. Contact process with temporal disorder. Physical Review E, v. 94, n. 2 AUG 9 2016. Web of Science Citations: 10.
QUITO, V. L.; HOYOS, JOSE A.; MIRANDA, E. Random SU(2)-symmetric spin-S chains. Physical Review B, v. 94, n. 6 AUG 3 2016. Web of Science Citations: 1.

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