Entanglement-spectrum characterization of ground-state nonanalyticities in coupled excitation-phonon models

Vladimir M. Stojanović
Phys. Rev. B 101, 134301 – Published 2 April 2020

Abstract

The polaron concept captures physical situations involving an itinerant quantum particle (excitation) that interacts strongly with bosonic degrees of freedom and becomes heavily boson-dressed. While the Gerlach-Löwen theorem rules out the occurrence of nonanalyticities of ground-state-related quantities for a broad class of polaron models, examples were found in recent years of sharp transitions pertaining to strongly momentum-dependent interactions of an excitation with dispersionless (zero-dimensional) phonons. On the example of a lattice model with Peierls-type excitation-phonon interaction, such level-crossing-type small-polaron transitions are analyzed here through the prism of the entanglement spectrum of the excitation-phonon system. By evaluating this spectrum in a numerically exact fashion it is demonstrated that the behavior of the entanglement entropy in the vicinity of the critical excitation-phonon coupling strength chiefly originates from one specific entanglement-spectrum eigenvalue, namely the smallest one. While the discrete translational symmetry of the system implies that those eigenvalues can be labeled by the bare-excitation quasimomentum quantum numbers, here it is shown numerically that they are predominantly associated with the quasimomenta 0 and π, including cases where a transition between the two takes place deeply in the strong-coupling regime.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Received 3 January 2020
  • Revised 10 February 2020
  • Accepted 16 March 2020

DOI:https://doi.org/10.1103/PhysRevB.101.134301

©2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied PhysicsQuantum Information, Science & Technology

Authors & Affiliations

Vladimir M. Stojanović*

  • Institut für Angewandte Physik, Technical University of Darmstadt, D-64289 Darmstadt, Germany

  • *vladimir.stojanovic@physik.tu-darmstadt.de

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 101, Iss. 13 — 1 April 2020

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×