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Brick Wall Quantum Circuits with Global Fermionic Symmetry

by Pietro Richelli, Kareljan Schoutens, Alberto Zorzato

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Submission summary

Authors (as registered SciPost users): Alberto Zorzato
Submission information
Preprint Link: scipost_202407_00034v2  (pdf)
Date accepted: 2024-09-16
Date submitted: 2024-09-09 12:12
Submitted by: Zorzato, Alberto
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
Specialties:
  • Condensed Matter Physics - Theory
  • Quantum Physics
Approaches: Theoretical, Computational

Abstract

We study brick wall quantum circuits enjoying a global fermionic symmetry. The constituent 2-qubit gate, and its fermionic symmetry, derive from a 2-particle scattering matrix in integrable, supersymmetric quantum field theory in 1+1 dimensions. Our 2-qubit gate, as a function of three free parameters, is of so-called free fermionic or matchgate form, allowing us to derive the spectral structure of both the brick wall unitary $U_F$ and its, non-trivial, hamiltonian limit $H_{\gamma}$ in closed form. We find that the fermionic symmetry pins $H_{\gamma}$ to a surface of critical points, whereas breaking that symmetry leads to non-trivial topological phases. We briefly explore quench dynamics for this class of circuits.

Author indications on fulfilling journal expectations

  • Provide a novel and synergetic link between different research areas.
  • Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
  • Detail a groundbreaking theoretical/experimental/computational discovery
  • Present a breakthrough on a previously-identified and long-standing research stumbling block

Author comments upon resubmission

We thank again the referees for their comments. We followed their suggestions and implemented some further changes in the manuscript which are summarized below. We hope this will further increase the readability of the manuscript.

List of changes

- clarified how the commutation relation works for the boundary matrix K
-made spin notation consistent in eq. 1.2
-corrected a typo in eq. 2.4 to clarify how parity affects local operators in graded tensor products
-enlarged fontsize for numerical plots

Published as SciPost Phys. 17, 087 (2024)

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