Exact solution of a non-Hermitian $\mathscr{PT}$-symmetric Heisenberg spin chain

Fuente: arXiv
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Autori principali: Kattel, Pradip, Pasnoori, Parameshwar R., Andrei, Natan
Natura: Preprint
Pubblicazione: 2023
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author Kattel, Pradip
Pasnoori, Parameshwar R.
Andrei, Natan
author_facet Kattel, Pradip
Pasnoori, Parameshwar R.
Andrei, Natan
contents We construct the exact solution of a non-Hermitian $\mathscr{PT}$-symmetric isotropic Heisenberg spin chain with integrable boundary fields. We find that the system exhibits two types of phases we refer to as $A$ and $B$ phases. In the $B$ type phase, the $\mathscr{PT}$- symmetry remains unbroken and it consists of eigenstates with only real energies, whereas the $A$ type phase contains a $\mathscr{PT}$-symmetry broken sector comprised of eigenstates with only complex energies and a sector of unbroken $\mathscr{PT}$-symmetry with eigenstates of real energies. The $\mathscr{PT}$-symmetry broken sector consists of pairs of eigenstates whose energies are complex conjugates of each other. The existence of two sectors in the $A$ type phase is associated with the exponentially localized bound states at the edges with complex energies which are described by boundary strings. We find that both $A$ and $B$ type phases can be further divided into sub-phases which exhibit different ground states. We also compute the bound state wavefunction in one magnon sector and find that as the imaginary value of the boundary parameter is increased, the exponentially localized wavefunction broadens thereby protruding more into the bulk, which indicates that exponentially localized bound states may not be stabilized for large imaginary values of the boundary parameter.
format Preprint
id arxiv_https___arxiv_org_abs_2301_06004
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Exact solution of a non-Hermitian $\mathscr{PT}$-symmetric Heisenberg spin chain
Kattel, Pradip
Pasnoori, Parameshwar R.
Andrei, Natan
Quantum Physics
Statistical Mechanics
High Energy Physics - Theory
Mathematical Physics
We construct the exact solution of a non-Hermitian $\mathscr{PT}$-symmetric isotropic Heisenberg spin chain with integrable boundary fields. We find that the system exhibits two types of phases we refer to as $A$ and $B$ phases. In the $B$ type phase, the $\mathscr{PT}$- symmetry remains unbroken and it consists of eigenstates with only real energies, whereas the $A$ type phase contains a $\mathscr{PT}$-symmetry broken sector comprised of eigenstates with only complex energies and a sector of unbroken $\mathscr{PT}$-symmetry with eigenstates of real energies. The $\mathscr{PT}$-symmetry broken sector consists of pairs of eigenstates whose energies are complex conjugates of each other. The existence of two sectors in the $A$ type phase is associated with the exponentially localized bound states at the edges with complex energies which are described by boundary strings. We find that both $A$ and $B$ type phases can be further divided into sub-phases which exhibit different ground states. We also compute the bound state wavefunction in one magnon sector and find that as the imaginary value of the boundary parameter is increased, the exponentially localized wavefunction broadens thereby protruding more into the bulk, which indicates that exponentially localized bound states may not be stabilized for large imaginary values of the boundary parameter.
title Exact solution of a non-Hermitian $\mathscr{PT}$-symmetric Heisenberg spin chain
topic Quantum Physics
Statistical Mechanics
High Energy Physics - Theory
Mathematical Physics
url https://arxiv.org/abs/2301.06004