Non-magnetic impurities as a quantum microscope of finite size effects in spin chains
Abstract
Finite-size effects are ubiquitous in quantum matter, yet typically invisible in the thermodynamic limit; when system size is restricted, boundaries and confinement reveal modified spectra, correlations, and emergent phenomena. With growing access to well-controlled few-spin systems, these effects are now directly observable and offer a route to probing universal physics and enabling quantum information applications. Here, we study finite-size physics in the quasi-one-dimensional Ising-like quantum antiferromagnet Ba(Co1−xMgx)2V2O8 with x = 2% and x = 5%, where non-magnetic Mg2+ ions fragment the Co2+ spin chains into finite segments. Combining inelastic neutron scattering and numerical calculations, we identify distinct regimes with fundamentally different low-energy quantum excitations: spinons confined to chain boundaries, and a cluster mode in shorter chains corresponding to a collective reversal of the Néel-ordered segment without classical analogue. Our results demonstrate how chemical substitution acts as a quantum microscope providing direct access to boundary-shaped excitations in strongly correlated spin systems.
Related
- Rapid mixing of quantum spin chains at any finite temperature
- Effect of non-homogeneous non-magnetic Impurities in Superconductors: A comparison between Microscopic and Macroscopic theories
- Finite-temperature mass gap and quench dynamics of mobile impurities in a Fermi gas
- Efficient simulations of spectra and transport for multiorbital quantum impurities
- Floquet Engineering of Quantum Transport through two Driven Impurities
BibTeX
@misc{faure2026nonmagnetic,
title = {{Non-magnetic impurities as a quantum microscope of finite size effects in spin chains}},
author = {Quentin Faure and Shintaro Takayoshi and Virginie Simonet and Béatrice Grenier and Stéphane Raymond and Eric Ressouche and Xavier Fabrèges and Pascal Lejay and Thierry Giamarchi and Sylvain Petit},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.34596},
eprint = {2610.34596},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.34596},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Non-magnetic impurities as a quantum microscope of finite size effects in spin chains
AU - Quentin Faure
AU - Shintaro Takayoshi
AU - Virginie Simonet
AU - Béatrice Grenier
AU - Stéphane Raymond
AU - Eric Ressouche
AU - Xavier Fabrèges
AU - Pascal Lejay
AU - Thierry Giamarchi
AU - Sylvain Petit
PY - 2026
DA - 2026/10/25
PB - arXiv
DO - 10.48550/arxiv.2610.34596
UR - https://arxiv.org/abs/2610.34596
AB - Finite-size effects are ubiquitous in quantum matter, yet typically invisible in the thermodynamic limit; when system size is restricted, boundaries and confinement reveal modified spectra, correlations, and emergent phenomena. With growing access to well-controlled few-spin systems, these effects are now directly observable and offer a route to probing universal physics and enabling quantum information applications. Here, we study finite-size physics in the quasi-one-dimensional Ising-like quantum antiferromagnet Ba(Co_1−xMg_x)_2V_2O_8 with x = 2% and x = 5%, where non-magnetic Mg^2+ ions fragment the Co^2+ spin chains into finite segments. Combining inelastic neutron scattering and numerical calculations, we identify distinct regimes with fundamentally different low-energy quantum excitations: spinons confined to chain boundaries, and a cluster mode in shorter chains corresponding to a collective reversal of the Néel-ordered segment without classical analogue. Our results demonstrate how chemical substitution acts as a quantum microscope providing direct access to boundary-shaped excitations in strongly correlated spin systems.
ER -