Quantum Fragmentation

Fuente: arXiv
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Auteurs principaux: Han, Yiqiu, Hart, Oliver, Khudorozhkov, Alexey, Nandkishore, Rahul
Format: Preprint
Publié: 2026
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author Han, Yiqiu
Hart, Oliver
Khudorozhkov, Alexey
Nandkishore, Rahul
author_facet Han, Yiqiu
Hart, Oliver
Khudorozhkov, Alexey
Nandkishore, Rahul
contents We introduce a systematic protocol for constructing quantum Hilbert-space-fragmented Hamiltonians, whose Krylov-sector structure, unlike in classically fragmented models, can be fully resolved only in an entangled basis. The protocol takes as input a classically fragmented model and uses a Rokhsar-Kivelson type construction to promote it to a quantum fragmented model. Notably, the procedure also works with non-fragmented inputs (such as Ising models). We explain how the Krylov sectors of the resulting quantum fragmented model may be labeled and counted in one dimension, and outline experimentally accessible verification of quantum fragmentation, assuming the ability to prepare specific initial states and perform tomography on reduced density matrices. We further analyze the entanglement structure of the entangled basis underlying quantum fragmentation, which sharply distinguishes it from both classical fragmentation and the trivial "fragmentation" of generic Hamiltonians in their eigenbasis. We also extend the construction to higher dimensions, with an explicit proof of principle example in two dimensions. We expect these results to open a new route to the systematic exploration of quantum fragmentation.
format Preprint
id arxiv_https___arxiv_org_abs_2604_06461
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quantum Fragmentation
Han, Yiqiu
Hart, Oliver
Khudorozhkov, Alexey
Nandkishore, Rahul
Quantum Physics
Statistical Mechanics
We introduce a systematic protocol for constructing quantum Hilbert-space-fragmented Hamiltonians, whose Krylov-sector structure, unlike in classically fragmented models, can be fully resolved only in an entangled basis. The protocol takes as input a classically fragmented model and uses a Rokhsar-Kivelson type construction to promote it to a quantum fragmented model. Notably, the procedure also works with non-fragmented inputs (such as Ising models). We explain how the Krylov sectors of the resulting quantum fragmented model may be labeled and counted in one dimension, and outline experimentally accessible verification of quantum fragmentation, assuming the ability to prepare specific initial states and perform tomography on reduced density matrices. We further analyze the entanglement structure of the entangled basis underlying quantum fragmentation, which sharply distinguishes it from both classical fragmentation and the trivial "fragmentation" of generic Hamiltonians in their eigenbasis. We also extend the construction to higher dimensions, with an explicit proof of principle example in two dimensions. We expect these results to open a new route to the systematic exploration of quantum fragmentation.
title Quantum Fragmentation
topic Quantum Physics
Statistical Mechanics
url https://arxiv.org/abs/2604.06461