Pith. sign in

REVIEW 15 cited by

Quantum Many-Body Scars and Hilbert Space Fragmentation: A Review of Exact Results

Not yet reviewed by Pith; the record is open.

This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.

SPECIMEN: schema-true, not a live event

T0 review · schema-true

One-sentence machine reading of the paper's core claim.

pith:XXXXXXXX · record.json · timestamp

arxiv 2109.00548 v2 pith:3XBMDZRT submitted 2021-09-01 cond-mat.str-el cond-mat.stat-mechquant-ph

Quantum Many-Body Scars and Hilbert Space Fragmentation: A Review of Exact Results

classification cond-mat.str-el cond-mat.stat-mechquant-ph
keywords qmbsexactexamplesquantumreviewsystemsdiscussergodicity
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
0 comments
read the original abstract

The discovery of Quantum Many-Body Scars (QMBS) both in Rydberg atom simulators and in the Affleck-Kennedy-Lieb-Tasaki (AKLT) spin-1 chain model, have shown that a weak violation of ergodicity can still lead to rich experimental and theoretical physics. In this review, we provide a pedagogical introduction to and an overview of the exact results on weak ergodicity breaking via QMBS in isolated quantum systems with the help of simple examples such as the fermionic Hubbard model. We also discuss various mechanisms and unifying formalisms that have been proposed to encompass the plethora of systems exhibiting QMBS. We cover examples of equally-spaced towers that lead to exact revivals for particular initial states, as well as isolated examples of QMBS. Finally, we review Hilbert Space Fragmentation, a related phenomenon where systems exhibit a richer variety of ergodic and non-ergodic behaviors, and discuss its connections to QMBS.

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Forward citations

Cited by 15 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Temperature Beyond Equilibrium in Isolated Quantum Many-Body Systems and Their Subsystems

    quant-ph 2026-07 conditional novelty 8.0

    A nonequilibrium temperature is defined as the coordinate of a canonical pseudolocal flow on leaves of fixed energy coherence in the state space of isolated quantum spin chains.

  2. All-order fluctuating hydrodynamics of the SYK lattice

    hep-th 2026-04 conditional novelty 8.0

    Derives the all-order fluctuating hydrodynamics effective action and transport coefficients for the SYK lattice from its microscopic pseudo-Goldstone boson action.

  3. Temperature Beyond Equilibrium in Isolated Quantum Many-Body Systems and Their Subsystems

    quant-ph 2026-07 conditional novelty 7.0

    Out-of-equilibrium inverse temperature is defined as the coordinate of a canonical flow that preserves the state's energy-coherence leaf, and it generically differs from the entropy derivative.

  4. Quantum scars from holographic boson stars

    hep-th 2026-05 unverdicted novelty 7.0

    Mini-boson stars in AdS spacetime are proposed as holographic realizations of quantum scars, exhibiting chaotic spectra with integrable subsectors, anomalously low entanglement, and robust Krylov complexity revivals.

  5. Typical entanglement entropy with charge conservation

    quant-ph 2026-04 unverdicted novelty 7.0

    Typical entanglement entropy with fixed global charge is given by the local thermal entropy at fixed charge density for both U(1) and SU(2) symmetries in the thermodynamic limit.

  6. Imprints of $U_A(1)$ chiral anomaly and disorder in the Dirac eigenspectrum of QCD at finite temperature

    hep-lat 2026-02 unverdicted novelty 7.0

    Lattice QCD calculations show intermediate statistics in Dirac eigenvalues near the chiral crossover that correlate with disorder via Polyakov loops, with Thouless conductance serving as a new probe for effective UA(1...

  7. Geometric fragmentation and anomalous thermalization in cubic dimer model

    hep-lat 2025-08 unverdicted novelty 7.0

    External electric fields in 3D U(1) quantum dimer models with staggered matter induce geometric fragmentation, weak fragmentation, and fractonic excitations in large winding sectors, producing anomalous thermalization.

  8. Krylov-Space Memory Cores

    hep-th 2026-07 conditional novelty 6.0

    Anomalous initial states in otherwise thermalizing models leave compact, stationary low-depth Krylov-space cores—regions with persistent fluctuations, Gibbs mismatch, and current activity—while generic states do not.

  9. Quantum scars from holographic boson stars

    hep-th 2026-05 unverdicted novelty 6.0

    Asymptotically AdS mini-boson stars exhibit scar-like states with random-matrix chaos signatures, embedded integrable branches, low entanglement, and Krylov complexity revivals, unlike thermal black holes.

  10. Hilbert Space Fragmentation and Gauge Symmetry

    hep-lat 2026-04 unverdicted novelty 6.0

    An emergent gauge symmetry valid only in a subset of sectors of the fragmented S=1 dipole-conserving spin chain enables exact quantum simulation of gauge theories using a non-gauge-invariant Hamiltonian.

  11. Energy-momentum and dark energy in $\boldsymbol{SU(\infty)}$-QGR quantum gravity

    gr-qc 2026-04 unverdicted novelty 6.0

    SU(∞)-QGR yields an Einstein-like energy-momentum constraint that includes spin-1 gravitons and treats inflation and accelerating expansion as order parameters tracking the evolution of the universe's quantum states u...

  12. Imprints of $U_A(1)$ chiral anomaly and disorder in the Dirac eigenspectrum of QCD at finite temperature

    hep-lat 2026-02 conditional novelty 6.0

    Intermediate Dirac eigenvalue statistics at high temperature are tied to axial U(1) restoration and Polyakov-loop disorder, with a first-ever Thouless conductance for the QCD Dirac spectrum.

  13. Robustness of near-thermal dynamics on digital quantum computers

    quant-ph 2024-10 unverdicted novelty 6.0

    Trotterized near-thermal dynamics are substantially more robust to gate and Trotter errors than assumed, enabled by linear gate-error scaling with entanglement and a random product state ensemble approximating thermal states.

  14. Energy-momentum and dark energy in $\boldsymbol{SU(\infty)}$-QGR quantum gravity

    gr-qc 2026-04 unverdicted novelty 5.0

    Invariance of the SU(∞)-QGR action under variation of the parameter-space metric produces an Einstein-like energy-momentum constraint, and Hilbert-space fragmentation is argued to classically appear as inflation, rehe...

  15. Homomorphism, substructure, and ideal: Elementary but rigorous aspects of renormalization group or hierarchical structure of topological orders

    hep-th 2025-06 unverdicted novelty 5.0

    An algebraic RG formalism for topological orders uses ideals in fusion rings to encode noninvertible symmetries and condensation rules between anyons.