Hamiltonian complexity

TJ Osborne - Reports on progress in physics, 2012 - iopscience.iop.org
In recent years we have seen the birth of a new field known as Hamiltonian complexity lying
at the crossroads between computer science and theoretical physics. Hamiltonian …

Exhaustive characterization of quantum many-body scars using commutant algebras

S Moudgalya, OI Motrunich - arXiv preprint arXiv:2209.03377, 2022 - arxiv.org
We study Quantum Many-Body Scars (QMBS) in the language of commutant algebras,
which are defined as symmetry algebras of families of local Hamiltonians. This framework …

Criticality without frustration for quantum spin-1 chains

S Bravyi, L Caha, R Movassagh, D Nagaj, PW Shor - Physical review letters, 2012 - APS
Frustration-free (FF) spin chains have a property that their ground state minimizes all
individual terms in the chain Hamiltonian. We ask how entangled the ground state of a FF …

Numerical methods for detecting symmetries and commutant algebras

S Moudgalya, OI Motrunich - Physical Review B, 2023 - APS
For families of Hamiltonians defined by parts that are local, the most general definition of a
symmetry algebra is the commutant algebra, ie, the algebra of operators that commute with …

Undecidability of the spectral gap in one dimension

J Bausch, TS Cubitt, A Lucia, D Perez-Garcia - Physical Review X, 2020 - APS
The spectral gap problem—determining whether the energy spectrum of a system has an
energy gap above ground state, or if there is a continuous range of low-energy excitations …

Universality of Schmidt decomposition and particle identity

S Sciara, R Lo Franco, G Compagno - Scientific reports, 2017 - nature.com
Schmidt decomposition is a widely employed tool of quantum theory which plays a key role
for distinguishable particles in scenarios such as entanglement characterization, theory of …

Novel quantum phase transition from bounded to extensive entanglement

Z Zhang, A Ahmadain, I Klich - Proceedings of the National …, 2017 - National Acad Sciences
The nature of entanglement in many-body systems is a focus of intense research with the
observation that entanglement holds interesting information about quantum correlations in …

[HTML][HTML] Spectral gaps of frustration-free spin systems with boundary

M Lemm, E Mozgunov - Journal of Mathematical Physics, 2019 - pubs.aip.org
In quantum many-body systems, the existence of a spectral gap above the ground state has
far-reaching consequences. In this paper, we discuss “finite-size” criteria for having a …

Quantum 3-SAT Is QMA-Complete

D Gosset, D Nagaj - SIAM Journal on Computing, 2016 - SIAM
Quantum satisfiability is a constraint satisfaction problem that generalizes classical boolean
satisfiability. In the quantum k-SAT problem, each constraint is specified by a k-local …

Symmetries as Ground States of Local Superoperators: Hydrodynamic Implications

S Moudgalya, OI Motrunich - PRX Quantum, 2024 - APS
Symmetry algebras of quantum many-body systems with locality can be understood using
commutant algebras, which are defined as algebras of operators that commute with a given …