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We introduce a quantum generalization of classical kinetic Ising models, described by a certain class of quantum many body master equations. Similarly to kinetic Ising models with detailed balance that are equivalent to certain Hamiltonian…

Quantum Physics · Physics 2015-05-14 R. Augusiak , F. M. Cucchietti , F. Haake , M. Lewenstein

In this work we consider the ground space connectivity problem for commuting local Hamiltonians. The ground space connectivity problem asks whether it is possible to go from one (efficiently preparable) state to another by applying a…

Computational Complexity · Computer Science 2017-07-17 David Gosset , Jenish C. Mehta , Thomas Vidick

We consider the problem of learning local quantum Hamiltonians given copies of their Gibbs state at a known inverse temperature, following Haah et al. [2108.04842] and Bakshi et al. [arXiv:2310.02243]. Our main technical contribution is a…

Quantum Physics · Physics 2024-02-09 Ales Wodecki , Jakub Marecek

We examine the problem of determining whether a multi-qubit two-local Hamiltonian can be made stoquastic by single-qubit unitary transformations. We prove that when such a Hamiltonian contains one-local terms, then this task can be NP-hard.…

Quantum Physics · Physics 2020-04-07 Joel Klassen , Milad Marvian , Stephen Piddock , Marios Ioannou , Itay Hen , Barbara Terhal

We extend classical methods of computational complexity to the realm of distributed computing, where they sometimes prove more effective than in their original context. Our focus is on decision problems in the LOCAL model, a setting in…

Distributed, Parallel, and Cluster Computing · Computer Science 2025-09-08 Fabian Reiter

The quantum analogue of a constraint satisfaction problem is a sum of local Hamiltonians - each local Hamiltonian specifies a local constraint whose violation contributes to the energy of the given quantum state. Formalizing the intuitive…

Quantum Physics · Physics 2008-11-25 Dorit Aharonov , Itai Arad , Zeph Landau , Umesh Vazirani

Without wasting time and effort on philosophical justifications and implications, we write down the conditions for the Hamiltonian of a quantum system for rendering it mathematically equivalent to a deterministic system. These are the…

Quantum Physics · Physics 2020-06-09 Gerard t Hooft

We show that the Hamiltonian dynamics of the self-interacting, abelian p-form theory in D=2p+2 dimensional space-time gives rise to the quasi-local structure. Roughly speaking, it means that the field energy is localized but on closed…

High Energy Physics - Theory · Physics 2007-05-23 D. Chruscinski

Finite-dimensional Quantum Mechanics can be geometrically formulated as a proper classical-like Hamiltonian theory in a projective Hilbert space. The description of composite quantum systems within the geometric Hamiltonian framework is…

Mathematical Physics · Physics 2015-12-23 Davide Pastorello

A promising approach to achieve computational supremacy over the classical von Neumann architecture explores classical and quantum hardware as Ising machines. The minimisation of the Ising Hamiltonian is known to be NP-hard problem for…

Quantum Physics · Physics 2020-08-04 Kirill P. Kalinin , Natalia G. Berloff

We consider the computational complexity of Hamiltonians which are sums of commuting terms acting on plaquettes in a square lattice of qubits, and we show that deciding whether the ground state minimizes the energy of each local term…

Quantum Physics · Physics 2011-09-29 Norbert Schuch

Local Hamiltonians, $H_k$, describe non-trivial $k$-body interactions in quantum many-body systems. Here, we address the dynamical simulatability of a $k$-local Hamiltonian by a simpler one, $H_{k'}$, with $k'<k$, under the realistic…

Quantum Physics · Physics 2024-06-06 Ayaka Usui , Anna Sanpera , María García Díaz

In these notes we address the canonical quantization of the cosmological models which appear as solutions of the low energy effective action of closed bosonic string theory (dilaton models). The analysis is restricted to the quantization of…

Mathematical Physics · Physics 2007-05-23 Gabriel Catren , Claudio Simeone

A Hamiltonian is said to be quasi-exactly solvable (QES) if some of the energy levels and the corresponding eigenfunctions can be calculated exactly and in closed form. An entirely new class of QES Hamiltonians having sextic polynomial…

Quantum Physics · Physics 2009-11-11 Carl M. Bender , Maria Monou

Motivated by understanding the power of quantum computation with restricted number of qubits, we give two complete characterizations of unitary quantum space bounded computation. First we show that approximating an element of the inverse of…

Quantum Physics · Physics 2016-11-22 Bill Fefferman , Cedric Yen-Yu Lin

Finding the ground state energy of electrons subject to an external electric field is a fundamental problem in computational chemistry. We prove that this electronic-structure problem, when restricted to a fixed single-particle basis and…

Quantum Physics · Physics 2021-03-16 Bryan O'Gorman , Sandy Irani , James Whitfield , Bill Fefferman

The entanglement Hamiltonian (EH) provides the most comprehensive characterization of bipartite entanglement in many-body quantum systems. Ground states of local Hamiltonians inherit this locality, resulting in EHs that are dominated by…

Quantum Physics · Physics 2025-04-07 Federico Rottoli , Colin Rylands , Pasquale Calabrese

We investigate bicomplex Hamiltonian systems in the framework of an analogous version of the Schrodinger equation. Since in such a setting three different types of conjugates of bicomplex numbers appear, each is found to define in a natural…

Mathematical Physics · Physics 2015-11-23 Bijan Bagchi , Abhijit Banerjee

We investigate the problem of determining the Hamiltonian of a locally interacting open-quantum system. To do so, we construct model estimators based on inverting a set of stationary, or dynamical, Heisenberg-Langevin equations of motion…

Quantum Physics · Physics 2020-08-19 Eugene F. Dumitrescu , Pavel Lougovski

The problem of finding superintegrable Hamiltonians and their integrals of motion can be reduced to solving a series of compatibility equations that result from the overdetermination of the commutator or Poisson bracket relations. The…

Mathematical Physics · Physics 2025-12-23 Ian Marquette , Anthony Parr