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In the broad context of physics ranging from classical experimental optics to quantum mechanics of unitary as well as non-unitary systems there emerge interesting phenomena related to the presence of the so called Kato's exceptional points…

Quantum Physics · Physics 2018-09-17 Miloslav Znojil

We address the problem of coupling non-Hermitian systems, treated as fundamental rather than effective theories, to the electromagnetic field. In such theories the observables are not the $\bs{x}$ and $\bs{p}$ appearing in the Hamiltonian,…

Quantum Physics · Physics 2009-11-13 H. F. Jones

Topology played an important role in physics research during the last few decades. In particular, the quantum geometric tensor that provides local information about topological properties has attracted much attention. It will reveal…

A new and intuitive perturbative approach to time-dependent quantum mechanics problems is presented, which is useful in situations where the evolution of the Hamiltonian is slow. The state of a system which starts in an instantaneous…

Quantum Physics · Physics 2009-11-11 R. MacKenzie , E. Marcotte , H. Paquette

We introduce a family of Hamiltonian systems for measurement-based quantum computation with continuous variables. The Hamiltonians (i) are quadratic, and therefore two body, (ii) are of short range, (iii) are frustration-free, and (iv)…

Quantum Physics · Physics 2011-03-01 Leandro Aolita , Augusto J. Roncaglia , Alessandro Ferraro , Antonio Acín

In this work we propose a many-body Hamiltonian construction which introduces only a single separate energy scale of order $\Theta(1/N^{2+\delta})$, for a small parameter $\delta>0$, and for $N$ terms in the target Hamiltonian. In its…

Quantum Physics · Physics 2019-12-03 Johannes Bausch

The quantum circuit model is the de-facto way of designing quantum algorithms. Yet any level of abstraction away from the underlying hardware incurs overhead. In the era of near-term, noisy, intermediate-scale quantum (NISQ) hardware with…

Quantum Physics · Physics 2021-08-27 Laura Clinton , Johannes Bausch , Toby Cubitt

In this report, we explore the use of a quantum optimization algorithm for obtaining low energy conformations of protein models. We discuss mappings between protein models and optimization variables, which are in turn mapped to a system of…

Parity-time ($PT$)-symmetric Hamiltonians exhibit non-unitary dynamical evolution while maintaining real spectra, and offer unique approaches to quantum sensing and entanglement generation. Here we present a method for simulating the…

Quantum Physics · Physics 2026-01-15 Maryam Abbasi , Koray Aydogan , Anthony W. Schlimgen , Kade Head-Marsden

Exponentiation of Hamiltonians refers to a mathematical operation to a Hamiltonian operator, typically in the form e^(-i.t.H), where H is the Hamiltonian and t is a time parameter. This operation is fundamental in quantum mechanics,…

Quantum Physics · Physics 2025-02-11 Gerard Fleury , Philippe Lacomme

We propose a general strategy to develop quantum many-body approximations of primitives in linear algebra algorithms. As a practical example, we introduce a coupled-cluster inspired framework to produce approximate Hamiltonian moments, and…

Chemical Physics · Physics 2025-12-30 Yuhang Ai , Huanchen Zhai , Johannes Tölle , Garnet Kin-Lic Chan

We model quasi-two-dimensional two-electron Quantum Dots in a parabolic confinement potential with rovibrational and purely vibrational effective Hamiltonian operators. These are optimized by non-linear least-square fits to the exact energy…

Mesoscale and Nanoscale Physics · Physics 2017-04-27 Torsten Victor Zache , Aniruddha Chakraborty

We show that the general Heisenberg Hamiltonian with non-uniform couplings can be characterised by mapping the entanglement it generates as a function of time. Identification of the Hamiltonian in this way is possible as the coefficients of…

Quantum Physics · Physics 2007-05-23 Jared H. Cole , Simon J. Devitt , Lloyd C. L. Hollenberg

Ground states of local Hamiltonians can be generally highly entangled: any quantum circuit that generates them (even approximately) must be sufficiently deep to allow coupling (entanglement) between any pair of qubits. Until now this…

Quantum Physics · Physics 2019-07-22 Lior Eldar , Aram W. Harrow

In quantum simulation, many-body phenomena are probed in controllable quantum systems. Recently, simulation of Bose-Hubbard Hamiltonians using cold atoms revealed previously hidden local correlations. However, fermionic many-body Hubbard…

Mesoscale and Nanoscale Physics · Physics 2016-04-26 J. Salfi , J. A. Mol , R. Rahman , G. Klimeck , M. Y. Simmons , L. C. L. Hollenberg , S. Rogge

We propose a perturbation algorithm for Hamiltonian systems on a Lie algebra $\mathbb{V}$, so that it can be applied to non-canonical Hamiltonian systems. Given a Hamiltonian system that preserves a subalgebra $\mathbb{B}$ of $\mathbb{V}$,…

Dynamical Systems · Mathematics 2021-01-06 Lorenzo Valvo , Michel Vittot

In this work we extend the notion of universal quantum Hamiltonians to the setting of translationally-invariant systems. We present a construction that allows a two-dimensional spin lattice with nearest-neighbour interactions, open…

Quantum Physics · Physics 2020-01-23 Stephen Piddock , Johannes Bausch

We demonstrate how a one parameter family of interacting non-commuting Hamiltonians, which are physically equivalent, can be constructed in non-commutative quantum mechanics. This construction is carried out exactly (to all orders in the…

High Energy Physics - Theory · Physics 2009-11-11 Frederik G Scholtz , Biswajit Chakraborty , Sunandan Gangopadhyay , Arindam Ghosh Hazra

Explicit symplectic integrators have been important tools for accurate and efficient approximations of mechanical systems with separable Hamiltonians. For the first time, the article proposes for arbitrary Hamiltonians similar integrators,…

Numerical Analysis · Mathematics 2016-10-19 Molei Tao

Implementing the time evolution under a desired target Hamiltonian is critical for various applications in quantum science. Due to the exponential increase in the number of parameters with system size and experimental imperfections, this…

Quantum Physics · Physics 2025-12-11 Pascal Baßler , Markus Heinrich , Martin Kliesch