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The problem of identifiability of model parameters for open quantum systems is considered by investigating two-level dephasing systems. We discuss under which conditions full information about the Hamiltonian and dephasing parameters can be…

Quantum Physics · Physics 2015-01-15 Er-ling Gong , Weiwei Zhou , S. G. Schirmer , Zhi-Qiang Sun , Ming Zhang

A quantum system whose internal Hamiltonian is not strongly regular or/and control Hamiltonians are not full connected, are thought to be in the degenerate cases. In this paper, convergence problems of the multi-control Hamiltonians closed…

Systems and Control · Computer Science 2014-08-20 Shuang Cong , Fangfang Meng , Jianxiu Liu

We show that a singlet of many multi-level quantum systems arises naturally as the ground state of a physically-motivated Hamiltonian. The Hamiltonian simply exchanges the states of nearest-neighbours in some network of qudits (d-level…

Quantum Physics · Physics 2008-06-06 Christopher Hadley , Sougato Bose

Recently, there has been an increasing interest in modelling and computation of physical systems with neural networks. Hamiltonian systems are an elegant and compact formalism in classical mechanics, where the dynamics is fully determined…

Numerical Analysis · Mathematics 2022-06-28 Elena Celledoni , Andrea Leone , Davide Murari , Brynjulf Owren

The braiding operations of quantum states have attracted substantial attention due to their great potential for realizing topological quantum computations. In this paper, we show that a three-fold degenerate eigen subspace can be obtained…

Correlations between a system and its environment lead to errors in an open quantum system. Detecting those correlations would be valuable for avoiding and/or correcting those errors. Here we show that we can detect correlations by only…

Quantum Physics · Physics 2021-10-13 Sarah Hagen , Mark Byrd

The main purpose of this paper is to give a topological and symplectic classification of completely integrable Hamiltonian systems in terms of characteristic classes and other local and global invariants.

Differential Geometry · Mathematics 2007-05-23 Nguyen Tien Zung

Local Hamiltonians arise naturally in physical systems. Despite its seemingly `simple' local structure, exotic features such as nonlocal correlations and topological orders exhibit in eigenstates of these systems. Previous studies for…

Quantum Physics · Physics 2020-10-30 Shi-Yao Hou , Ningping Cao , Sirui Lu , Yi Shen , Yiu-Tung Poon , Bei Zeng

The Lagrange identity expresses the second derivative of the moment of inertia of a system of material points through kinetic energy and homogeneous potential energy, from which follows the Jacobi well-known result on the instability of a…

Exactly Solvable and Integrable Systems · Physics 2026-03-31 A. V. Tsiganov

In quantum information theory, the reliable and effective detection of entanglement is of paramount importance. However, given an unknown state, assessing its entanglement is a challenging task. To attack this problem, we investigate the…

Quantum Physics · Physics 2015-12-09 Jochen Szangolies , Hermann Kampermann , Dagmar Bruß

Hamiltonian Learning (HL) is essential for validating quantum systems in quantum computing. Not all Hamiltonians can be uniquely recovered from a steady state. HL success depends on the Hamiltonian model and steady state. Here, we analyze…

Quantum Physics · Physics 2023-09-19 Jing Zhou , D. L. Zhou

Symmetries in a Hamiltonian play an important role in quantum physics because they correspond directly with conserved quantities of the related system. In this paper, we propose quantum algorithms capable of testing whether a Hamiltonian…

Quantum Physics · Physics 2023-12-29 Margarite L. LaBorde , Mark M. Wilde

We ask whether the knowledge of a single eigenstate of a local Hamiltonian is sufficient to uniquely determine the Hamiltonian. We present evidence that the answer is "yes" for generic local Hamiltonians, given either the ground state or an…

Quantum Physics · Physics 2019-07-10 Xiao-Liang Qi , Daniel Ranard

Entanglement are the non-local correlations permitted by quantum theory, believed to play a fundamental role in a quantum computer. We have investigated these correlations in a number of theoretical models for condensed matter systems. Such…

Quantum Physics · Physics 2007-05-23 Stein Olav Skrøvseth

The relevance in Physics of non-Hermitian operators with real eigenvalues is being widely recognized not only in quantum mechanics but also in other areas, such as quantum optics, quantum fluid dynamics and quantum field theory. %stochastic…

Quantum Physics · Physics 2020-04-16 Natália Bebiano , João da Providência , S. Nishiyama , João P. da Providência

We present a method to show that low-energy states of quantum many-body interacting systems in one spatial dimension are nonlocal. We assign a Bell inequality to the Hamiltonian of the system in a natural way and we efficiently find its…

We consider the task of intrinsic control system identification for quantum devices. The problem of experimental determination of subspace confinement is considered, and simple general strategies for full Hamiltonian identification and…

Quantum Physics · Physics 2009-11-13 Sonia Schirmer , Daniel Oi , Simon Devitt

The presence of symmetries, be they discrete or continuous, in a physical system typically leads to a reduction in the problem to be solved. Here we report that neither translational invariance nor rotational invariance reduce the…

Quantum Physics · Physics 2008-07-24 Alastair Kay

In the holonomic approach to quantum computation information is encoded in a degenerate eigenspace of a parametric family of Hamiltonians and manipulated by the associated holonomic gates. These are realized in terms of the non-abelian…

Quantum Physics · Physics 2009-10-31 Jiannis Pachos , Paolo Zanardi , Mario Rasetti

Within the Hamiltonian formulation of diffeomorphism invariant theories we address the problem of how to determine and how to reduce diffeomorphisms outside the identity component.

General Relativity and Quantum Cosmology · Physics 2009-10-30 Domenico Giulini