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Reflections are omnipresent tools in quantum algorithms. We consider the task of reflecting through the eigenspace of an implementable unitary. Such reflections are generally designed using phase estimation or linear combination of…

Quantum Physics · Physics 2025-04-16 Baptiste Claudon

Simulation of quantum chemistry is expected to be a principal application of quantum computing. In quantum simulation, a complicated Hamiltonian describing the dynamics of a quantum system is decomposed into its constituent terms, where the…

Quantum Physics · Physics 2020-03-04 Yingkai Ouyang , David R. White , Earl T. Campbell

We develop a quantum filter diagonalization method (QFD) that lies somewhere between the variational quantum eigensolver (VQE) and the phase estimation algorithm (PEA) in terms of required quantum circuit resources and conceptual…

Quantum Physics · Physics 2019-09-20 Robert M. Parrish , Peter L. McMahon

As a cornerstone of automated reasoning, equational reasoning finds equivalences between symbolic expressions and fuels advances across scientific disciplines. Yet, its potential remains limited by the exponential growth of equivalent…

Quantum Physics · Physics 2026-05-19 Davide Rattacaso , Daniel Jaschke , Marco Ballarin , Ilaria Siloi , Simone Montangero

It is well known that the unitary evolution of a closed $M-$level quantum system can be generated by a non-Hermitian Hamiltonian $H$ with real spectrum. Its Hermiticity can be restored via an amended inner-product metric $\Theta$. In…

Quantum Physics · Physics 2023-07-31 Miloslav Znojil

We present a systematic study of quantum system compression for the evolution of generic many-body problems. The necessary numerical simulations of such systems are seriously hindered by the exponential growth of the Hilbert space dimension…

Quantum Physics · Physics 2021-01-20 Robert L. Kosut , Tak-San Ho , Herschel Rabitz

Determining ground state energies of quantum systems by hybrid classical/quantum methods has emerged as a promising candidate application for near-term quantum computational resources. Short of large-scale fault-tolerant quantum computers,…

Quantum Physics · Physics 2016-10-25 Nicholas C. Rubin

Non-Hermitian physics has emerged as a rich field of study, with applications ranging from $PT$-symmetry breaking and skin effects to non-Hermitian topological phase transitions. Yet most studies remain restricted to small-scale or…

Quantum Physics · Physics 2025-10-06 Xiao-Ming Zhang , Yukun Zhang , Wenhao He , Xiao Yuan

The procedure for simulating the nuclear magnetic resonance spectrum linked to the spin system of a molecule for a certain nucleus entails diagonalizing the associated Hamiltonian matrix. As the dimensions of said matrix grow exponentially…

Quantum Physics · Physics 2024-10-29 Joaquín Ossorio-Castillo , Alexandre Rodríguez-Coello

With the applications of quantum computing becoming more and more widespread, finding ways that allow end users without experience in the field to apply quantum computers to solve their individual problems is becoming a crucial task.…

Quantum Physics · Physics 2024-04-18 Damian Rovara , Nils Quetschlich , Robert Wille

Reducing the complexity of quantum algorithms to treat quantum chemistry problems is essential to demonstrate an eventual quantum advantage of Noisy-Intermediate Scale Quantum (NISQ) devices over their classical counterpart. Significant…

Quantum Physics · Physics 2022-12-07 Emiel Koridon , Saad Yalouz , Bruno Senjean , Francesco Buda , Thomas E. O'Brien , Lucas Visscher

A many-body Hamiltonian can be block-diagonalized by expressing it in terms of symmetry-adapted basis states. Finding the group orbit representatives of these basis states and their corresponding symmetries is currently a…

Quantum Physics · Physics 2019-04-17 Albert T. Schmitz , Sonika Johri

We demonstrate that it is possible to construct operators that stabilize the constraint-satisfying subspaces of computational problems in their Ising representations. We provide an explicit recipe to construct unitaries and associated…

Solvability of the rational quantum integrable systems related to exceptional root spaces $G_2, F_4$ is re-examined and for $E_{6,7,8}$ is established in the framework of a unified approach. It is shown the Hamiltonians take algebraic form…

High Energy Physics - Theory · Physics 2009-11-10 Konstantin G. Boreskov , Alexander V. Turbiner , Juan C. Lopez Vieyra

Many eigenvalue problems arising in practice are often of the generalized form $A\x=\lambda B\x$. One particularly important case is symmetric, namely $A, B$ are Hermitian and $B$ is positive definite. The standard algorithm for solving…

Quantum Physics · Physics 2021-10-20 Changpeng Shao , Jin-Peng Liu

We present the Quantum Hamiltonian Analysis Toolkit (QHAT), a newly developed application that provides a user-friendly interface for studying Hamiltonians and performing Hamiltonian simulation on fault-tolerant quantum computers. QHAT…

A general strategy is provided to identify the most general metric for diagonalizable pseudo-Hermitian and anti-pseudo-Hermitian Hamilton operators represented by two-dimensional matrices. It is investigated how a permutation of the…

Quantum Physics · Physics 2021-02-17 Frieder Kleefeld

Encryption schemes often derive their power from the properties of the underlying algebra on the symbols used. Inspired by group theoretic tools, we use the centralizer of a subgroup of operations to present a private-key quantum…

Quantum Physics · Physics 2020-02-21 Si-Hui Tan , Joshua A. Kettlewell , Yingkai Ouyang , Lin Chen , Joseph F. Fitzsimons

The random matrix ensembles are applied to the quantum statistical two-dimensional systems of electrons. The quantum systems are studied using the finite dimensional real, complex and quaternion Hilbert spaces of the eigenfunctions. The…

Statistical Mechanics · Physics 2007-05-23 Maciej M. Duras

Executing quantum algorithms over distributed quantum systems requires quantum circuits to be divided into sub-circuits which communicate via entanglement-based teleportation. Naively mapping circuits to qubits over multiple quantum…

Quantum Physics · Physics 2026-02-05 Felix Burt , Kuan-Cheng Chen , Kin K. Leung