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In the study of alternative or extended theories of gravity, Dirac's Hamiltonian constraint algorithm is invaluable for enumerating the propagating modes and gauge symmetries. For gravity, this canonical approach is frequently applied as a…

Computational Physics · Physics 2026-01-01 Will Barker

Complex molecules and mesoscopic structures are naturally described by general networks of elementary building blocks and tight-binding is one of the simplest quantum model suitable for studying the physical properties arising from the…

Condensed Matter · Physics 2009-11-07 P. Buonsante , R. Burioni , D. Cassi

Hamiltonian simulation, i.e., simulating the real time evolution of a target quantum system, is a natural application of quantum computing. Trotter-Suzuki splitting methods can generate corresponding quantum circuits; however, a faithful…

Quantum Physics · Physics 2024-03-21 Ayse Kotil , Rahul Banerjee , Qunsheng Huang , Christian B. Mendl

Adiabatic quantum computing is a universal model for quantum computing whose implementation using a gate-based quantum computer requires depths that are unreachable in the early fault-tolerant era. To mitigate the limitations of near-term…

Quantum Physics · Physics 2024-10-18 Ioannis Kolotouros , Ioannis Petrongonas , Miloš Prokop , Petros Wallden

Density matrix downfolding (DMD) is a technique for regressing low-energy effective Hamiltonians from quantum many-body Hamiltonians. One limiting factor in the accuracy of classical implementations of DMD is the presence of…

Solving partial differential equations for extremely large-scale systems within a feasible computation time serves in accelerating engineering developments. Quantum computing algorithms, particularly the Hamiltonian simulations, present a…

Quantum Physics · Physics 2024-09-10 Yuki Sato , Ruho Kondo , Ikko Hamamura , Tamiya Onodera , Naoki Yamamoto

Reconstructing the Hamiltonian of a quantum system is an essential task for characterizing and certifying quantum processors and simulators. Existing techniques either rely on projective measurements of the system before and after coherent…

Building on recent results for adiabatic gauge potentials, we propose a variational approach for computing the generator of Schrieffer-Wolff transformations. These transformations consist of block diagonalizing a Hamiltonian through a…

Strongly Correlated Electrons · Physics 2020-01-15 Jonathan Wurtz , Pieter Claeys , Anatoli Polkovnikov

We present a quantum algorithm for the dynamical simulation of time-dependent Hamiltonians. Our method involves expanding the interaction-picture Hamiltonian as a sum of generalized permutations, which leads to an integral-free Dyson series…

Quantum Physics · Physics 2021-09-15 Yi-Hsiang Chen , Amir Kalev , Itay Hen

We prove that estimating the ground state energy of a translationally-invariant, nearest-neighbour Hamiltonian on a 1D spin chain is QMAEXP-complete, even for systems of low local dimension (roughly 40). This is an improvement over the best…

Quantum Physics · Physics 2017-11-15 Johannes Bausch , Toby Cubitt , Maris Ozols

We introduce a novel method for the renormalization of the Hamiltonian operator in Quantum Field Theory in the spirit of the Wilson renormalization group. By a series of unitary transformations that successively decouples the high-frequency…

High Energy Physics - Theory · Physics 2009-10-31 G. Alexanian , E. F. Moreno

We present a novel, computationally efficient approach to accelerate quantum optimal control calculations of large multi-qubit systems used in a variety of quantum computing applications. By leveraging the intrinsic symmetry of finite…

Quantum Physics · Physics 2023-10-05 Xian Wang , Mahmut Sait Okyay , Anshuman Kumar , Bryan M. Wong

qcombo is a Python package for the symbolic evaluation of commutators between general quantum many-body operators expressed in normal-ordered form using the generalized Wick theorem. The package provides an automated and systematic…

Nuclear Theory · Physics 2026-03-26 L. H. Chen , Y. Li , H. Hergert , J. M. Yao

We present a major update to QuSpin, SciPostPhys.2.1.003 -- an open-source Python package for exact diagonalization and quantum dynamics of arbitrary boson, fermion and spin many-body systems, supporting the use of various (user-defined)…

Computational Physics · Physics 2019-08-14 Phillip Weinberg , Marin Bukov

We present a quantum algorithm for finding the minimum of a function based on multistep quantum computation and apply it for optimization problems with continuous variables, in which the variables of the problem are discretized to form the…

Quantum Physics · Physics 2023-07-03 Hefeng Wang , Hua Xiang

Based on the canonical Lang-Firsov transformation of the Hamiltonian we develop a very efficient quantum Monte Carlo algorithm for the Holstein model with one electron. Separation of the fermionic degrees of freedom by a reweighting of the…

Strongly Correlated Electrons · Physics 2007-05-23 Martin Hohenadler , Hans Gerd Evertz , Wolfgang von der Linden

The manipulation of the quantum states of light in linear optical systems has multiple applications in quantum optics and quantum computation. The package QOptCraft gives a collection of methods to solve some of the most usual problems when…

Reliable processing of quantum information for developing quantum technologies requires precise control of out-of-equilibrium many-bodysystems. This is a highly challenging task as the fragility of quantum states to external perturbations…

A class of non-Dirac-hermitian many-particle quantum systems admitting entirely real spectra and unitary time-evolution is presented. These quantum models are isospectral with Dirac-hermitian systems and are exactly solvable. The general…

Quantum Physics · Physics 2011-09-28 Pijush K. Ghosh

We propose an efficient algorithm to construct $\boldsymbol{k}\cdot \boldsymbol{p}$ effective Hamiltonians, which is much faster than the previously proposed algorithms. This algorithm is implemented in MagneticKP package. The package…

Materials Science · Physics 2023-06-28 Zeying Zhang , Zhi-Ming Yu , Gui-Bin Liu , Zhenye Li , Shengyuan A. Yang , Yugui Yao