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We propose an efficient and almost optimal scheme for measuring molecular Hamiltonians in quantum chemistry on quantum computers, which requires $2N^2$ distinct measurements in the leading order with $N$ being the number of molecular…

Quantum Physics · Physics 2024-04-02 Wataru Inoue , Koki Aoyama , Yusuke Teranishi , Keita Kanno , Yuya O. Nakagawa , Kosuke Mitarai

We introduce a quantum information theory-inspired method to improve the characterization of many-body Hamiltonians on near-term quantum devices. We design a new class of similarity transformations that, when applied as a preprocessing…

Quantum Physics · Physics 2024-07-24 Andi Gu , Hong-Ye Hu , Di Luo , Taylor L. Patti , Nicholas C. Rubin , Susanne F. Yelin

This work uncovers a fundamental connection between doped stabilizer states, a concept from quantum information theory, and the structure of eigenstates in perturbed many-body quantum systems. We prove that for Hamiltonians consisting of a…

Quantum Physics · Physics 2025-01-09 Andi Gu , Salvatore F. E. Oliviero , Lorenzo Leone

We develop a computational method to learn a molecular Hamiltonian matrix from matrix-valued time series of the electron density. As we demonstrate for three small molecules, the resulting Hamiltonians can be used for electron density…

Computational Physics · Physics 2020-09-01 Harish S. Bhat , Karnamohit Ranka , Christine M. Isborn

Correlated many-body problems ubiquitously appear in various fields of physics such as condensed matter physics, nuclear physics, and statistical physics. However, due to the interplay of the large number of degrees of freedom, it is…

Strongly Correlated Electrons · Physics 2018-02-12 Hiroyuki Fujita , Yuya O. Nakagawa , Sho Sugiura , Masaki Oshikawa

We consider 1D lattices described by Hubbard or Bose-Hubbard models, in the presence of periodic high-frequency perturbations, such as uniform ac force or modulation of hopping coefficients. Effective Hamiltonians for interacting particles…

Other Condensed Matter · Physics 2015-08-18 A. P. Itin , M. I. Katsnelson

In the last years, we have been witnessing a tremendous push to demonstrate that quantum computers can solve classically intractable problems. This effort, initially focused on the hardware, progressively included the simplification of the…

Quantum Physics · Physics 2024-01-26 Lane G. Gunderman , Andrew J. Jena , Luca Dellantonio

In this article, we propose general criteria to construct optimal atomic centered basis sets in quantum chemistry. We focus in particular on two criteria, one based on the ground-state one-body density matrix of the system and the other…

Numerical Analysis · Mathematics 2023-11-14 Eric Cancès , Geneviève Dusson , Gaspard Kemlin , Laurent Vidal

Projection of Bloch states obtained from quantum-mechanical calculations onto atomic orbitals is the fastest scheme to construct ab-initio tight-binding Hamiltonian matrices. However, the presence of spurious states and unphysical…

Quantum computer provides new opportunities for quantum chemistry. In this article, we present a versatile, extensible, and efficient software package, named Q$^2$Chemistry, for developing quantum algorithms and quantum inspired classical…

Quantum Physics · Physics 2023-01-18 Yi Fan , Jie Liu , Xiongzhi Zeng , Zhiqian Xu , Honghui Shang , Zhenyu Li , Jinlong Yang

Precision control of a quantum system requires accurate determination of the effective system Hamiltonian. We develop a method for estimating the Hamiltonian parameters for some unknown two-state system and providing uncertainty bounds on…

Quantum simulations of electronic structure with a transformed Hamiltonian that includes some electron correlation effects are demonstrated. The transcorrelated Hamiltonian used in this work is efficiently constructed classically, at…

We present a systematic hierarchy of approximations for {\it local} exact-decoupling of four-component quantum chemical Hamiltonians based on the Dirac equation. Our ansatz reaches beyond the trivial local approximation that is based on a…

Chemical Physics · Physics 2012-06-28 Daoling Peng , Markus Reiher

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

Preparing the ground state of a given Hamiltonian and estimating its ground energy are important but computationally hard tasks. However, given some additional information, these problems can be solved efficiently on a quantum computer. We…

Quantum Physics · Physics 2020-12-16 Lin Lin , Yu Tong

The preparation of highly entangled many-body systems is one of the central challenges of both basic and applied science. The complexity of interparticle interaction and environment coupling increases rapidly with the number of…

Quantum Physics · Physics 2013-09-20 Felix Platzer , Florian Mintert , Andreas Buchleitner

We consider quantum systems with a Hamiltonian containing a weak perturbation i.e. $\boldsymbol{H=H_0} + \boldsymbol{\lambda} \cdot \boldsymbol{\tilde{H}}$, $\boldsymbol{\lambda}= \{\lambda_1, \lambda_2,...\}$, $\boldsymbol{\tilde{H}}$ $=…

Quantum Physics · Physics 2025-02-18 Sidali Mohammdi , Matteo Bina , Abdelhakim Gharbi , Matteo G. A. Paris

Significant progress in the development of efficient and fast algorithms for quantum chemical calculations has been made in the past two decades. The main focus has always been the desire to be able to treat ever larger molecules or…

Chemical Physics · Physics 2012-12-18 Moritz P. Haag , Markus Reiher

Describing matter at near absolute zero temperature requires understanding a system's quantum ground state and the low energy excitations around it, the quasiparticles, which are thermally populated by the system's contact to a heat bath.…

Strongly Correlated Electrons · Physics 2009-11-10 Claudio Chamon

First-quantized, real-space formulations of quantum chemistry on quantum computers are appealing: qubit count scales logarithmically with spatial resolution, and Coulomb operators achieve quadratic instead of quartic computational scaling…