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The energy levels of hydrogen-like atoms are obtained from the phase-space quantization, one of the pillars of the old quantum theory, by three different methods - (i) direct integration, (ii) Sommerfeld's original method, and (iii) complex…

We study a two-electron quantum dot molecule in a magnetic field by the direct diagonalization of the Hamiltonian matrix. The ground states of the molecule with the total spin S=0 and S=1 provide a possible realization for a qubit of a…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 A. Harju , S. Siljamäki , R. M. Nieminen

Efficiently characterising quantum systems, verifying operations of quantum devices and validating underpinning physical models, are central challenges for the development of quantum technologies and for our continued understanding of…

Bifurcations of classical orbits introduce divergences into semiclassical spectra which have to be smoothed with the help of uniform approximations. We develop a technique to extract individual energy levels from semiclassical spectra…

Chaotic Dynamics · Physics 2009-11-07 T. Bartsch , J. Main , G. Wunner

We study the relation between quantum entanglement and electron correlation in quantum chemistry calculations. We prove that the Hartree-Fock (HF) wave function does not violate Bell's inequality, thus is not entangled while the…

Quantum Physics · Physics 2007-06-25 Hefeng Wang , Sabre Kais

This book is an attempt to help students transform all of the concepts of quantum mechanics into concrete computer representations, which can be constructed, evaluated, analyzed, and hopefully understood at a deeper level than what is…

Quantum Physics · Physics 2020-01-22 Roman Schmied

In this paper we propose a ``quantum reduction procedure'' based on the reduction of algebras of differential operators on a manifold. We use these techniques to show, in a systematic way, how to relate the hydrogen atom to a family of…

Mathematical Physics · Physics 2007-05-23 A. D'Avanzo , G. Marmo , A. Valentino

The application of quantum algorithms to the study of many-particle quantum systems requires the ability to prepare wavefunctions that are relevant in the behavior of the system under study. Hamiltonian symmetries are an important…

Quantum Physics · Physics 2022-03-22 Alessandro Carbone , Davide Emilio Galli , Mario Motta , Barbara Jones

An efficient all-electron G$^0$W$^0$ method and a quasiparticle selfconsistent GW (QSGW) method for molecules are proposed in the molecular orbital space with the full random phase approximation. The convergence with basis set is examined.…

Mesoscale and Nanoscale Physics · Physics 2015-03-17 San-Huang Ke

We adapt the robust phase estimation algorithm to the evaluation of energy differences between two eigenstates using a quantum computer. This approach does not require controlled unitaries between auxiliary and system registers or even a…

Quantum Physics · Physics 2021-06-02 A. E. Russo , K. M. Rudinger , B. C. A. Morrison , A. D. Baczewski

Determining the vibrational structure of a molecule is central to fundamental applications in several areas, from atmospheric science to catalysis, fuel combustion modeling, biochemical imaging, and astrochemistry. However, when significant…

Quantum Physics · Physics 2021-12-22 Nicolas P. D. Sawaya , Francesco Paesani , Daniel P. Tabor

The calculation of the hindered roton-phonon energy levels of a hydrogen molecule in a confining potential with different symmetries is systematized for the case when the rotational angular momentum $J$ is a good quantum number. One goal of…

Condensed Matter · Physics 2009-11-07 T. Yildirim , A. B. Harris

The simulation of ion-atom collisions remains a formidable challenge due to the complex interplay between electronic and nuclear degrees of freedom. We present a hybrid quantum-classical computing framework for simulating time-dependent…

Quantum Physics · Physics 2026-02-03 Minchen Qiao , Yu-xi Liu

Quantum computing enables the efficient resolution of complex problems, often outperforming classical methods across various applications. In 2009, Harrow, Hassidim and Lloyd proposed an algorithm for solving linear systems of equations,…

Quantum chromodynamics (QCD) describes the structure of hadrons such as the proton at a fundamental level. The precision of calculations in QCD limits the precision of the values of many physical parameters extracted from collider data. For…

Quantum Physics · Physics 2022-03-14 Michael Kreshchuk , William M. Kirby , Gary Goldstein , Hugo Beauchemin , Peter J. Love

This chapter is a short pedagogical introduction to the use of quantum logic for the simulation of complex quantum systems, including a simulation example on actual quantum hardware.

Quantum Physics · Physics 2022-12-01 Giuliano Benenti , Giulio Casati

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

Quantum computers are promising for simulations of chemical and physical systems, but the limited capabilities of today's quantum processors permit only small, and often approximate, simulations. Here we present a method, classical…

A new web-server called The Molecule Calculator (MolCalc) is presented. The entry page is a molecular editor (JSmol) for interactive molecule building. The resulting structure can then be used to estimate molecular properties such as heats…

Chemical Physics · Physics 2013-07-15 Jan H. Jensen , Jimmy C. Kromann

An architecture for a quantum computer is presented in which spins associated with donors in silicon function as qubits. Quantum operations on the spins are performed using a combination of voltages applied to gates adjacent to the spins…

Quantum Physics · Physics 2015-06-26 B. E. Kane