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In this article we study the effects of higher body excitations in the relativistic CC calculations for atoms and ions with one valence electron using Fock-space CCSD, CCSD(T) and its unitary variants. The present study demonstrates that…

Atomic Physics · Physics 2009-11-13 Chiranjib Sur , Rajat K Chaudhuri

A robust system for use of Quantum Computation using neutral atoms is presented in this communication. This scheme exploits a multilevel atomic system interacting with two lasers in such a way that it leads to formation of two Coherent…

Quantum Physics · Physics 2012-09-03 Ashok Vudayagiri

Quantum simulation offers a route to study open-system molecular dynamics in non-perturbative regimes by programming the interactions among electronic, vibrational, and environmental degrees of freedom on similar energy scales. Trapped-ion…

We present a novel approach for efficient preparation of electronic ground states, leveraging the optimizer ExcitationSolve [J\"ager et al., Comm. Phys. (2025)] and established variational quantum eigensolver-based operator selection…

Quantum Physics · Physics 2026-02-13 Max Haas , Thierry N. Kaldenbach , Thomas Hammerschmidt , Daniel Barragan-Yani

We consider $N_a$ three-level atoms (or systems) interacting with a one-mode electromagnetic field in the dipolar and rotating wave approximations. The order of the quantum phase transitions is determined explicitly for each of the…

Quantum Physics · Physics 2013-12-02 S. Cordero , O. Castaños , R. López-Peña , E. Nahmad-Achar

Entanglement of spin and orbital degrees of freedom drives the formation of novel quantum and topological physical states. Discovering new spin-orbit entangled ground states and emergent phases of matter requires both experimentally probing…

Strongly Correlated Electrons · Physics 2017-05-18 A. E. Taylor , S. Calder , R. Morrow , H. L. Feng , M. H. Upton , M. D. Lumsden , K. Yamaura , P. M. Woodward , A. D. Christianson

We extend our assessment of the potential of perturbative coupled cluster (CC) expansions for a test set of open-shell atoms and organic radicals to the description of quadruple excitations. Namely, the second- through sixth-order models of…

Chemical Physics · Physics 2016-05-17 Janus J. Eriksen , Devin A. Matthews , Poul Jørgensen , Jürgen Gauss

Quantum embedding methods have recently developed significantly to model large molecular structures. This work proposes a novel wave function theory in density functional theory (WTF-in-DFT) embedding scheme based on pair-coupled cluster…

Chemical Physics · Physics 2024-01-10 Rahul Chakraborty , Katharina Boguslawski , Paweł Tecmer

We present the first implementation and applications of non-Dyson algebraic diagrammatic construction theory for charged excitations in three-dimensional periodic solids (EA/IP-ADC). The EA/IP-ADC approach has a computational cost similar…

Materials Science · Physics 2022-11-15 Samragni Banerjee , Alexander Yu. Sokolov

It is known that any bipartite unitary operator of Schmidt rank three is equivalent to a controlled unitary under local unitaries. We propose a standard form of such operators. Using the form we improve the upper bound for the entanglement…

Quantum Physics · Physics 2016-04-22 Lin Chen , Li Yu

The three key elements of a quantum simulation are state preparation, time evolution, and measurement. While the complexity scaling of time evolution and measurements are well known, many state preparation methods are strongly…

Quantum Physics · Physics 2022-03-24 Trevor Keen , Bo Peng , Karol Kowalski , Pavel Lougovski , Steven Johnston

Estimating molecular ground-state energies is a central application of quantum computing, requiring both the preparation of accurate quantum states and efficient energy readout. Understanding the effect of hardware noise on these…

Quantum Physics · Physics 2025-12-23 Ludwig Nützel , Michael J. Hartmann , Henrik Dreyer , Etienne Granet

The integration of diverse quantum resources and the exploitation of more degrees of freedom provide key operational flexibility for universal fault-tolerant quantum computation. In this work, we propose a flexible…

Quantum Physics · Physics 2026-03-20 Peilin Du , Jing Zhang , Tiancai Zhang , Rongguo Yang , Kui Liu , Jiangrui Gao

In this work, we present a systematic study of the occupied and unoccupied electronic states of LaCoO$_{3}$ compound using DFT, DFT+$\textit{U}$ and DFT+embedded DMFT methods. The value of $\textit{U}$ used here is evaluated by using…

Strongly Correlated Electrons · Physics 2018-08-10 Paromita Dutta , Sohan Lal , Sudhir K. Pandey

Quantum state preparation is a fundamental primitive in quantum algorithms for encoding classical data into quantum amplitudes. We compare the cost of preparing general $n$-qubit states with real amplitudes using two common paradigms:…

Quantum Physics · Physics 2026-05-20 Diyi Liu , Hanyu Wang , Shuchen Zhu , Jason Cong , Wibe A. de Jong , Di Fang , Zhen Huang , Costin Iancu , Chao Yang

The cost of a partitioned fluid-structure interaction scheme is typically assessed by the number of coupling iterations required per time step, while ignoring the Newton loops within the nonlinear sub-solvers. In this work, we discuss why…

Numerical Analysis · Mathematics 2021-07-01 Thomas Spenke , Norbert Hosters , Marek Behr

Improving the description of the equation of state (EoS) of deuterium-tritium (DT) has recently been shown to change significantly the gain of an Inertial Confinement Fusion (ICF) target (Hu et al., PRL 104, 235003 (2010)). We use here an…

Plasma Physics · Physics 2015-05-28 Laurent Caillabet , Benoit Canaud , Gwenaël Salin , Stéphane Mazevet , Paul Loubeyre

A method and codes for two-step correlation calculation of heavy-atom molecules have been developed, employing the generalized relativistic effective core potential and relativistic coupled cluster (RCC) methods at the first step, followed…

Chemical Physics · Physics 2009-11-07 A. N. Petrov , N. S. Mosyagin , T. A. Isaev , A. V. Titov , V. F. Ezhov , E. Eliav , U. Kaldor

We compute the energy per particle of infinite symmetric nuclear matter from chiral N3LO (next-to-next-to-next-to-leading order) two-body potentials plus N2LO three-body forces. The low-energy constants of the chiral three-nucleon force…

Nuclear Theory · Physics 2014-04-28 L. Coraggio , J. W. Holt , N. Itaco , R. Machleidt , L. E. Marcucci , F. Sammarruca

Molecular ground-state simulation is one of the most promising fields for demonstrating practical quantum advantage on near-term quantum computers. However, the Variational Quantum Eigensolver (VQE), a leading algorithm for this task, still…

Quantum Physics · Physics 2025-07-08 Runhong He , Qiaozhen Chai , Xin Hong , Ji Guan , Guolong Cui , Shengbin Wang , Shenggang Ying