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The dynamics of the nuclear-spin quantum computer with large number (L=1000) of qubits is considered using a perturbation approach, based on approximate diagonalization of exponentially large sparse matrices. Small parameters are introduced…

Quantum Physics · Physics 2007-05-23 G. P. Berman , D. I. Kamenev , V. I. Tsifrinovich

This work presents the formalism and implementation of excited state nuclear forces within density functional linear response theory (TDDFT) using a plane wave basis set. An implicit differentiation technique is developed for computing…

Other Condensed Matter · Physics 2009-11-11 Nikos L. Doltsinis , D. S. Kosov

A reduced-density-matrix (RDM)-based approach to {\em ab initio} cavity quantum electrodynamics (QED) is developed. The expectation value of the Pauli-Fierz Hamiltonian is expressed in terms of one- and two-body electronic and photonic…

Chemical Physics · Physics 2022-11-23 Joel D. Mallory , A. Eugene DePrince

The practical application of quantum technologies to chemical problems faces significant challenges, particularly in the treatment of realistic basis sets and the accurate inclusion of electron correlation effects. A direct approach to…

Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free energy ensembles in tight-binding, Hartree-Fock or Kohn-Sham density functional theory. The canonical…

Chemical Physics · Physics 2015-12-09 Anders M. N. Niklasson , Marc J. Cawkwell , Emanuel H. Rubensson , Elias Rudberg

Kohn-Sham Density Functional Theory (KS-DFT) provides the exact ground state energy and electron density of a molecule, contingent on the as-yet-unknown universal exchange-correlation (XC) functional. Recent research has demonstrated that…

Fracton models host unconventional topological orders in three and higher dimensions and provide promising candidates for quantum memory platforms. Understanding their robustness against quantum fluctuations is an important task but also…

Quantum Physics · Physics 2025-04-02 Marc Machaczek , Lode Pollet , Ke Liu

Multireference density functional theory (MR-DFT) has been a pivotal method for studying nuclear low-lying states and neutrinoless double-beta ($0\nu\beta\beta$) decay. However, quantifying their theoretical uncertainties has been a…

Nuclear Theory · Physics 2025-08-26 X. Zhang , C. C. Wang , C. R. Ding , J. M. Yao

Neural network quantum state (NNQS) has emerged as a promising candidate for quantum many-body problems, but its practical applications are often hindered by the high cost of sampling and local energy calculation. We develop a…

Quantum Physics · Physics 2023-11-02 Yangjun Wu , Chu Guo , Yi Fan , Pengyu Zhou , Honghui Shang

Solvation effect might have a tremendous influence on chemical reactions. However, precise quantum chemistry calculations are most often done either in vacuum neglecting the role of the solvent or using continuum solvent model ignoring its…

Chemical Physics · Physics 2020-07-14 Guillaume Jeanmairet , Maximilien Levesque , Daniel Borgis

The weak $\Lam N\to NN$ transition is studied in the valence quark model approach. The momentum transfer for this transition is so large that the short-distance two baryon dynamics must be taken into account. The two baryon system is…

High Energy Physics - Phenomenology · Physics 2007-05-23 Takashi Inoue , Sachiko Takeuchi , Makoto Oka

The equation of motion coupled cluster singles and doubles model (EOM-CCSD) is an accurate, black-box correlated electronic structure approach to investigate electronically excited states and electron attachment or detachment processes. It…

Chemical Physics · Physics 2023-09-18 Loïc Halbert , Andre Severo Pereira Gomes

We introduce a data-driven framework for approximating the convex set of $N$-representable two-electron reduced density matrices (2-RDMs). Traditional approaches characterize this set through linear matrix inequalities that define its…

Chemical Physics · Physics 2026-03-09 Luis H. Delgado-Granados , David A. Mazziotti

We develop a new technique, based on a low-energy theorem (LET) of NSVZ type derived in arXiv:1701.07833, for the nonperturbative investigation of SU(N) QCD with N${}_f$ massless quarks - or, more generally, of massless QCD-like theories -…

High Energy Physics - Theory · Physics 2022-07-01 Marco Bochicchio , Elisabetta Pallante

Quantum memories are critical for solid-state quantum computing devices and a good quantum memory requires both long storage time and fast read/write operations. A promising system is the Nitrogen-Vacancy (NV) center in diamond, where the…

Quantum Physics · Physics 2018-06-26 Mo Chen , Won Kyu Calvin Sun , Kasturi Saha , Jean-Christophe Jaskula , Paola Cappellaro

Quantum state tomography is a fundamental task in quantum information science, enabling detailed characterization of correlations, entanglement, and electronic structure in quantum systems. However, its exponential measurement and…

The variational two-electron reduced density matrix (v2RDM) method is generalized for the description of total angular momentum ($J$) and projection of total angular momentum ($M_{J}$) states in atomic systems described by non-relativistic…

Chemical Physics · Physics 2022-08-05 Run R. Li , Nicholas C. Rubin , A. Eugene DePrince

An effective simulation of quantum entanglement is presented using classical fields modulated with n pseudorandom phase sequences (PPSs) that constitute a n2^n-dimensional Hilbert space with a tensor product structure. Applications to…

Quantum Physics · Physics 2015-03-17 Jian Fu , Xingkun Wu

We introduce a methodology to estimate non-stabilizerness or "magic", a key resource for quantum complexity, with Neural Quantum States (NQS). Our framework relies on two schemes based on Monte Carlo sampling to quantify non-stabilizerness…

Quantum Physics · Physics 2026-01-28 Alessandro Sinibaldi , Antonio Francesco Mello , Mario Collura , Giuseppe Carleo

Two-body reduced density matrices (2RDMs) encode the essential two-electron physics of electronic states, but their quartic storage cost poses a major limitation in practical workflows. We investigate a simple protocol to compress both…

Chemical Physics · Physics 2026-05-15 Kemal Atalar , Hugh G. A. Burton , Andreas Grüneis , George H. Booth