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Encoding the electronic structure of molecules using 2-electron reduced density matrices (2RDMs) as opposed to many-body wave functions has been a decades-long quest as the 2RDM contains sufficient information to compute the exact molecular…

Chemical Physics · Physics 2022-08-11 David Pekker , Chungwen Liang , Sankha Pattanayak , Swagatam Mukhopadhyay

A summary is presented of the properties of the coefficient matrices formed by expanding the two-body reduced density matrix in a complete set of two-electron wave functions. Calculating the relationship between the many electron wave…

Quantum Physics · Physics 2022-03-02 Nicholas Cox

We explore the principles of many-body Hamiltonian complexity reduction via downfolding on an effective low-dimensional representation. We present a unique measure of fidelity between the effective (reduced-rank) description and the full…

Computational Physics · Physics 2024-11-26 Annabelle Canestraight , Zhen Huang , Vojtech Vlcek

We present here a formulation of the electronic ground-state energy in terms of the second order reduced density matrix, using a duality argument. It is shown that the computation of the ground-state energy reduces to the search of the…

Quantum Physics · Physics 2009-11-13 Eric Cances , Gabriel Stoltz , Mathieu Lewin

Real quantum systems couple to their environment and lose their intrinsic quantum nature through the process known as decoherence. Here we present a method for minimizing decoherence by making it energetically unfavorable. We present a…

Quantum Physics · Physics 2009-11-06 D. Bacon , K. R. Brown , K. B. Whaley

It is virtually impossible to directly solve the Schr\"odinger equation for a many-electron wave function due to the exponential growth in degrees of freedom with increasing particle number. The two-body reduced density matrix (2-RDM)…

Quantum Physics · Physics 2022-04-22 Nicholas Cox

The Pauli exclusion principle is fundamental to understanding electronic quantum systems. It namely constrains the expected occupancies $n_i$ of orbitals $\varphi_i$ according to $0 \leq n_i \leq 2$. In this work, we first refine the…

In the case of compact quantum graphs, many-particle models with singular two-particle interactions where introduced in [arXiv:1207.5648, arXiv:1112.4751] to provide a paradigm for further studies on many-particle quantum chaos. In this…

Mathematical Physics · Physics 2018-01-04 Joachim Kerner , Tobias Mühlenbruch

We introduce a two-body quantum Hamiltonian model with spins-$\half$ located on the vertices of a 2D spatial lattice. The model exhibits an exact topological degeneracy in all coupling regimes. This is a remarkable non-perturbative effect.…

Quantum Physics · Physics 2010-01-07 H. Bombin , M. Kargarian , M. A. Martin-Delgado

The pair-specific ground state energy of Newtonian N-body systems grows monotonically in N. This furnishes a whole family of simple new tests for minimality of putative ground state energies obtained through computer experiments. Inspection…

Mathematical Physics · Physics 2015-05-13 Michael K. -H. Kiessling

Excited-state properties of highly correlated systems are key to understanding photosynthesis, luminescence, and the development of novel optical materials, but accurately capturing their interactions is computationally costly. We present…

Quantum Physics · Physics 2024-08-21 Irma Avdic , David A. Mazziotti

One-way quantum computing achieves the full power of quantum computation by performing single particle measurements on some many-body entangled state, known as the resource state. As single particle measurements are relatively easy to…

Quantum Physics · Physics 2013-05-29 Jianxin Chen , Xie Chen , Runyao Duan , Zhengfeng Ji , Bei Zeng

We introduce an unsupervised machine-learning framework that discovers optimally compressed representations of quantum many-body ground states. Using an autoencoder neural network architecture on data from $L$-site Fermi-Hubbard models, we…

Quantum Physics · Physics 2025-12-15 Felix Frohnert , Emiel Koridon , Stefano Polla

Human experts cannot efficiently access the physical information of quantum many-body states by simply "reading" the coefficients, but have to reply on the previous knowledge such as order parameters and quantum measurements. In this work,…

Quantum Physics · Physics 2021-10-26 Xinran Ma , Z. C. Tu , Shi-Ju Ran

In quantum many-body problems, one of the main difficulties comes from the description of non-negligible interactions which require, at least in principle, an exponential amount of information. Recently, in the context of spin glasses and…

Computational Physics · Physics 2019-02-25 Jean Michel Sellier

The exponential computational cost of describing strongly correlated electrons can be mitigated by adopting a reduced density-matrix (RDM)-based description of the electronic structure. While variational two-electron RDM (v2RDM) methods can…

Chemical Physics · Physics 2026-01-06 Grier M. Jones , Run. R. Li , A. Eugene DePrince , Konstantinos D. Vogiatzis

The variational determination of the two-fermion reduced density matrix is described for harmonically trapped, ultracold few-fermion systems in one dimension with equal spin populations. This is accomplished by formulating the problem as a…

Quantum Gases · Physics 2022-11-11 Mitchell J. Knight , Harry M. Quiney , Andy M. Martin

The problem of sampling outputs of quantum circuits has been proposed as a candidate for demonstrating a quantum computational advantage (sometimes referred to as quantum "supremacy"). In this work, we investigate whether quantum advantage…

Quantum Physics · Physics 2021-06-09 Leonardo Novo , Juani Bermejo-Vega , Raúl García-Patrón

We present a simple quantum many-body system - a two-dimensional lattice of qubits with a Hamiltonian composed of nearest-neighbor two-body interactions - such that the ground state is a universal resource for quantum computation using…

Quantum Physics · Physics 2007-05-23 Stephen D. Bartlett , Terry Rudolph

We study the low-energy spectral properties of positive center-of-mass conserving two-body Hamiltonians as they arise in models of fractional quantum Hall states. Starting from the observation that positive many-body Hamiltonians must have…

Strongly Correlated Electrons · Physics 2016-05-02 Amila Weerasinghe , Tahereh Mazaheri , Alexander Seidel