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We introduce real-time density matrix embedding theory (DMET), a dynamical quantum embedding theory for computing non-equilibrium electron dynamics in strongly correlated systems. As in the previously developed static DMET, real-time DMET…

Chemical Physics · Physics 2017-11-03 Joshua S. Kretchmer , Garnet Kin-Lic Chan

Efficient simulation of interacting fermionic systems is a key application of near-term quantum computers, but is hindered by the overhead required to encode fermionic operators on qubit hardware. Here, we consider models with $N$ fermionic…

Quantum Physics · Physics 2026-04-30 Reinis Irmejs , J. Ignacio Cirac

Modeling composite systems of spins or electrons coupled to bosonic modes is of significant interest for many fields of applied quantum physics and chemistry. A quantum simulation can allow for the solution of quantum problems beyond…

A previously developed quantum reduced-order model is revised and applied, together with the domain decomposition, to develop the quantum element method (QEM), a methodology for fast and accurate simulation of quantum eigenvalue problems.…

Computational Physics · Physics 2023-04-18 Ming-C. Cheng

The reduced density matrix (RDM) is crucial in quantum many-body systems for understanding physical properties, including all local physical quantity information. This study aims to minimize various error constraints that causes challenges…

Quantum Physics · Physics 2024-01-01 Nayuta Takemori , Yusuke Teranishi , Wataru Mizukami , Nobuyuki Yoshioka

We present and analyze the fermionic time evolving density matrix using orthogonal polynomials algorithm (fTEDOPA), which enables the numerically exact simulation of open quantum systems coupled to a fermionic environment. The method allows…

Quantum Physics · Physics 2020-05-08 Alexander Nüßeler , Ish Dhand , Susana F. Huelga , Martin B. Plenio

Quantum embedding methods enable the study of large, strongly correlated quantum systems by (usually self-consistent) decomposition into computationally manageable subproblems, in the spirit of divide-and-conquer methods. Among these,…

Strongly Correlated Electrons · Physics 2025-03-14 Alicia Negre , Fabian Faulstich , Raehyun Kim , Thomas Ayral , Lin Lin , Eric Cancès

Quantum simulations of metal surfaces are critical for catalytic innovation. Yet existing methods face a cost-accuracy dilemma: density functional theory is efficient but system-dependent in accuracy, while wavefunction-based theories are…

Chemical Physics · Physics 2026-04-10 Changsu Cao , Hung Q. Pham , Zhen Guo , Yutan Zhang , Zigeng Huang , Xuelan Wen , Ji Chen , Dingshun Lv

A broad spectrum of physical systems in condensed-matter and high-energy physics, vibrational spectroscopy, and circuit and cavity QED necessitates the incorporation of bosonic degrees of freedom, such as phonons, photons, and gluons, into…

Quantum Physics · Physics 2025-02-28 Bo Peng , Yuan Su , Daniel Claudino , Karol Kowalski , Guang Hao Low , Martin Roetteler

Computing the exact dynamics of many-body quantum systems becomes intractable as system size grows. Here, we present a symmetry-based method that provides an exponential reduction in the complexity of a broad class of such problems…

Dynamical mean-field theory (DMFT) is a useful tool to analyze models of strongly correlated fermions like the Hubbard model. In DMFT, the lattice of the model is replaced by a single impurity site embedded in an effective bath. The…

Quantum Physics · Physics 2026-03-27 Stefan Wolf , Martin Eckstein , Michael J. Hartmann

Simulating fermionic systems on a quantum computer requires representing fermionic states using qubits. The complexity of many simulation algorithms depends on the complexity of implementing rotations generated by fermionic…

Quantum Physics · Physics 2024-10-08 Joseph Carolan , Luke Schaeffer

Quantum error mitigation (QEM) is a class of promising techniques capable of reducing the computational error of variational quantum algorithms tailored for current noisy intermediate-scale quantum computers. The recently proposed…

Quantum Physics · Physics 2022-05-17 Yifeng Xiong , Soon Xin Ng , Lajos Hanzo

Cross-platform verification, a critical undertaking in the realm of early-stage quantum computing, endeavors to characterize the similarity of two imperfect quantum devices executing identical algorithms, utilizing minimal measurements.…

Quantum Physics · Physics 2023-11-08 Yang Qian , Yuxuan Du , Zhenliang He , Min-hsiu Hsieh , Dacheng Tao

Motivated by recent cold-atom realisations of matter-wave waveguide QED, we study simple fermionic impurity models and discuss fermionic analogues of several paradigmatic phenomena in quantum optics, including formation of non-trivial bound…

Quantum Physics · Physics 2024-07-23 Bennet Windt , Miguel Bello , Eugene Demler , J. Ignacio Cirac

Despite being a pillar of quantum mechanics, little attention has been paid to the onset of Fermi's golden rule as a discrete microscopic bath of modes approaches the macroscopic thermodynamic limit and forms a continuum. Motivated by…

Quantum Physics · Physics 2025-05-22 Amir Burshtein , Moshe Goldstein

Quantum simulation represents the most promising quantum application to demonstrate quantum advantage on near-term noisy intermediate-scale quantum (NISQ) computers, yet available quantum simulation algorithms are prone to errors and thus…

Quantum Physics · Physics 2024-10-01 Shin Sun , Li-Chai Shih , Yuan-Chung Cheng

Impurity Hamiltonians are systems of $N$ fermionic modes where $O(1)$ of them interact among themselves via quartic (or higher order) fermion terms, while coupling quadratically with $O(N)$ bath modes. Without the quartic interactions,…

Quantum Physics · Physics 2026-04-10 N. C. Mai Pham , Raul A. Santos

We simulate the excited states of the Lipkin model using the recently proposed Quantum Equation of Motion (qEOM) method. The qEOM generalizes the EOM on classical computers and gives access to collective excitations based on quasi-boson…