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A potential approach for demonstrating quantum advantage is using quantum computers to simulate fermionic systems. Quantum algorithms for fermionic system simulation usually involve the Hamiltonian evolution and measurements. However, in…

Quantum Physics · Physics 2025-05-14 Qing-Song Li , Jiaxuan Zhang , Huan-Yu Liu , Qingchun Wang , Yu-Chun Wu , Guo-Ping Guo

We compute the ground-state properties of fully polarized, trapped, one-dimensional fermionic systems interacting through a gaussian potential. We use an antisymmetric artificial neural network, or neural quantum state, as an ansatz for the…

Nuclear Theory · Physics 2024-02-09 J. W. T. Keeble , M. Drissi , A. Rojo-Francàs , B. Juliá-Díaz , A. Rios

Continuous-variable systems enable key quantum technologies in computation, communication, and sensing. Bosonic Gaussian states emerge naturally in various such applications, including gravitational-wave and dark-matter detection. A…

We consider process tomography for unitary quantum channels. Given access to an unknown unitary channel acting on a $\textsf{d}$-dimensional qudit, we aim to output a classical description of a unitary that is $\varepsilon$-close to the…

Quantum Physics · Physics 2024-07-31 Jeongwan Haah , Robin Kothari , Ryan O'Donnell , Ewin Tang

Despite rapid recent advances in quantum machine learning, the field is in many ways stuck. Existing approaches can exhibit serious limitations, and we still lack learning frameworks that are simple, interpretable, scalable, and naturally…

Detecting when a quantum state leaves the efficiently simulable fermionic Gaussian regime is a central task for benchmarking quantum devices and certifying fermionic magic resources. We develop practical tests and witnesses based on…

Quantum Physics · Physics 2026-05-27 Tobias Haug , Xhek Turkeshi , Piotr Sierant

We consider the entropy and decoherence in fermionic quantum systems. By making a Gaussian Ansatz for the density operator of a collection of fermions we study statistical 2-point correlators and express the entropy of a system fermion in…

High Energy Physics - Theory · Physics 2012-11-06 Tomislav Prokopec , Michael G. Schmidt , Jan Weenink

Tensor network quantum states are powerful tools for strongly correlated systems, tailored to capture local correlations such as in ground states with entanglement area laws. When applying tensor network states to interacting fermionic…

Strongly Correlated Electrons · Physics 2025-01-10 Ang-Kun Wu , Benedikt Kloss , Wladislaw Krinitsin , Matthew T. Fishman , J. H. Pixley , E. M. Stoudenmire

We introduce a new mathematical object, the "fermionant" ${\mathrm{Ferm}}_N(G)$, of type $N$ of an $n \times n$ matrix $G$. It represents certain $n$-point functions involving $N$ species of free fermions. When N=1, the fermionant reduces…

Strongly Correlated Electrons · Physics 2011-08-12 Shailesh Chandrasekharan , Uwe-Jens Wiese

Conservation of symmetries plays a crucial role in both classical and quantum simulations of many-body systems, enabling the tracking of states with specific symmetry properties and leading to substantial reductions in the number of…

Quantum Physics · Physics 2025-11-18 Ilias Magoulas , Francesco A. Evangelista

Free-fermionic states, also known as fermionic Gaussian states, represent an important class of quantum states ubiquitous in physics. They are uniquely and efficiently described by their correlation matrix. However, in practical…

Quantum Physics · Physics 2025-10-10 Lennart Bittel , Antonio Anna Mele , Jens Eisert , Lorenzo Leone

As is well-known in the context of topological insulators and superconductors, short-range-correlated fermionic pure Gaussian states with fundamental symmetries are systematically classified by the periodic table. We revisit this topic from…

Quantum Physics · Physics 2022-01-14 Zongping Gong , Tommaso Guaita

We present a new primitive for quantum algorithms that implements a discrete Hermite transform efficiently, in time that depends logarithmically in both the dimension and the inverse of the allowable error. This transform, which maps basis…

Quantum Physics · Physics 2025-10-07 Siddhartha Jain , Vishnu Iyer , Rolando D. Somma , Ning Bao , Stephen P. Jordan

We consider the problem of learning low-degree quantum objects up to $\varepsilon$-error in $\ell_2$-distance. We show the following results: $(i)$ unknown $n$-qubit degree-$d$ (in the Pauli basis) quantum channels and unitaries can be…

Near-term quantum simulators are mostly based on qubit-based architectures. However, their imperfect nature significantly limits their practical application. The situation is even worse for simulating fermionic systems, which underlie most…

Quantum Physics · Physics 2023-11-29 Qingyu Li , Chiranjib Mukhopadhyay , Abolfazl Bayat

In this work, we characterize the $t$-th order commutants of fermionic Gaussian unitaries and of their particle-preserving subgroup acting on $n$ fermionic modes. These commutants govern Haar averages over the corresponding groups and…

Quantum Physics · Physics 2026-04-02 Paolo Braccia , N. L. Diaz , Martin Larocca , M. Cerezo , Diego García-Martín

An important class of fermionic observables, relevant in tasks such as fermionic partial tomography and estimating energy levels of chemical Hamiltonians, are the binary measurements obtained from the product of anti-commuting Majorana…

Quantum Physics · Physics 2025-11-19 Daniel McNulty , Susane Calegari , Michał Oszmaniec

We study the problem of learning similarity functions over very large corpora using neural network embedding models. These models are typically trained using SGD with sampling of random observed and unobserved pairs, with a number of…

Machine Learning · Statistics 2018-07-20 Walid Krichene , Nicolas Mayoraz , Steffen Rendle , Li Zhang , Xinyang Yi , Lichan Hong , Ed Chi , John Anderson

Recent results have established dramatic advantages in learning properties of quantum states when a quantum computer is available to process or jointly measure multiple copies of the unknown quantum state. Learning tasks can be accomplished…

Quantum Physics · Physics 2026-05-08 Spencer Dimitroff , John Kallaugher , Ashe Miller , Mohan Sarovar

It is shown that discrete-time quantum walks can be used to digitize, i.e., to time discretize fermionic models of continuous-time lattice gauge theory. The resulting discrete-time dynamics is thus not only manifestly unitary, but also…

Quantum Physics · Physics 2025-02-28 Pablo Arnault , Armando Pérez , Pablo Arrighi , Terry Farrelly