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We present efficient circuits that can be used for the phase space tomography of quantum states. The circuits evaluate individual values or selected averages of the Wigner, Kirkwood and Husimi distributions. These quantum gate arrays can be…

Quantum Physics · Physics 2009-11-10 Juan Pablo Paz , Augusto J. Roncaglia , Marcos Saraceno

One of the major challenges for erroneous quantum computers is undoubtedly the control over the effect of noise. Considering the rapid growth of available quantum resources that are not fully fault-tolerant, it is crucial to develop…

Quantum state tomography faces exponential scaling with system size, while recent neural network approaches achieve polynomial scaling at the cost of losing the geometric structure of quantum state space. We introduce geometric latent space…

Quantum Physics · Physics 2025-12-19 S. M. Yousuf Iqbal Tomal , Abdullah Al Shafin

We propose HAMSI (Hessian Approximated Multiple Subsets Iteration), which is a provably convergent, second order incremental algorithm for solving large-scale partially separable optimization problems. The algorithm is based on a local…

Fine-grained spectral properties of quantum Hamiltonians, including both eigenvalues and their multiplicities, provide useful information for characterizing many-body quantum systems as well as for understanding phenomena such as…

Quantum Physics · Physics 2026-05-01 Zhiyan Ding , Lin Lin , Yilun Yang , Ruizhe Zhang

Quantum-selected configuration interaction (QSCI) utilizes an input quantum state on a quantum device to select important bases (electron configurations in quantum chemistry) that define a subspace in which to diagonalize a target…

Quantum Physics · Physics 2025-10-22 Mathias Mikkelsen , Yuya O. Nakagawa

The capacity for solving eigenstates with a quantum computer is key for ultimately simulating physical systems. Here we propose inverse iteration quantum eigensolvers, which exploit the power of quantum computing for the classical inverse…

Quantum Physics · Physics 2022-03-09 Min-Quan He , Dan-Bo Zhang , Z. D. Wang

We propose a stochastic variance-reduced cubic regularized Newton algorithm to optimize the finite-sum problem over a Riemannian submanifold of the Euclidean space. The proposed algorithm requires a full gradient and Hessian update at the…

Optimization and Control · Mathematics 2022-12-14 Dewei Zhang , Sam Davanloo Tajbakhsh

Predicting ground state energies of quantum many-body systems is one of the central computational challenges in quantum chemistry, physics, and materials science. Krylov subspace methods, such as Krylov Quantum Diagonalization and…

Quantum Physics · Physics 2025-12-23 Changwon Lee , Daniel K. Park

Estimating observable expectation values in eigenstates of quantum systems has a broad range of applications and is an area where early fault-tolerant quantum computers may provide practical quantum advantage. We develop a hybrid…

Quantum Physics · Physics 2026-03-03 Bence Bakó , Tenzan Araki , Bálint Koczor

We present a quantum-classical hybrid algorithm for calculating the ground state and its energy of the quantum many-body Hamiltonian by proposing an adaptive construction of a quantum state for the quantum-selected configuration interaction…

Quantum Physics · Physics 2024-12-12 Yuya O. Nakagawa , Masahiko Kamoshita , Wataru Mizukami , Shotaro Sudo , Yu-ya Ohnishi

We propose and test several tensor network based algorithms for reconstructing the ground state of an (unknown) local Hamiltonian starting from a random sample of the wavefunction amplitudes. These algorithms, which are based on completing…

Quantum Physics · Physics 2023-10-04 Aaron Stahl , Glen Evenbly

Quantum state tomography (QST) allows for the reconstruction of quantum states through measurements and some inference technique under the assumption of repeated state preparations. Bayesian inference provides a promising platform to…

Quantum Physics · Physics 2025-05-22 Hanson H. Nguyen , Kody J. H. Law , Joseph M. Lukens

Quantum error-correcting codes (QECCs) and decoherence-free subspace (DFS) codes provide active and passive means, respectively, to address certain types of errors that arise during quantum computation. The latter technique is suitable to…

Quantum Physics · Physics 2024-07-02 Nihar Ranjan Dash , Sanjoy Dutta , R. Srikanth , Subhashish Banerjee

Sampling all ground states of a Hamiltonian with equal probability is a desired feature of a sampling algorithm, but recent studies indicate that common variants of transverse field quantum annealing sample the ground state subspace…

Quantum Physics · Physics 2020-09-09 Vaibhaw Kumar , Casey Tomlin , Curt Nehrkorn , Daniel O'Malley , Joseph Dulny

Hyperspectral image super-resolution (HSI-SR) has emerged as a challenging yet critical problem in remote sensing. Existing approaches primarily focus on regularization techniques that leverage low-rankness and local smoothness priors.…

Numerical Analysis · Mathematics 2026-05-13 Jun Zhang , Chao Yi , Mingxi Ma , Mengling He , Chao Wang

Designing quantum circuits for ground state preparation is a fundamental task in quantum information science. However, standard Variational Quantum Algorithms (VQAs) are often constrained by limited ansatz expressivity and difficult…

Quantum Physics · Physics 2026-02-25 Zhijian Lai , Hantao Nie , Jiayuan Wu , Dong An

Quantum pseudorandomness, also known as unitary designs, comprise a powerful resource for quantum computation and quantum engineering. While it is known in theory that pseudorandom unitary operators can be constructed efficiently, realizing…

Quantum Physics · Physics 2019-07-24 Jun Li , Zhihuang Luo , Tao Xin , Hengyan Wang , David Kribs , Dawei Lu , Bei Zeng , Raymond Laflamme

Obtaining accurate representations of the eigenstates of an array of coupled superconducting qubits is a crucial step in the design of circuit quantum electrodynamics (QED)-based quantum processors. However, exact diagonalization of the…

The performance of quantum algorithms for ground-state energy estimation is directly impacted by the quality of the initial state, where quality is traditionally defined in terms of the overlap of the input state with the target state. An…