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We propose an efficient circuit structure of variational quantum circuit \textit{Ans\"{a}tze} used for the variational quantum eigensolver (VQE) algorithm in calculating gapped topological phases on the currently feasible noisy…

Quantum Physics · Physics 2023-08-21 Rong-Yang Sun , Tomonori Shirakawa , Seiji Yunoki

Efficiently calculating the low-lying eigenvalues of Hamiltonians, written as sums of Pauli operators, is a fundamental challenge in quantum computing. While various methods have been proposed to reduce the complexity of quantum circuits…

Quantum Physics · Physics 2025-08-08 Abhinav Anand , Kenneth R. Brown

Characterizing quantum critical states towards the thermodynamic limit is essential for understanding phases of matter. The power of quantum simulators for preparing the critical states relies crucially on the structure of quantum circuits…

Quantum Physics · Physics 2026-03-31 Mei Peng , Xu-Dan Xie , Dan-Bo Zhang

Variational quantum eigensolvers (VQEs) are a promising class of quantum algorithms for preparing approximate ground states in near-term quantum devices. Minimizing the error in such an approximation requires designing ansatzes using…

Quantum Physics · Physics 2021-12-06 Y. Herasymenko , T. E. O'Brien

Variational quantum eigensolver (VQE), which attracts attention as a promising application of noisy intermediate-scale quantum devices, finds a ground state of a given Hamiltonian by variationally optimizing the parameters of quantum…

Quantum Physics · Physics 2022-05-12 Fumiyoshi Kobayashi , Kosuke Mitarai , Keisuke Fujii

Combinatorial optimization problems have wide-ranging applications in industry and academia. Quantum computers may help solve them by sampling from carefully prepared Ansatz quantum circuits. However, current quantum computers are limited…

Quantum Physics · Physics 2025-11-07 Sabina Drăgoi , Alberto Baiardi , Daniel J. Egger

Quantum simulations are bound to be one of the main applications of near-term quantum computers. Quantum chemistry and condensed matter physics are expected to benefit from these technological developments. Several quantum simulation…

Quantum Physics · Physics 2018-01-04 Pierre-Luc Dallaire-Demers , Jonathan Romero , Libor Veis , Sukin Sim , Alán Aspuru-Guzik

The Variational Quantum Eigensolver (VQE) is a quantum algorithm used to find the ground state energy of a given Hamiltonian. The key component of VQE is the ansatz, which is a trial wavefunction that the algorithm uses to approximate the…

Quantum Physics · Physics 2023-10-05 Yilin Shen

We explore how to build quantum circuits that compute the lowest energy state corresponding to a given Hamiltonian within a Symmetry subspace by explicitly encoding it into the circuit. We create an explicit unitary and a variationally…

Quantum Physics · Physics 2021-12-28 Raja Selvarajan , Manas Sajjan , Sabre Kais

We propose an implementation of a two-dimensional $\mathbb{Z}_2$ lattice gauge theory model on a shallow quantum circuit, involving a number of single and two-qubits gates comparable to what can be achieved with present-day and near-future…

Hybrid quantum-classical algorithms have been proposed to circumvent noise limitations in quantum computers. Such algorithms delegate only a calculation of the expectation value to the quantum computer. Among them, the Variational Quantum…

Strongly Correlated Electrons · Physics 2022-11-02 Baptiste Anselme Martin , Pascal Simon , Marko J. Rančić

Quantum algorithms for electronic-structure simulations are actively being developed, yet many hybrid quantum-classical approaches are bottlenecked by the measurement overhead associated with large molecular Hamiltonians. Here we introduce…

Quantum Physics · Physics 2026-03-10 Benjamin Mokhtar , Noboru Inoue , Takashi Tsuchimochi

We propose a novel variational method for solving the sub-graph isomorphism problem on a gate-based quantum computer. The method relies (1) on a new representation of the adjacency matrices of the underlying graphs, which requires a number…

Quantum Physics · Physics 2022-09-05 Nicola Mariella , Andrea Simonetto

Many computational problems are unchanged under some symmetry operation. In classical machine learning, this can be reflected with the layer structure of the neural network. In quantum machine learning, the ansatz can be tuned to correspond…

We introduce a hybrid quantum-classical variational algorithm to simulate ground-state phase diagrams of frustrated quantum spin models in the thermodynamic limit. The method is based on a cluster-Gutzwiller ansatz where the wave function…

Quantum Physics · Physics 2022-12-14 Daniel Huerga

We introduce a variational quantum annealing (VarQA) algorithm for electronic structure theory, in which we use the quantum annealer as a sampler and prepare an ansatz state through its statistics. We also introduce a strategy called the…

Quantum Physics · Physics 2025-03-20 Ka-Wa Yip , Kübra Yeter-Aydeniz , Sijia S. Dong

Obtaining exact solutions to combinatorial optimization problems using classical computing is computationally expensive. The current tenet in the field is that quantum computers can address these problems more efficiently. While promising…

Quantum Physics · Physics 2025-12-23 Xiaoyang Wang , Yahui Chai , Xu Feng , Yibin Guo , Karl Jansen , Cenk Tüysüz

The variational quantum eigensolver algorithm has gained attentions due to its capability of locating the ground state and ground energy of a Hamiltonian, which is a fundamental task in many physical and chemical problems. Although it has…

Quantum Physics · Physics 2024-10-07 Trung Huynh , Gwangil An , Minsu Kim , Yu-Seong Jeon , Jinhyoung Lee

Harnessing the full power of nascent quantum processors requires the efficient management of a limited number of quantum bits with finite lifetime. Hybrid algorithms leveraging classical resources have demonstrated promising initial results…

Quantum algorithms offer a compelling new avenue for addressing difficult NP-complete optimization problems, such as the Generalized Assignment Problem (GAP). Given the operational constraints of contemporary Noisy Intermediate-Scale…

Quantum Physics · Physics 2025-11-05 Carlo Mastroianni , Francesco Plastina , Jacopo Settino , Andrea Vinci