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The quantum Fisher information (QFI) represents a fundamental concept in quantum physics. On the one hand, it quantifies the metrological potential of quantum states in quantum-parameter-estimation measurements. On the other hand, it is…

We investigate the optimization of graph topologies for quantum sensing networks designed to estimate weak magnetic fields. The sensors are modeled as spin systems governed by a transverse-field Ising Hamiltonian in thermal equilibrium at…

Quantum Physics · Physics 2026-04-08 Asghar Ullah , Özgür E. Müstecaplıoğlu , Matteo G. A. Paris

Efficient preparation of arbitrary entangled quantum states is crucial for quantum computation. This is particularly important for noisy intermediate scale quantum simulators relying on variational hybrid quantum-classical algorithms. To…

Quantum Physics · Physics 2024-11-18 Ananda Roy , Sameer Erramilli , Robert M. Konik

The quantum approximate optimisation algorithm (QAOA) is a hybrid quantum-classical algorithm used to approximately solve combinatorial optimisation problems. It involves multiple iterations of a parameterised ansatz comprising a problem…

Quantum Physics · Physics 2024-02-16 V. Vijendran , Aritra Das , Dax Enshan Koh , Syed M. Assad , Ping Koy Lam

The Quantum Fisher Information Matrix (QFIM) is a fundamental quantity in various subfields of quantum physics. It plays a crucial role in the study of parameterized quantum states, as it quantifies their sensitivity to variations in its…

Quantum Physics · Physics 2025-05-16 Rafael Gómez-Lurbe

The Quantum Approximate Optimisation Algorithm (QAOA) is a hybrid quantum-classical algorithm for solving combinatorial optimisation problems. QAOA encodes solutions into the ground state of a Hamiltonian, approximated by a $p$-level…

Quantum Physics · Physics 2025-05-16 V Vijendran , Dax Enshan Koh , Eunok Bae , Hyukjoon Kwon , Ping Koy Lam , Syed M Assad

Quantum sensors driven into the quantum chaotic regime can have dramatically enhanced sensitivity, which, however, depends intricately on the details of the underlying classical phase space. Here, we develop an accurate semiclassical…

Quantum Physics · Physics 2026-01-26 Mahdi RouhbakhshNabati , Daniel Braun , Henning Schomerus

To optimize the entanglement detection, we formulate the metrologically operational entanglement condition in quantum Fisher information by maximizing the QFI on the measurement orbit. Specifically, we consider two classes of typical local…

Quantum Physics · Physics 2024-10-28 Ao-Xiang Liu , Ma-Cheng Yang , Cong-Feng Qiao

Quantum Fisher information characterizes the phase sensitivity of qubits in the spin-boson model with a finite bandwidth spectrum. In contrast with Markovian reservoirs, the quantum Fisher information will flow from the environments to…

Quantum Physics · Physics 2015-06-18 Xiang Hao , Ninghua Tong , Shiqun Zhu

The quantum approximate optimization algorithm (QAOA) is known for its capability and universality in solving combinatorial optimization problems on near-term quantum devices. The results yielded by QAOA depend strongly on its initial…

Quantum Physics · Physics 2022-09-29 Xinwei Lee , Ningyi Xie , Yoshiyuki Saito , Dongsheng Cai , Nobuyoshi Asai

The Quantum Fisher Information (QFI) plays a crucial role in quantum information theory and in many practical applications such as quantum metrology. However, computing the QFI is generally a computationally demanding task. In this work we…

Quantum Physics · Physics 2021-06-25 M. Cerezo , Akira Sone , Jacob L. Beckey , Patrick J. Coles

We study the role of quantum entanglement (particle entanglement and mode entanglement) in optical phase estimation by employing the first and second quantization formalisms of quantum mechanics. The quantum Fisher information (QFI) is…

Quantum Physics · Physics 2016-09-23 Jaspreet Sahota , Nicolás Quesada , Daniel F. V. James

We propose a machine learning based approach to accelerate quantum approximate optimization algorithm (QAOA) implementation which is a promising quantum-classical hybrid algorithm to prove the so-called quantum supremacy. In QAOA, a…

Emerging Technologies · Computer Science 2020-04-07 Mahabubul Alam , Abdullah Ash-Saki , Swaroop Ghosh

Combinatorial optimization lies at the heart of numerous real-world applications. For a broad category of optimization problems, quantum computing is expected to exhibit quantum speed-up over classic computing. Among various quantum…

Quantum Physics · Physics 2025-09-23 Zixu Wang , Jack Mandell , Yangyang Xu , Jian Shi

Entanglement is widely regarded as an essential resource for a number of tasks and can in some cases be quantified by figures of merit related to those tasks. In quantum metrology, this is showcased by the connections between the quantum…

Quantum Physics · Physics 2026-03-24 Shaowei Du , Shuheng Liu , Matteo Fadel , Giuseppe Vitagliano , Qiongyi He

Quantum computing promises solutions to classically difficult and new-found problems through controlling the subtleties of quantum computing. The Quantum Approximate Optimisation Algorithm (QAOA) is a recently proposed quantum algorithm…

Quantum Physics · Physics 2024-12-24 Nicholas J. Pritchard

We propose an experimentally accessible scheme to determine lower bounds on the quantum Fisher information (QFI), which ascertains multipartite entanglement or usefulness for quantum metrology. The scheme is based on comparing the…

Quantum Physics · Physics 2016-03-14 Florian Fröwis , Pavel Sekatski , Wolfgang Dür

The characterization of entanglement is a central problem for the study of quantum many-body dynamics. Here, we propose the quantum Fisher information as a useful tool for the study of multipartite-entanglement dynamics in many-body…

Statistical Mechanics · Physics 2019-02-27 Karol Gietka , Jan Chwedeńczuk , Tomasz Wasak , Francesco Piazza

Given a quantum state with an unknown parameter, the Quantum Fisher Information (QFI) is a measure of the amount of information that an observable can extract about the parameter. QFI also quantifies the maximum achievable precision in…

Quantum Physics · Physics 2019-08-19 C. S. Sudheer Kumar , T. S. Mahesh

The Quantum approximate optimization algorithm (QAOA) is one of the most promising candidates for achieving quantum advantage through quantum-enhanced combinatorial optimization. In a typical QAOA setup, a set of quantum circuit parameters…

Quantum Physics · Physics 2021-06-15 Alexey Galda , Xiaoyuan Liu , Danylo Lykov , Yuri Alexeev , Ilya Safro