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In the realm of quantum information processing, the efficient characterization of entangled states poses an overwhelming challenge, rendering the traditional methods including quantum tomography unfeasible and impractical. To tackle this…

Quantum Physics · Physics 2025-12-09 Ye-Chao Liu , Jiangwei Shang

Variational quantum eigensolver (VQE), which combines quantum systems with classical computational power, has been arisen as a promising candidate for near-term quantum computing applications. However, the experimental resources such as the…

For parameter estimation from an $N$-component composite quantum system, it is known that a separable preparation leads to a mean-squared estimation error scaling as $1/N$ while an entangled preparation can in some conditions afford a…

Quantum Physics · Physics 2019-04-04 Francois Chapeau-Blondeau

Detecting and quantifying quantum entanglement remain significant challenges in the noisy intermediate-scale quantum (NISQ) era. This study presents the implementation of quantum support vector machines (QSVMs) on IBM quantum devices to…

Quantum Physics · Physics 2025-04-10 M. Mahdian , Z. Mousavi

Measurements are essential for the processing and protection of information in quantum computers. They can also induce long-range entanglement between unmeasured qubits. However, when post-measurement states depend on many non-deterministic…

The concept of randomized measurements on individual particles has proven to be useful for analyzing quantum systems and is central for methods like shadow tomography of quantum states. We introduce $\textit{collective}$ randomized…

Quantum Physics · Physics 2024-08-12 Satoya Imai , Géza Tóth , Otfried Gühne

We show how entanglement can be used to improve the estimation of an unknown transformation. Using entanglement is always of benefit, in improving either the precision or the stability of the measurement. Examples relevant for applications…

Quantum Physics · Physics 2019-05-15 G. Mauro D'Ariano , Paoloplacido Lo Presti , Matteo G. A. Paris

We introduce a general model for a network of quantum sensors, and we use this model to consider the question: When can entanglement between the sensors, and/or global measurements, enhance the precision with which the network can measure a…

Quantum Physics · Physics 2018-02-28 Timothy J. Proctor , Paul A. Knott , Jacob A. Dunningham

Quantum information theory and quantum computing are theoritical basis of quantum computers. Thanks to entanglement, quantum mechanical systems are provisioned to realize many information processing problems faster than classical…

Quantum Physics · Physics 2017-04-19 Volkan Erol

We propose a new measure of non-classicality of quantum gates which is particularly suitable for probabilistic devices. This measure enables to compare, e.g., deterministic devices which prepare entangled states with low amount of…

Quantum Physics · Physics 2013-07-01 Karel Lemr , Antonín Černoch , Jan Soubusta , Miloslav Dušek

Quantum metrology aims at achieving enhanced performance in measuring unknown parameters by utilizing quantum resources. Thus, quantum metrology is an important application of quantum technologies. Photonic systems can implement these…

Quantum Physics · Physics 2023-05-18 Madhura Ghosh Dastidar , Aprameyan Desikan , Vidya Praveen Bhallamudi

This thesis explores the use of entangled states in quantum computation and quantum information science. Entanglement, a quantum phenomenon with no classical counterpart, has been identified as an important and quantifiable resource in many…

Quantum Physics · Physics 2008-08-12 Hyeyoun Chung

A critical requirement for diverse applications in Quantum Information Science is the capability to disseminate quantum resources over complex quantum networks. For example, the coherent distribution of entangled quantum states together…

Quantum Physics · Physics 2009-11-11 C. W. Chou , H. de Riedmatten , D. Felinto , S. V. Polyakov , S. J. van Enk , H. J. Kimble

Quantum metrology plays a fundamental role in many scientific areas. However, the complexity of engineering entangled probes and the external noise raise technological barriers for realizing the expected precision of the to-be-estimated…

Quantum Physics · Physics 2021-01-21 Xiaodong Yang , Xi Chen , Jun Li , Xinhua Peng , Raymond Laflamme

Measurements with randomly chosen settings determine many important properties of quantum states without the need for a shared reference frame or calibration. They naturally emerge in the context of quantum communication and quantum…

Obtaining the expectation value of an observable on a quantum computer is a crucial step in the variational quantum algorithms. For complicated observables such as molecular electronic Hamiltonians, a common strategy is to present the…

Quantum Physics · Physics 2022-04-20 Tzu-Ching Yen , Aadithya Ganeshram , Artur F. Izmaylov

Before the availability of large scale fault-tolerant quantum devices, one has to find ways to make the most of current noisy intermediate-scale quantum devices. One possibility is to seek smaller repetitive hybrid quantum-classical tasks…

Quantum Physics · Physics 2023-04-12 Teiko Heinosaari , Daniel Reitzner , Alessandro Toigo

The recent emergence of novel computational devices, such as quantum computers, coherent Ising machines, and digital annealers presents new opportunities for hardware-accelerated hybrid optimization algorithms. Unfortunately, demonstrations…

Optimization and Control · Mathematics 2020-10-21 Yuchen Pang , Carleton Coffrin , Andrey Y. Lokhov , Marc Vuffray

Quantifying quantum entanglement is a pivotal challenge in quantum information science, particularly for high-dimensional systems, due to its computational complexity. This thesis extends the geometric measure of entanglement (GME) to…

Quantum Physics · Physics 2025-06-16 Xuanran Zhu

Important properties of a quantum system are not directly measurable, but they can be disclosed by how fast the system changes under controlled perturbations. In particular, asymmetry and entanglement can be verified by reconstructing the…