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In this paper we shall introduce the mathematical framework for the description of measurements of quantum processes. Using this framework the process estimation problems can be treated in the similar way as the state estimation problems,…

Quantum Physics · Physics 2009-11-13 Mario Ziman

When one performs a continuous measurement, whether on a classical or quantum system, the measurement provides a certain average rate at which one becomes certain about the state of the system. For a quantum system this is an average rate…

Quantum Physics · Physics 2009-11-10 Kurt Jacobs

We establish fundamental and general techniques for formal verification of quantum protocols. Quantum protocols are novel communication schemes involving the use of quantum-mechanical phenomena for representation, storage and transmission…

Quantum Physics · Physics 2007-05-23 Simon Gay , Rajagopal Nagarajan , Nikolaos Papanikolaou

We propose and evaluate experimentally an approach to quantum process tomography that completely removes the scaling problem plaguing the standard approach. The key to this simplification is the incorporation of prior knowledge of the class…

Quantum Physics · Physics 2015-05-14 M. P. A. Branderhorst , J. Nunn , I. A. Walmsley , R. L. Kosut

We show that quantum detector tomography can be applied to the human visual system to explore human perception of photon number states. In detector tomography, instead of using very hard to produce photon number states, the response of a…

Quantum Physics · Physics 2023-01-20 T. H. A. van der Reep , D. Molenaar , W. Löffler , Y. Pinto

Quantum Parameter Estimation (QPE) is important from the perspective of both fundamental quantum research and various practical applications of quantum technologies such as for developing optimal quantum control strategies. Standard and…

Quantum Physics · Physics 2024-07-18 Bijita Sarma , Junxin Chen , Sangkha Borah

Estimation of physical observables for unknown quantum states is an important problem that underlies a wide range of fields, including quantum information processing, quantum physics, and quantum chemistry. In the context of quantum…

Quantum Physics · Physics 2024-05-21 Yuma Nakamura , Yoshichika Yano , Nobuyuki Yoshioka

We present an efficient tensor-network based algorithm for finding the optimal adaptive quantum channel discrimination strategies inspired by recently developed numerical methods in quantum metrology to find the optimal adaptive channel…

Quantum Physics · Physics 2026-02-11 Stanisław Sieniawski , Rafał Demkowicz-Dobrzański

The temporal evolution of a quantum system can be characterized by quantum process tomography, a complex task that consumes a number of physical resources scaling exponentially with the number of subsystems. An alternative approach to the…

Quantum phenomena offer the possibility of measuring physical quantities with precision beyond classical limits. However, current progress is constrained by scalability, environmental noise, and challenges in practical integration. This…

Quantum Physics · Physics 2025-10-24 George Mihailescu , Uesli Alushi , Roberto Di Candia , Simone Felicetti , Karol Gietka

Quantum metrology enhances measurement precision by utilising the properties of quantum physics. In interferometry, this is typically achieved by evolving highly-entangled quantum states before performing single-shot measurements to reveal…

Quantum Physics · Physics 2023-01-11 Kawthar Al Rasbi , Almut Beige , Lewis A. Clark

In quantum mechanics, the process of measurement is a subtle interplay between extraction of information and disturbance of the state of the quantum system. A quantum non-demolition (QND) measurement minimizes this disturbance by using a…

Superconductivity · Physics 2015-06-25 A. Lupascu , S. Saito , T. Picot , P. C. de Groot , C. J. P. M. Harmans , J. E. Mooij

This work extends the previous quantum projection filtering scheme in [Gao Q., Zhang G., & Petersen I. R. (2019). An exponential quantum projection filter for open quantum systems. \emph{Automatica}, 99, 59-68.], by adding an optimality…

Quantum Physics · Physics 2019-10-01 Qing Gao , Guofeng Zhang , Ian R. Petersen

The improvement of computed tomography (CT) image resolution is beneficial to the subsequent medical diagnosis, but it is usually limited by the scanning devices and great expense. Convolutional neural network (CNN)-based methods have…

Medical Physics · Physics 2019-03-26 Chao Tang , Wenkun Zhang , Ziheng Li , Ailong Cai , Linyuan Wang , Lei Li , Ningning Liang , Bin Yan

We introduce a method of quantum tomography for a continuous variable system in position and momentum space. We consider a single two-level probe interacting with a quantum harmonic oscillator by means of a class of Hamiltonians, linear in…

Quantum Physics · Physics 2015-03-19 J. Casanova , C. E. Lopez , J. J. Garcia-Ripoll , C. F. Roos , E. Solano

In quantum technologies, quantum channels are essential elements for the transmission of quantum states. The action of a quantum channel usually introduces noise in the quantum state and thereby reduces the information contained in it.…

Quantum Physics · Physics 2026-04-10 Arindam Mitra , Jatin Ghai

Nielsen [quant-ph/0108020] showed that universal quantum computation is possible given quantum memory and the ability to perform projective measurements on up to 4-qubits. We describe an improved method that requires only 2-qubit…

Quantum Physics · Physics 2007-05-23 D. W. Leung

Quantum circuits for loading probability distributions into quantum states are essential subroutines in quantum algorithms used in physics, finance engineering, and machine learning. The ability to implement these with high accuracy in…

Quantum Physics · Physics 2025-10-07 Yuichi Sano , Ikko Hamamura

The characterization of quantum processes is a key tool in quantum information processing tasks for several reasons: on one hand, it allows to acknowledge errors in the implementations of quantum algorithms; on the other, it allows to…

Quantum Physics · Physics 2018-12-12 Ignacio Perito , Augusto Roncaglia , Ariel Bendersky

Cone-beam computed tomography (CBCT) systems, with their flexibility, present a promising avenue for direct point-of-care medical imaging, particularly in critical scenarios such as acute stroke assessment. However, the integration of CBCT…

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