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We propose a method for precision statistical control of quantum processes based on superconductor phase qubits. Using the universal quantum tomography method, we provide a detailed analysis of accuracy of tomography for a 2-qubit gate…

Quantum Physics · Physics 2017-07-26 Yu. I. Bogdanov , S. A. Nuyanzin

We propose a protocol for solving systems of linear algebraic equations via quantum mechanical methods using the minimal number of qubits. We show that $(M+1)$-qubit system is enough to solve a system of $M$ equations for one of the…

Quantum Physics · Physics 2020-01-03 S. I. Doronin , E. B. Fel'dman , A. I. Zenchuk

Quantum process tomography conventionally uses a multitude of initial quantum states and then performs state tomography on the process output. Here we propose and study an alternative approach which requires only a single (or few) known…

Quantum Physics · Physics 2023-11-09 Irene López Gutiérrez , Felix Dietrich , Christian B. Mendl

While quantum computing provides an exponential advantage in solving system of linear equations, there is little work to solve system of nonlinear equations with quantum computing. We propose quantum Newton's method (QNM) for solving…

Quantum Physics · Physics 2025-12-29 Cheng Xue , Yu-Chun Wu , Guo-Ping Guo

We show that a general linear transformation from one single photon qudit to another, the dimension of which can be either equal or unequal to that of the first one, can be implemented by linear optics. As an application of the scheme we…

Quantum Physics · Physics 2007-10-22 Bing He , János A. Bergou , Zhiyong Wang

Quantum process tomography is a critical capability for building quantum computers, enabling quantum networks, and understanding quantum sensors. Like quantum state tomography, the process tomography of an arbitrary quantum channel requires…

Quantum Physics · Physics 2023-05-26 Jonathan Kunjummen , Minh C. Tran , Daniel Carney , Jacob M. Taylor

Quantum state tomography (QST) for reconstructing pure states requires exponentially increasing resources and measurements with the number of qubits by using state-of-the-art quantum compressive sensing (CS) methods. In this article, QST…

Quantum Physics · Physics 2021-11-16 Burhan Gulbahar

A central task in quantum information processing is to characterize quantum processes. In the realm of optical quantum information processing, this amounts to characterizing the transformations of the mode creation and annihilation…

Quantum Physics · Physics 2018-11-28 Kevin Valson Jacob , Anthony E. Mirasola , Sushovit Adhikari , Jonathan P. Dowling

Spectroscopy underpins modern scientific discovery across diverse disciplines. While experimental spectroscopy probes material properties through scattering or radiation measurements, computational spectroscopy combines theoretical models…

A new qubit tomography protocol is introduced, based on a continuous positive operator valued measure, which is supported by the set of pure states, and equivariant under the symmetry group SO(3,R) of the qubit state space. Thus the sample…

Quantum Physics · Physics 2008-03-14 Tamás Tasnádi

Reconstructing quantum states from measurement data represents a formidable challenge in quantum information science, especially as system sizes grow beyond the reach of traditional tomography methods. While recent studies have explored…

Quantum Physics · Physics 2026-04-06 Shabnam Jabeen , Dmytro Kurdydyk , Aadi Palnitkar , Mihir Talati , Jeffrey Yan , Jinghong Yang

We investigate two-way and one-way single-photon quantum key distribution (QKD) protocols in the presence of loss introduced by the quantum channel. Our analysis is based on a simple precondition for secure QKD in each case. In particular,…

Quantum Physics · Physics 2009-11-13 Marcos Curty , Tobias Moroder

At large scales, quantum systems may become advantageous over their classical counterparts at performing certain tasks. Developing tools to analyse these systems at the relevant scales, in a manner consistent with quantum mechanics, is…

Quantum Physics · Physics 2024-11-12 Timon Schapeler , Robert Schade , Michael Lass , Christian Plessl , Tim J. Bartley

Recent progress in characterization for gapped quantum phases has also triggered the search of universal resource for quantum computation in symmetric gapped phases. Prior works in one dimension suggest that it is a feature more common than…

Quantum Physics · Physics 2017-09-18 Tzu-Chieh Wei , Ching-Yu Huang

In the current work we address the problem of quantum process tomography (QPT) in the case of imperfect preparation and measurement of the states which are used for QPT. The fuzzy measurements approach which helps us to efficiently take…

Quantum Physics · Physics 2019-03-21 B. I. Bantysh , D. V. Fastovets , Yu. I. Bogdanov

In this work, we present two new methods for Variational Quantum Circuit (VQC) Process Tomography onto $n$ qubits systems: PT_VQC and U-VQSVD. Compared to the state of the art, PT_VQC halves in each run the required amount of qubits for…

Quantum Physics · Physics 2024-07-12 Vladlen Galetsky , Pol Julià Farré , Soham Ghosh , Christian Deppe , Roberto Ferrara

We propose an iterative algorithm for incomplete quantum process tomography, with the help of quantum state estimation, based on the combined principles of maximum-likelihood and maximum-entropy. The algorithm yields a unique estimator for…

Quantum Physics · Physics 2012-01-04 Yong Siah Teo , Berthold-Georg Englert , Jaroslav Rehacek , Zdenek Hradil

Transition Path Theory (TPT) provides a rigorous framework to investigate the dynamics of rare thermally activated transitions. In this theory, a central role is played by the forward committor function q^+(x), which provides the ideal…

Statistical Mechanics · Physics 2018-08-15 G. Bartolucci , S. Orioli , P. Faccioli

Quantum tomography makes it possible to obtain comprehensive information about certain logical elements of a quantum computer. In this regard, it is a promising tool for debugging quantum computers. The practical application of tomography,…

Quantum Physics · Physics 2020-12-23 B. I. Bantysh , Yu. I. Bogdanov

Quantum tomography is a cornerstone of quantum information science, enabling the reconstruction of states and channels from experimental data. Here we introduce a new paradigm, temporal state tomography (TST), for reconstructing quantum…

Quantum Physics · Physics 2026-05-05 Zhian Jia