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Quantum state tomography, aimed at deriving a classical description of an unknown state from measurement data, is a fundamental task in quantum physics. In this work, we analyse the ultimate achievable performance of tomography of…

The measurement of a quantum state poses a unique challenge for experimentalists. Recently, the technique of "direct measurement" was proposed for characterizing a quantum state in-situ through sequential weak and strong measurements. While…

Spatial qudit states can be realized by using multi-slits to discretize the transverse momentum of a photon. The merit of this kind of spatial qudit states is that the implementation of higher dimensional qudits is relatively easy. As we…

Quantum Physics · Physics 2009-12-03 Gen Taguchi , Tatsuo Dougakiuchi , Masataka Iinuma , Holger F. Hofmann , Yutaka Kadoya

Advancements in quantum system lifetimes and control have enabled the creation of increasingly complex quantum states, such as those on multiple bosonic cavity modes. When characterizing these states, traditional tomography scales…

Quantum Physics · Physics 2023-09-20 Kevin He , Ming Yuan , Yat Wong , Srivatsan Chakram , Alireza Seif , Liang Jiang , David I. Schuster

In the paper the Bayesian and the least squares methods of quantum state tomography are compared for a single qubit. The quality of the estimates are compared by computer simulation when the true state is either mixed or pure. The fidelity…

Quantum Physics · Physics 2007-05-23 Th. Baier , K. M. Hangos , A. Magyar , D. Petz

The stabilization of quantum states is a fundamental problem for realizing various quantum technologies. Measurement-based-feedback strategies have demonstrated powerful performance, and the construction of quantum control signals using…

Systems and Control · Electrical Eng. & Systems 2026-04-10 Chunxiang Song , Yanan Liu , Daoyi Dong , Hidehiro Yonezawa

Quantum state tomography (QST) is a challenging task in intermediate-scale quantum devices. Here, we apply conditional generative adversarial networks (CGANs) to QST. In the CGAN framework, two duelling neural networks, a generator and a…

Quantum Physics · Physics 2021-10-04 Shahnawaz Ahmed , Carlos Sánchez Muñoz , Franco Nori , Anton Frisk Kockum

Quantum computers promise significant speedups in solving problems intractable for conventional computers but, despite recent progress, remain limited in scaling and availability. Therefore, quantum software and hardware development heavily…

Quantum Physics · Physics 2023-11-08 Stefan Hillmich , Igor L. Markov , Robert Wille

We propose a new quantum state reconstruction method that combines ideas from compressed sensing, non-convex optimization, and acceleration methods. The algorithm, called Momentum-Inspired Factored Gradient Descent (\texttt{MiFGD}), extends…

Quantum Physics · Physics 2022-03-24 Junhyung Lyle Kim , George Kollias , Amir Kalev , Ken X. Wei , Anastasios Kyrillidis

Quantum state tomography is a central technique for the characterization and verification of quantum systems. Standard tomography is widely used for low-dimensional systems, but for larger systems, it becomes impractical due to the…

Non-Gaussian quantum states are critical resources in photonic quantum information processing, rendering their generation and characterization of increasing importance in quantum optics. In this work, we theoretically and numerically…

Quantum Physics · Physics 2025-12-22 Rhea P. Fernandes , Andrew J. Pizzimenti , Christos N. Gagatsos , Joseph M. Lukens

In quantum information transformation and quantum computation, the most critical issues are security and accuracy. These features, therefore, stimulate research on quantum state characterization. A characterization tool, Quantum state…

Quantum Physics · Physics 2023-06-01 Xudan Chai , Teng Ma , Qihao Guo , Zhangqi Yin , Hao Wu , Qing Zhao

A longstanding belief in quantum tomography is that estimating a mixed state is far harder than estimating a pure state. This is borne out in the mathematics, where mixed state algorithms have always required more sophisticated techniques…

Quantum Physics · Physics 2025-11-21 Angelos Pelecanos , Jack Spilecki , Ewin Tang , John Wright

We present a simple yet efficient Hybrid Classifier based on Deep Learning and Reinforcement Learning. Q-Learning is used with two Q-states and four actions. Conventional techniques use feature maps extracted from Convolutional Neural…

Computer Vision and Pattern Recognition · Computer Science 2020-08-11 Abdul Mueed Hafiz , Ghulam Mohiuddin Bhat

We introduce an approach for performing quantum state reconstruction on systems of $n$ qubits using a machine-learning-based reconstruction system trained exclusively on $m$ qubits, where $m\geq n$. This approach removes the necessity of…

In order to leverage the full power of quantum noise squeezing with unavoidable decoherence, a complete understanding of the degradation in the purity of squeezed light is demanded. By implementing machine learning architecture with a…

Classical shadows are a computationally efficient approach to storing quantum states on a classical computer for the purposes of estimating expectation values of local observables, obtained by performing repeated random measurements. In…

Quantum Physics · Physics 2023-05-03 Saumya Shivam , C. W. von Keyserlingk , S. L. Sondhi

This letter proposes a fast implementation of the regularity-constrained discrete sine transform (R-DST). The original DST \textit{leaks} the lowest frequency (DC: direct current) components of signals into high frequency (AC: alternating…

Signal Processing · Electrical Eng. & Systems 2023-09-21 Taizo Suzuki , Seisuke Kyochi , Yuichi Tanaka

Estimation of quantum states and measurements is crucial for the implementation of quantum information protocols. The standard method for each is quantum tomography. However, quantum tomography suffers from systematic errors caused by…

Quantum Physics · Physics 2018-10-19 Adam C. Keith , Charles H. Baldwin , Scott Glancy , E. Knill

Quantum state tomography is the standard technique for reconstructing a quantum state from experimental data. In the regime of finite statistics, experimental data cannot give perfect information about the quantum state. A common way to…

Quantum Physics · Physics 2024-07-03 Carlos de Gois , Matthias Kleinmann