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Related papers: Practical Homodyne Shadow Estimation

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The classical shadows protocol, introduced by Huang et al. [Nat. Phys. 16, 1050 (2020)], makes use of the median-of-means (MoM) estimator to efficiently estimate the expectation values of $M$ observables with failure probability $\delta$…

Quantum Physics · Physics 2025-06-25 Winston Fu , Dax Enshan Koh , Siong Thye Goh , Jian Feng Kong

A traditional heterodyne detector, as a phase-insensitive device, suffers the well-known 3 dB noise penalty caused by image sideband vacuum. In contrast, a heterodyne detector with a bichromatic local oscillator, as a phase-sensitive…

Quantum Physics · Physics 2015-06-25 Sheng Feng , Dechao He , Heng Fan

The measurement problem for the optical phase has been traditionally attacked for noiseless schemes or in the presence of amplitude or detection noise. Here we address estimation of phase in the presence of phase diffusion and evaluate the…

Quantum Physics · Physics 2015-03-17 Marco G. Genoni , Stefano Olivares , Matteo G. A. Paris

Classical shadows provide a versatile framework for estimating many properties of quantum states from repeated, randomly chosen measurements without requiring full quantum state tomography. When prior information is available, such as…

Quantum Physics · Physics 2026-05-27 Jacob Bringewatt , Henry Froland , Andreas Elben , Niklas Mueller

We study the sample complexity of shadow tomography in the high-precision regime under realistic measurement constraints. Given an unknown $d$-dimensional quantum state $\rho$ and a known set of observables $\{O_i\}_{i=1}^m$, the goal is to…

Quantum Physics · Physics 2026-02-06 Senrui Chen , Weiyuan Gong , Sisi Zhou

We present an experimental demonstration of the power of real-time feedback in quantum metrology, confirming a theoretical prediction by Wiseman regarding the superior performance of an adaptive homodyne technique for single-shot…

Quantum Physics · Physics 2007-05-23 Michael A. Armen , John K. Au , John K. Stockton , Andrew C. Doherty , Hideo Mabuchi

Quantum state readout serves as the cornerstone of quantum information processing, exerting profound influence on quantum communication, computation, and metrology. In this study, we introduce an innovative readout architecture called…

Quantum Physics · Physics 2023-12-21 Chen Ding , Xiao-Yue Xu , Shuo Zhang , Wan-Su Bao , He-Liang Huang

Quantum process tomography (QPT) is crucial for advancing quantum technologies, including quantum computers, quantum networks and quantum sensors. Shadow process tomography (SPT) utilizes the Choi isomorphism to map QPT to shadow state…

Quantum Physics · Physics 2025-07-16 Haigang Wang , Kan He

Quantum trajectories describe the stochastic evolution of an open quantum system conditioned on continuous monitoring of its output, such as by an ideal photodetector. Here we derive (non-Markovian) quantum trajectories for realistic…

Quantum Physics · Physics 2009-11-07 P. Warszawski , H. M. Wiseman , H. Mabuchi

Quantum trajectories describe the stochastic evolution of an open quantum system conditioned on continuous monitoring of its output, such as by an ideal photodetector. In practice an experimenter has access to an output filtered through…

Quantum Physics · Physics 2016-09-08 P. Warszawski , H. M. Wiseman

Classical shadows are an efficient method for constructing an approximate classical description of a quantum state using very few measurements. In the paper we propose to enhance classical shadow methods using bootstrap resampling methods.…

Quantum Physics · Physics 2025-11-18 Eric Ghysels , Jack Morgan

Randomised measurements can efficiently characterise many-body quantum states by learning the expectation values of observables with low Pauli weights. In this paper, we generalise the theoretical tools of classical shadow tomography to the…

Quantum Physics · Physics 2026-02-05 Gregory A. L. White , Lloyd C. L. Hollenberg , Charles D. Hill , Kavan Modi

Digital signatures guarantee the authorship of electronic communications. Currently used "classical" signature schemes rely on unproven computational assumptions for security, while quantum signatures rely only on the laws of quantum…

It is believed that the quantum behaviors of homodyne detectors and traditional heterodyne detectors can be fully understood in the context of the quantum theory of optical detection. According to the theory, a 3 dB extra quantum noise has…

Quantum Physics · Physics 2015-10-28 Heng Fan , Dechao He , Sheng Feng

We address parameter estimation for complex/structured systems and suggest an effective estimation scheme based on continuous-variables quantum probes. In particular, we investigate the use of a single bosonic mode as a probe for Ohmic…

Quantum Physics · Physics 2018-01-31 Matteo Bina , Federico Grasselli , Matteo G. A. Paris

In comparison to conventional discrete-variable (DV) quantum key distribution (QKD), continuous-variable (CV) QKD with homodyne/heterodyne measurements has distinct advantages of lower-cost implementation and affinity to wavelength division…

Quantum Physics · Physics 2021-01-18 Takaya Matsuura , Kento Maeda , Toshihiko Sasaki , Masato Koashi

We present an analysis of the time domain measurement of temporally resolvable quantum states using balanced homodyne detection. Our approach outlines a formalism of detecting quantum states in arbitrary temporal modes via projection of the…

Quantum Physics · Physics 2026-02-17 Owen Sandner , Brendan Mackey , Yuyang Liu , Connor Kupchak , Andrew MacRae

Estimating the fidelity between a desired target quantum state and an actual prepared state is essential for assessing the success of experiments. For pure target states, we use functional representations that can be measured directly and…

Quantum Physics · Physics 2024-09-09 Omar Fawzi , Aadil Oufkir , Robert Salzmann

This paper presents a survey and a comparative evaluation of recent techniques for moving cast shadow detection. We identify shadow removal as a critical step for improving object detection and tracking. The survey covers methods published…

Computer Vision and Pattern Recognition · Computer Science 2013-04-05 Andres Sanin , Conrad Sanderson , Brian C. Lovell

The accurate state estimation of unknown bodies in space is a critical challenge with applications ranging from the tracking of space debris to the shape estimation of small bodies. A necessary enabler to this capability is to find and…

Computer Vision and Pattern Recognition · Computer Science 2025-08-06 Arion Zimmermann , Soon-Jo Chung , Fred Hadaegh