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Although robust learning and local differential privacy are both widely studied fields of research, combining the two settings is just starting to be explored. We consider the problem of estimating a discrete distribution in total variation…

Statistics Theory · Mathematics 2022-04-21 Julien Chhor , Flore Sentenac

We propose a learning method for estimating unknown pure quantum states. The basic idea of our method is to learn a unitary operation $\hat{U}$ that transforms a given unknown state $|\psi_\tau\rangle$ to a known fiducial state $|f\rangle$.…

Quantum Physics · Physics 2018-11-07 Sang Min Lee , Jinhyoung Lee , Jeongho Bang

A fundamental problem in statistics and learning theory is to test properties of distributions. We show that quantum computers can solve such problems with significant speed-ups. In particular, we give fast quantum algorithms for testing…

Quantum Physics · Physics 2019-02-05 András Gilyén , Tongyang Li

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 show that in device independent quantum key distribution protocols the privacy of randomness is of crucial importance. For sublinear test sample sizes even the slightest guessing probability by an eavesdropper will completely compromise…

Quantum Physics · Physics 2013-09-12 Marcus Huber , Marcin Pawlowski

Measurements of quantum states form a key component in quantum-information processing. It is therefore an important task to compare measurements and furthermore decide if a measurement strategy is optimal. Entropic quantities, such as the…

Quantum Physics · Physics 2023-05-17 Wilfred Salmon , Sergii Strelchuk , David Arvidsson-Shukur

Quantum metrology aims to exploit quantum phenomena to overcome classical limitations in the estimation of relevant parameters. We consider a probe undergoing a phase shift $\varphi$ whose generator is randomly sampled according to a…

Quantum Physics · Physics 2017-06-07 Rozhin Yousefjani , Rosanna Nichols , Shahriar Salimi , Gerardo Adesso

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

The goal of self-testing is to characterize an a priori unknown quantum system based solely on measurement statistics, i.e. using an uncharacterized measurement device. Here we develop self-testing methods for quantum prepare-and-measure…

Quantum Physics · Physics 2018-12-10 Armin Tavakoli , Jędrzej Kaniewski , Tamás Vértesi , Denis Rosset , Nicolas Brunner

We establish connections between state tomography, pseudorandomness, quantum state synthesis, and circuit lower bounds. In particular, let $\mathfrak{C}$ be a family of non-uniform quantum circuits of polynomial size and suppose that there…

Quantum Physics · Physics 2025-09-26 Nai-Hui Chia , Daniel Liang , Fang Song

We study the sample complexity of the prototypical tasks quantum purity estimation and quantum inner product estimation. In purity estimation, we are to estimate $tr(\rho^2)$ of an unknown quantum state $\rho$ to additive error $\epsilon$.…

Quantum Physics · Physics 2024-10-17 Weiyuan Gong , Jonas Haferkamp , Qi Ye , Zhihan Zhang

A statistical distinguishability based on relative entropy characterises the fitness of quantum states for phase estimation. This criterion is employed in the context of a Mach-Zehnder interferometer and used to interpolate between two…

Quantum Physics · Physics 2009-11-13 Gabriel A. Durkin , Jonathan P. Dowling

Quantum speed limits are usually regarded as fundamental restrictions, constraining the amount of computation that can be achieved within some given time and energy. Complementary to this intuition, here we show that these limitations are…

Quantum Physics · Physics 2026-03-12 Caroline L. Jones , Albert Aloy , Gerard Higgins , Markus P. Mueller

Fidelity estimation for entangled states constitutes an essential building block for quality control and error detection in quantum networks. Nonetheless, quantum networks often encounter heterogeneous and correlated noise, leading to…

Quantum Physics · Physics 2024-11-18 Liangzhong Ruan , Bas Dirkse

Quantum tomography is the main method used to assess the quality of quantum information processing devices, but its complexity presents a major obstacle for the characterization of even moderately large systems. The number of experimental…

Quantum Physics · Physics 2015-03-19 Marcus P. da Silva , Olivier Landon-Cardinal , David Poulin

Entanglement, and quantum correlation, are precious resources for quantum technologies implementation based on quantum information science, such as, for instance, quantum communication, quantum computing, and quantum interferometry.…

Quantum Physics · Physics 2023-05-22 Arthur Vesperini , Ghofrane Bel-Hadj-Aissa , Roberto Franzosi

The impact of measurement imperfections on quantum metrology protocols has not been approached in a systematic manner so far. In this work, we tackle this issue by generalising firstly the notion of quantum Fisher information to account for…

Quantum Physics · Physics 2022-11-21 Yink Loong Len , Tuvia Gefen , Alex Retzker , Jan Kołodyński

We revisit the basic problem of quantum state certification: given copies of unknown mixed state $\rho\in\mathbb{C}^{d\times d}$ and the description of a mixed state $\sigma$, decide whether $\sigma = \rho$ or $\|\sigma -…

Quantum Physics · Physics 2021-11-12 Sitan Chen , Jerry Li , Ryan O'Donnell

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…

Efficient estimation of nonlinear functions of quantum states is crucial for various key tasks in quantum computing, such as entanglement spectroscopy, fidelity estimation, and feature analysis of quantum data. Conventional methods using…

Quantum Physics · Physics 2025-06-23 Hongshun Yao , Yingjian Liu , Tengxiang Lin , Xin Wang