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Quantum sensing harnesses the unique properties of quantum systems to enable precision measurements of physical quantities such as time, magnetic and electric fields, acceleration, and gravitational gradients well beyond the limits of…

Quantum Physics · Physics 2025-07-23 Ivana Nikoloska , Ruud Van Sloun , Osvaldo Simeone

Scalable characterization of quantum processors is crucial for mitigating noise and imperfections. While randomized measurement protocols enable efficient access to local observables, inferring a globally consistent description of…

Quantum Physics · Physics 2026-03-10 Zidu Liu , Dominik S. Wild

We study supervised learning algorithms in which a quantum device is used to perform a computational subroutine - either for prediction via probability estimation, or to compute a kernel via estimation of quantum states overlap. We design…

Quantum Physics · Physics 2021-07-07 Ulysse Chabaud , Damian Markham , Adel Sohbi

We establish the necessary and sufficient conditions for unbiased estimation in multi-parameter estimation tasks. More specifically, we first consider quantum state estimation, where multiple parameters are encoded in a quantum state, and…

Quantum Physics · Physics 2026-03-03 Hyukgun Kwon , Kento Tsubouchi , Chia-Tung Chu , Liang Jiang

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

Unitary Coupled Cluster (UCC) approaches are an appealing route to utilising quantum hardware to perform quantum chemistry calculations, as quantum computers can in principle perform UCC calculations in a polynomially scaling fashion, as…

Quantum Physics · Physics 2022-06-15 Maria-Andreea Filip , Nathan Fitzpatrick , David Muñoz Ramo , Alex J. W. Thom

We propose a quantum machine learning algorithm for efficiently solving a class of problems encoded in quantum controlled unitary operations. The central physical mechanism of the protocol is the iteration of a quantum time-delayed equation…

We introduce a new quantum noise deconvolution technique that does not rely on the complete knowledge of noise and does not require partial noise tomography. In this new method, we construct a set of observables with completely correctable…

Quantum Physics · Physics 2025-06-10 Nahid Ahmadvand , Laleh Memarzadeh

Learning many-body quantum states and quantum phase transitions remains a major challenge in quantum many-body physics. Classical machine learning methods offer certain advantages in addressing these difficulties. In this work, we propose a…

Quantum Physics · Physics 2026-02-03 Xin Li , Zhang-Qi Yin

Deep learning has seen substantial achievements, with numerical and theoretical evidence suggesting that singularities of statistical models are considered a contributing factor to its performance. From this remarkable success of classical…

Quantum Physics · Physics 2024-11-26 Hiroshi Yano , Yota Maeda , Naoki Yamamoto

Efficient fidelity estimation of multiqubit quantum states is crucial to many applications in quantum information processing. However, to estimate the infidelity $\epsilon$ with multiplicative precision, conventional estimation protocols…

Quantum Physics · Physics 2025-12-01 Zhongyi Yang , Datong Chen , Zihao Li , Huangjun Zhu

"Classical shadows" are estimators of an unknown quantum state, constructed from suitably distributed random measurements on copies of that state [Nature Physics 16, 1050-1057]. Here, we analyze classical shadows obtained using random…

Quantum Physics · Physics 2023-11-28 Kianna Wan , William J. Huggins , Joonho Lee , Ryan Babbush

Contrastive representation learning has proven to be an effective self-supervised learning method for images and videos. Most successful approaches are based on Noise Contrastive Estimation (NCE) and use different views of an instance as…

Computer Vision and Pattern Recognition · Computer Science 2023-09-27 Julien Denize , Jaonary Rabarisoa , Astrid Orcesi , Romain Hérault

Communication over a random-parameter quantum channel when the decoder is required to reconstruct the parameter sequence is considered. We study scenarios that include either strictly-causal, causal, or non-causal channel side information…

Information Theory · Computer Science 2021-09-28 Uzi Pereg

Classical shadows are succinct classical representations of quantum states which allow one to encode a set of properties P of a quantum state rho, while only requiring measurements on logarithmically many copies of rho in the size of P. In…

Quantum Physics · Physics 2026-05-28 Georgios Karaiskos , Dorian Rudolph , Johannes Jakob Meyer , Jens Eisert , Sevag Gharibian

This paper investigates the mean square error (MSE)-optimal conditional mean estimator (CME) in one-bit quantized systems in the context of channel estimation with jointly Gaussian inputs. We analyze the relationship of the generally…

Information Theory · Computer Science 2023-06-28 Benedikt Fesl , Michael Koller , Wolfgang Utschick

The current generation of quantum computing technologies call for quantum algorithms that require a limited number of qubits and quantum gates, and which are robust against errors. A suitable design approach are variational circuits where…

Quantum Physics · Physics 2020-04-10 Maria Schuld , Alex Bocharov , Krysta Svore , Nathan Wiebe

For a continuous-input-continuous-output arbitrarily distributed quantum channel carrying classical information, the channel capacity can be computed in terms of the distribution of the channel envelope, received signal strength over a…

Information Theory · Computer Science 2022-06-09 Mouli Chakraborty , Harun Siljak , Indrakshi Dey , Nicola Marchetti

This note studies a method for the efficient estimation of a finite number of unknown parameters from linear equations, which are perturbed by Gaussian noise. In case the unknown parameters have only few nonzero entries, the proposed…

Systems and Control · Computer Science 2014-05-27 Liang Dai , Kristiaan Pelckmans

We address the use of a single qubit as a quantum probe to characterize the properties of classical noise. In particular, we focus on the characterization of classical noise arising from the interaction with a stochastic field described by…

Quantum Physics · Physics 2015-10-07 Claudia Benedetti , Matteo G. A. Paris