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Quantum sensing encompasses highly promising techniques with diverse applications including noise-reduced imaging, super-resolution microscopy as well as imaging and spectroscopy in challenging spectral ranges. These detection schemes use…

Quantum Physics · Physics 2022-11-23 Felix Riexinger , Mirco Kutas , Björn Haase , Michael Bortz , Georg von Freymann

Projective measurements are a powerful tool for manipulating quantum states. In particular, a set of qubits can be entangled by measurement of a joint property such as qubit parity. These joint measurements do not require a direct…

Until recently, a quantum instrument was defined to be a completely positive operation-valued measure from the set of states on a Hilbert space to itself. In the last few years, this definition has been generalized to such measures between…

Quantum Physics · Physics 2023-06-08 Stanley Gudder

We investigate the compression of quantum information with respect to a given set $\mathcal{M}$ of high-dimensional measurements. This leads to a notion of simulability, where we demand that the statistics obtained from $\mathcal{M}$ and an…

Classical simulations of noisy quantum circuits are instrumental to our understanding of the behavior of real-world quantum systems and the identification of regimes where one expects quantum advantage. In this work, we present a highly…

Quantum Physics · Physics 2026-02-17 Simon Cichy , Paul K. Faehrmann , Lennart Bittel , Jens Eisert , Hakop Pashayan

We address the use of entangled qubits as quantum probes to characterize the noise induced by complex environments. In particular, we show that a joint measurement on entangled probes can improve estimation of the correlation time for a…

Quantum Physics · Physics 2017-11-07 Matteo A. C. Rossi , Matteo G. A. Paris

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

Quantum instruments are mathematical devices introduced to describe the conditional state change during a quantum process. They are completely positive map valued measures on measurable spaces. We may also view them as non-commutative…

Operator Algebras · Mathematics 2025-09-17 B. V. Rajarama Bhat , Arghya Chongdar , Sruthymurali

Noisy unsharp measurements incorporated in quantum information protocols may hinder performance, reducing the quantum advantage. However, we show that, unlike projective measurements which completely destroy quantum correlations between…

Quantum Physics · Physics 2025-07-01 Sudipta Mondal , Pritam Halder , Amit Kumar Pal , Aditi Sen De

In Ref. [Phys. Rev. A 100, 062317 (2019)], the authors reported an algorithm to implement, in a circuit-based quantum computer, a general quantum measurement (GQM) of a two-level quantum system, a qubit. Even though their algorithm seems…

Quantum Physics · Physics 2023-02-10 Douglas F. Pinto , Marcelo S. Zanetti , Marcos L. W. Basso , Jonas Maziero

In principle a quantum system could be used to simulate another quantum system. The purpose of such a simulation would be to obtain information about problems which cannot be simulated with a classical computer due to the exponential…

Quantum Physics · Physics 2013-05-30 Nayeli Zuniga-Hansen , Yu-Chieh Chi , Mark S. Byrd

Analog and digital quantum simulators can efficiently simulate quantum many-body systems that appear in natural phenomena. However, experimental limitations of near-term devices still make it challenging to perform the entire process of…

Quantum Physics · Physics 2024-09-13 Hideaki Hakoshima , Suguru Endo , Kaoru Yamamoto , Yuichiro Matsuzaki , Nobuyuki Yoshioka

In this paper we introduce a novel noise model for quantum measurements motivated by an indirect measurement scheme with faulty preparation. Averaging over random dynamics governing the interaction between the quantum system and a probe, a…

Quantum Physics · Physics 2025-07-17 Faedi Loulidi , Ion Nechita , Clément Pellegrini

The speed-up provided by quantum algorithms with respect to their classical counterparts is at the origin of scientific interest in quantum computation. However, the fundamental reasons for such a speed-up are not yet completely understood…

Quantum Physics · Physics 2007-05-23 C. Di Franco , M. Paternostro , M. S. Kim

Quantum instruments describe both the classical output and the updated quantum state in a measurement process. To do this in a non-trivial way, instruments must have the capability to interact coherently with the state that they measure.…

Quantum Physics · Physics 2026-03-31 Chung-Yun Hsieh , Armin Tavakoli , Huan-Yu Ku , Paul Skrzypczyk

In quantum theory general measurements are described by so-called Positive Operator-Valued Measures (POVMs). We show that in $d$-dimensional quantum systems an application of depolarizing noise with constant (independent of $d$) visibility…

Quantum Physics · Physics 2025-01-17 Michał Kotowski , Michał Oszmaniec

Owing to the computational complexity of electronic structure algorithms running on classical digital computers, the range of molecular systems amenable to simulation remains tightly circumscribed even after many decades of work. Quantum…

Quantum Physics · Physics 2022-05-18 Alexis Ralli , Michael I. Williams , Peter V. Coveney

We demonstrate that quantum instruments can provide a unified operational foundation for quantum theory. Since these instruments directly correspond to laboratory devices, this foundation provides an alternate, more experimentally grounded,…

Quantum Physics · Physics 2013-08-13 Justin Dressel , Andrew N. Jordan

Quantum sensing, using quantum properties of sensors, can enhance resolution, precision, and sensitivity of imaging, spectroscopy, and detection. An intriguing question is: Can the quantum nature (quantumness) of sensors and targets be…

Quantum Physics · Physics 2020-11-30 Ping Wang , Chong Chen , Renbao Liu

Quantum annealing is a type of analog computation that aims to use quantum mechanical fluctuations in search of optimal solutions of QUBO (quadratic unconstrained binary optimization) or, equivalently, Ising problems. Since NP-hard problems…

Quantum Physics · Physics 2023-04-14 Elijah Pelofske , Georg Hahn , Hristo N. Djidjev