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Characterizing and mitigating errors in current noisy intermediate-scale devices is important to improve performance of next generations of quantum hardware. In order to investigate the importance of the different noise mechanisms affecting…

Quantum Physics · Physics 2023-02-14 Gabriele Cenedese , Giuliano Benenti , Maria Bondani

Critical phenomena of quantum systems offer a promising strategy to improve measurement precision. So far, many criticality-enhanced quantum metrological schemes have been proposed by using the adiabatically evolved photonic states of…

Quantum Physics · Physics 2026-03-31 Ken Chen , Jia-Hao Lv , Wen Ning , Zhen-Biao Yang , Shi-Biao Zheng

Entanglement lies at the core of quantum algorithms designed to solve problems that are intractable by classical approaches. One such algorithm, quantum annealing (QA), provides a promising path to a practical quantum processor. We have…

This paper is one of a series of papers on coherent spaces and their applications, defined in the recent book 'Coherent Quantum Mechanics' by the first author. The paper studies coherent quantization -- the way operators in the quantum…

Mathematical Physics · Physics 2022-02-08 Arnold Neumaier , Arash Ghaani Farashahi

We re-examine a non-Gaussian quantum error correction code designed to protect optical coherent-state qubits against errors due to an amplitude damping channel. We improve on a previous result [Phys. Rev. A 81, 062344 (2010)] by providing a…

Quantum Physics · Physics 2014-05-14 Ricardo Wickert , Peter van Loock

A random field that is empirically equivalent to the quantized electromagnetic field is constructed. A mapping between the creation and annihilation operator algebras of a random field and of the quantized electromagnetic field provides a…

Quantum Physics · Physics 2011-10-11 Peter Morgan

The purpose of this paper is to study and design direct and indirect couplings for use in coherent feedback control of a class of linear quantum stochastic systems. A general physical model for a nominal linear quantum system coupled…

Quantum Physics · Physics 2012-02-07 Guofeng Zhang , Matthew R. James

The purpose of this paper is to investigate system identification for single-input-single-output general (active or passive) quantum linear systems. For a given input we address the following questions: (1) Which parameters can be…

Quantum Physics · Physics 2017-12-25 Matthew Levitt , Madalin Guta

We calculate the noise spectrum of the output signal of a quantum detector during continuous measurement of a two-level system (qubit). We generalize the previous results obtained for the regime of high voltages (when $eV$ is much larger…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 A. Shnirman , D. Mozyrsky , I. Martin

We study continuous variable systems, in which quantum and classical degrees of freedom are combined and treated on the same footing. Thus all systems, including the inputs or outputs to a channel, may be quantum-classical hybrids. This…

Quantum Physics · Physics 2023-07-26 Lars Dammeier , Reinhard F. Werner

Quantum entanglement is known as a unique feature of quantum mechanics, which cannot be obtained from classical physics. Recently, a coherence interpretation has been conducted for the delayed-choice quantum eraser using coherent photon…

Quantum Physics · Physics 2022-11-22 Byoung S. Ham

The Heisenberg uncertainty principle imposes a fundamental restriction in quantum mechanics, stipulating that measuring one observable completely erases the information on its conjugate one, thereby preventing simultaneous measurements of…

Quantum Physics · Physics 2026-01-19 Muchun Yang , Yibin Huang , D. L. Zhou

We investigate the quantization of a free particle coupled linearly to a harmonic oscillator. This system, whose classical counterpart has clearly separated regular and chaotic regions, provides an ideal framework for studying the…

Chaotic Dynamics · Physics 2009-11-13 Thomas Mainiero , Mason A. Porter

The relation between the dynamical properties of a coupled quasiparticle-oscillator system in the mixed quantum-classical and fully quantized descriptions is investigated. The system is considered to serve as a model system for applying a…

chao-dyn · Physics 2009-10-28 Holger Schanz , Bernd Esser

This paper studies quantum limits to dynamical sensors in the presence of decoherence. A modified purification approach is used to obtain tighter quantum detection and estimation error bounds for optical phase sensing and optomechanical…

Quantum Physics · Physics 2013-07-04 Mankei Tsang

A structural explanation of the coupling constants in the standard model, i.e the fine structure constant and the Weinberg angle, and of the gauge fixing contributions is given in terms of symmetries and representation theory. The coupling…

Quantum Physics · Physics 2008-11-26 H. Saller , R. Breuninger , M. Haft

A direct classical analog of quantum decoherence is introduced. Similarities and differences between decoherence dynamics examined quantum mechanically and classically are exposed via a second-order perturbative treatment and via a strong…

Quantum Physics · Physics 2009-11-07 Jiangbin Gong , Paul Brumer

Viewed as approximations to quantum mechanics, classical evolutions can violate the positive-semidefiniteness of the density matrix. The nature of this violation suggests a classification of dynamical systems based on classical-quantum…

Quantum Physics · Physics 2009-11-06 Salman Habib , Kurt Jacobs , Hideo Mabuchi , Robert Ryne , Kosuke Shizume , Bala Sundaram

A direct coupling coherent observer is constructed for a linear quantum plant which has oscillatory solutions. It is shown that a finite time moving average of the quantum observer output can provide an estimate of the quantum plant output…

Quantum Physics · Physics 2017-06-21 Ian R. Petersen

An active area of investigation in the search for quantum advantage is Quantum Machine Learning. Quantum Machine Learning, and Parameterized Quantum Circuits in a hybrid quantum-classical setup in particular, could bring advancements in…

Quantum Physics · Physics 2020-09-01 Thomas Hubregtsen , Josef Pichlmeier , Patrick Stecher , Koen Bertels