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Measuring a quantum system can randomly perturb its state. The strength and nature of this back-action depends on the quantity which is measured. In a partial measurement performed by an ideal apparatus, quantum physics predicts that the…

Coherent feedback stabilises a system towards a target state without the need of a measurement, thus avoiding the quantum backaction inherent to measurements. Here, we employ optical coherent feedback to remotely cool a nanomechanical…

In this paper, we investigate non-Markovian quantum dynamics from the perspective of quantum noises in a network of atoms mediated by a waveguide. In such networks, quantum coherent feedback control becomes achievable when coherent fields…

Quantum Physics · Physics 2026-04-14 Haijin Ding , Guofeng Zhang

The purpose of this paper is to propose quantum filters for a two-level atom driven by two continuous-mode counter-propagating photons and under continuous measurements. Two scenarios of multiple measurements, 1) homodyne detection plus…

Quantum Physics · Physics 2019-03-14 Zhiyuan Dong , Guofeng Zhang , Nina H. Amini

We study the Markovian and Non-Markovian dynamics in a giant atom system which couples to a coupled resonator waveguide (CRW) via two distant sites. Under certain conditions, we find that the giant atom population can exhibit an oscillating…

Quantum Physics · Physics 2023-07-13 Xiaojun Zhang , Chengge Liu , Zhirui Gong , Zhihai Wang

We present a scheme for achieving broadband complete reflection by constructing photonic bandgap via collective atom-atom interaction in a one-dimensional (1D) waveguide quantum electrodynamics (QED) system. Moreover, we propose several…

Quantum Physics · Physics 2024-12-13 Xin Wang , Junjun He , Zeyang Liao , M. Suhail Zubairy

Quantum engineering using photonic structures offer new capabilities for atom-photon interactions for quantum optics and atomic physics, which could eventually lead to integrated quantum devices. Despite the rapid progress in the variety of…

Quantum Physics · Physics 2020-10-21 Wui Seng Leong , Mingjie Xin , Zilong Chen , Shijie Chai , Yu Wang , Shau-Yu Lan

Entangled systems with large quantum Fisher information (QFI) can be used to outperform the standard quantum limit of the separable systems in quantum metrology. However, the interaction between the system and the environments inevitably…

Quantum Physics · Physics 2016-08-23 Guofeng Zhang , Hanjie Zhu

We consider using Hamiltonian feedback control to increase the speed at which a continuous measurement purifies (reduces) the state of a quantum system, and thus to increase the speed of the preparation of pure states. For a measurement of…

Quantum Physics · Physics 2009-08-15 Joshua Combes , Kurt Jacobs

In variational quantum algorithms (VQAs), the most common objective is to find the minimum energy eigenstate of a given energy Hamiltonian. In this paper, we consider the general problem of finding a sufficient control Hamiltonian structure…

We study the dissipative dynamics of an atom in a V-level configuration driven by lasers and coupled to a semi-infinite waveguide. The coupling to the waveguide is chiral, in that each transition interacts only with the modes propagating in…

Quantum Physics · Physics 2016-09-21 Pierre-Olivier Guimond , Hannes Pichler , Arno Rauschenbeutel , Peter Zoller

We describe the light-matter interaction of a single two level atom with the electromagnetic vacuum in terms of field and dipole variables by considering homodyne detection of the emitted fields. Spontaneous emission is then observed as a…

Quantum Physics · Physics 2007-05-23 Holger F. Hofmann , Ortwin Hess , Guenter Mahler

The engineering and control of devices at the quantum-mechanical level--such as those consisting of small numbers of atoms and photons--is a delicate business. The fundamental uncertainty that is inherently present at this scale manifests…

Probability · Mathematics 2009-05-02 Luc Bouten , Ramon van Handel , Matthew R. James

We study several examples from quantum control theory in the framework of Wigner functions and measures for infinite dimensional open quantum systems. An axiomatic definition of coherent quantum feedback is proposed within this setting.

Mathematical Physics · Physics 2015-05-11 J. E. Gough , T. S. Ratiu , O. G. Smolyanov

We investigate the spontaneous emission of a two-level system, e.g. an atom or atomlike object, coupled to a single-end, i.e., semi-infinite, one-dimensional photonic waveguide such that one end behaves as a perfect mirror while light can…

Quantum Physics · Physics 2013-01-23 T. Tufarelli , F. Ciccarello , M. S. Kim

We develop a unified theoretical framework for the efficient description of multiphoton states generated and propagating in loop-based optical networks which contain nonlinear elements. These active optical components are modeled as…

Quantum Physics · Physics 2020-08-24 M. Engelkemeier , L. Lorz , Syamsundar De , B. Brecht , I. Dhand , M. B. Plenio , C. Silberhorn , J. Sperling

We investigate the scattering processes of two photons in a one-dimensional waveguide coupled to two giant atoms. By adjusting the accumulated phase shifts between the coupling points, we are able to effectively manipulate the…

Quantum Physics · Physics 2024-03-01 Wenju Gu , Lei Chen , Zhen Yi , Sujing Liu , Gao-xiang Li

Over the past decade, integrated quantum photonic technologies have shown great potential as a platform for studying quantum phenomena and realizing large-scale quantum information processing. Recently, there have been proposals for…

Narrow line-widths and the possibility of enhanced spontaneous emission via coupling to microcavities make semiconductor quantum dots ideal for harnessing coherent quantum phenomena at the single photon level. So far, however, all…

Mesoscale and Nanoscale Physics · Physics 2007-07-26 A. Muller , E. B. Flagg , P. Bianucci , D. G. Deppe , W. Ma , J. Zhang , G. J. Salamo , C. K. Shih

Quantum feedback is assuming increasingly important role in quantum control and quantum information processing. In this work we analyze the application of such feedback techniques in eliminating decoherence in open quantum systems. In order…

Quantum Physics · Physics 2016-11-15 Narayan Ganesan , Tzyh Jong Tarn