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The problem of quantum harmonic oscillator with "regular+random" square frequency, subjected to "regular+random external force, is considered in framework of representation of the wave function by complex-valued random process. Average…

Quantum Physics · Physics 2007-05-23 A. S. Gevorkyan , A. A. Udalov

Quantitative analysis of discontinuity of basic characteristics of quantum states and channels is presented. First we consider general estimates for discontinuity jump (loss) of the von Neumann entropy for a given converging sequence of…

Quantum Physics · Physics 2021-09-28 M. E. Shirokov

Quantum metrology offers an enhanced performance in experiments such as gravitational wave-detection, magnetometry or atomic clocks frequency calibration. The enhancement, however, requires a delicate tuning of relevant quantum features…

Quantum Physics · Physics 2013-07-25 Jan Kolodynski , Rafal Demkowicz-Dobrzanski

In this work, we study two different approaches to defining the entropy of a quantum channel. One of these is based on the von Neumann entropy of the corresponding Choi-Jamio{\l}kowski state. The second one is based on the relative entropy…

Quantum Physics · Physics 2021-08-17 Dariusz Kurzyk , Łukasz Pawela , Zbigniew Puchała

The traditional framework of quantum metrology commonly assumes unlimited access to resources, overlooking resource constraints in realistic scenarios. As such, the optimal strategies therein can be infeasible in practice. Here, we…

Quantum Physics · Physics 2026-02-25 Longyun Chen , Yuxiang Yang

Regarding the strange properties of quantum entropy and entanglement, e.g., the negative quantum conditional entropy, we revisited the foundations of quantum entropy, namely, von Neumann entropy, and raised the new method of quantum…

Quantum Physics · Physics 2012-05-08 Dong-Sheng Wang

The de Finetti representation theorem for continuous variable quantum system is first developed to approximate an N-partite continuous variable quantum state with a convex combination of independent and identical subsystems, which requires…

Quantum Physics · Physics 2016-09-28 Murphy Yuezhen Niu

Extending hyperuniformity from classical to quantum fluctuations in electron systems yields a framework that identifies quantum phase transitions and reveals underlying gap structures through the quantum weight. We study long-wavelength…

Strongly Correlated Electrons · Physics 2026-01-27 Junmo Jeon , Shiro Sakai

We describe analytical properties of the average output entropy of a quantum channel as a function of a pair (channel, input ensemble). In particular, tight semicontinuity bounds for this function with the rank/energy constraints are…

Quantum Physics · Physics 2024-04-12 M. E. Shirokov

In these notes we will give an overview and road map for a definition and characterization of (relative) entropy for both classical and quantum systems. In other words, we will provide a consistent treatment of entropy which can be applied…

Mathematical Physics · Physics 2025-05-02 W. A. Majewski , L. E. Labuschagne

We propose a unified method for the large space-time scaling limit of \emph{linear} collisional kinetic equations in the whole space. The limit is of \emph{fractional} diffusion type for heavy tail equilibria with slow enough decay, and of…

Analysis of PDEs · Mathematics 2023-02-22 Emeric Bouin , Clément Mouhot

We consider a class (convex set) of quantum states containing all finite rank states and infinite rank states with the sufficient rate of decreasing of eigenvalues (in particular, all Gaussian states). Quantum states from this class are…

Quantum Physics · Physics 2021-09-28 M. E. Shirokov

We consider universal methods for obtaining (uniform) continuity bounds for characteristics of multipartite quantum systems. We pay a special attention to infinite-dimensional multipartite quantum systems under the energy constraints. By…

Quantum Physics · Physics 2021-09-28 M. E. Shirokov

We pose and solve the problem of quantum filtering based on continuous-in-time quadrature measurements (homodyning) for the case where the quantum process is in a thermal state. The standard construction of quantum filters involves the…

Quantum Physics · Physics 2026-01-13 John Gough

This paper establishes a general theory of energy-constrained quantum and private capacities of quantum channels. We begin by defining various energy-constrained communication tasks, including quantum communication with a uniform energy…

Quantum Physics · Physics 2018-11-22 Mark M. Wilde , Haoyu Qi

We review in a unified way a recently proposed method to detect properties of unknown quantum channels and lower bounds to quantum capacities, without resorting to full quantum process tomography. The method is based on the preparation of a…

Quantum Physics · Physics 2017-12-19 Chiara Macchiavello , Massimiliano F. Sacchi

We review recent developments in the theory of quantum dynamics in ultra-cold atomic physics, including exact techniques, but focusing on methods based on phase-space mappings that are appli- cable when the complexity becomes exponentially…

Environmental interactions are ubiquitous in any real-world application of a quantum information processing protocol. Such interactions result in depletion of quantum resources. Two important figure of merits in the context of quantum…

Quantum Physics · Physics 2024-06-06 Tapaswini Patro , Kaushiki Mukherjee , Nirman Ganguly

We show that Frenkel's integral representation of the quantum relative entropy provides a natural framework to derive continuity bounds for quantum information measures. Our main general result is a dimension-independent semi-continuity…

Quantum Physics · Physics 2025-03-04 Mario Berta , Ludovico Lami , Marco Tomamichel

Macroscopic quantum tunneling is described using the master equation for the reduced Wigner function of an open quantum system at zero temperature. Our model consists of a particle trapped in a cubic potential interacting with an…

Quantum Physics · Physics 2011-08-04 Esteban Calzetta , Enric Verdaguer