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We determine both the quantum and the private capacities of low-noise quantum channels to leading orders in the channel's distance to the perfect channel. It has been an open problem for more than 20 years to determine the capacities of…

Quantum Physics · Physics 2023-12-06 Felix Leditzky , Debbie Leung , Graeme Smith

This paper presents the first proof of polarization for the deletion channel with a constant deletion rate and a regular hidden-Markov input distribution. A key part of this work involves representing the deletion channel using a trellis…

Information Theory · Computer Science 2020-07-24 Ido Tal , Henry D. Pfister , Arman Fazeli , Alexander Vardy

The 3GPP suggests to combine dual polarized (DP) antenna arrays with the double directional (DD) channel model for downlink channel estimation. This combination strikes a good balance between high-capacity communications and parsimonious…

Signal Processing · Electrical Eng. & Systems 2018-10-29 Cheng Qian , Xiao Fu , Nicholas D. Sidiropoulos , Ye Yang

For information transmission a discrete time channel with independent additive Gaussian noise is used. There is also feedback channel with independent additive Gaussian noise, and the transmitter observes without delay all outputs of the…

Information Theory · Computer Science 2012-08-15 M. V. Burnashev , H. Yamamoto

Two quantum channels are called compatible if they can be obtained as marginals from a single broadcasting channel; otherwise they are incompatible. We derive a characterization of the compatibility relation in terms of concatenation and…

Quantum Physics · Physics 2017-03-06 Teiko Heinosaari , Takayuki Miyadera

A modular method was suggested before to recover a band limited signal from the sample and hold and linearly interpolated (or, in general, an nth-order-hold) version of the regular samples. In this paper a novel approach for compensating…

Computer Vision and Pattern Recognition · Computer Science 2012-05-15 Mohammad Tofighi , Ali Ayremlou , Farokh Marvasti

Two approaches used in the description of the channeling radiation emitted from relativistic positrons are compared with each other. In the first (traditional) case, the probability of the process is proportional to a sum of absolute…

Quantum Physics · Physics 2007-05-23 V. F. Boldyshev , M. G. Shatnev

We extend the definition of the conditional min-entropy from bipartite quantum states to bipartite quantum channels. We show that many of the properties of the conditional min-entropy carry over to the extended version, including an…

Quantum Physics · Physics 2019-04-04 Gilad Gour

This is an addendum to our previous work cond-mat/9705048 (published in Europhysics Letters 41, 213 (1998)), clarifying the construction of the two-particle scattering matrices used for studying the magnetic impurity behavior in a…

Strongly Correlated Electrons · Physics 2009-10-31 A. A. Zvyagin , H. Johannesson , M. Granath

The ability to characterise and discern quantum channels is a crucial aspect of noisy quantum technologies. In this work, we explore the problem of distinguishing quantum channels when limited to sub-exponential resources, framed as von…

Quantum Physics · Physics 2025-07-18 Timothy Heightman , Grzegorz Rajchel-Mieldzioć

Quantum channel capacities give the fundamental performance limits for information flow over a communication channel. However, the prevalence of superadditivity is a major obstacle to understanding capacities, both quantitatively and…

Quantum Physics · Physics 2025-09-10 Graeme Smith , Peixue Wu

Recently, a purely quantum version of polar codes has been proposed in [1] based on a quantum channel combining and splitting procedure, where a randomly chosen two-qubit Clifford unitary acts as channel combining operation. Here, we…

Quantum Physics · Physics 2025-03-12 Ashutosh Goswami , Mehdi Mhalla , Valentin Savin

This work considers communication networks where individual links can be described as MIMO channels. Unlike orthogonal modulation methods (such as the singular-value decomposition), we allow interference between sub-channels, which can be…

Information Theory · Computer Science 2016-11-17 Anatoly Khina , Yuval Kochman , Uri Erez

We provide efficient and intuitive tools for deriving bounds on achievable precision in quantum enhanced metrology based on the geometry of quantum channels and semi-definite programming. We show that when decoherence is taken into account,…

Quantum Physics · Physics 2012-09-19 Rafal Demkowicz-Dobrzanski , Jan Kolodynski , Madalin Guta

The problem of dephasing channel discrimination is addressed for finite-dimensional systems. In particular, the optimization with respect to input states without energy constraint is solved analytically for qubit, qutrit and ququart.…

Quantum Physics · Physics 2023-10-25 Milajiguli Rexiti , Laleh Memarzadeh , Stefano Mancini

Quantum process tomography, the standard procedure to characterize any quantum channel in nature, is affected by a circular argument: in order to characterize the channel, the tomographic preparation and measurement need in turn to be…

Quantum Physics · Physics 2016-06-13 Michele Dall'Arno , Sarah Brandsen , Francesco Buscemi

In this paper, we address the problem of designing a quantum encoder that maximizes the minimum output purity of a given decohering channel, where the minimum is taken over all possible pure inputs. This problem is cast as a max-min…

Quantum Physics · Physics 2011-11-09 Naoki Yamamoto , Maryam Fazel

The deletion channel is the simplest point-to-point communication channel that models lack of synchronization. Despite significant effort, little is known about its capacity, and even less about optimal coding schemes. In this paper we…

Information Theory · Computer Science 2011-05-02 Yashodhan Kanoria , Andrea Montanari

Quantum correlation can be created by a local operation from some initially classical states. We prove that the necessary and sufficient condition for a local trace-preserving channel to create quantum correlation is that it is not a…

Quantum Physics · Physics 2012-03-08 Xueyuan Hu , Heng Fan , D. L. Zhou , Wu-Ming Liu

Decoupling multivariate polynomials is useful for obtaining an insight into the workings of a nonlinear mapping, performing parameter reduction, or approximating nonlinear functions. Several different tensor-based approaches have been…

Numerical Analysis · Mathematics 2019-01-31 Konstantin Usevich , Philippe Dreesen , Mariya Ishteva