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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

We consider fault-tolerant quantum computation in the context where there are no fresh ancilla qubits available during the computation, and where the noise is due to a general quantum channel. We show that there are three classes of noisy…

Quantum Physics · Physics 2013-01-11 Michael Ben-Or , Daniel Gottesman , Avinatan Hassidim

We formulate the notion of quantum channels in the framework of quantum tomography and address there the issue of whether such maps can be regarded as classical stochastic maps. In particular kernels of maps acting on probability…

Quantum Physics · Physics 2018-06-06 G. G. Amosov , S. Mancini , V. I. Man'ko

For a quantum channel with additive Gaussian quantum noise, at the large input energy side, we prove that the one shot capacity is achieved by the thermal noise state for all Gaussian state inputs, it is also true for non-Gaussian input in…

Quantum Physics · Physics 2015-05-13 Xiao-yu Chen

Information transmission over channels with transceiver distortion is investigated via generalized mutual information (GMI) under Gaussian input distribution and nearest-neighbor decoding. A canonical transceiver structure in which the…

Information Theory · Computer Science 2016-02-11 Wenyi Zhang

Decoherence of quantum systems is described by quantum channels. However, a complete understanding of such channels, especially in the multi-particle setting, is still an ongoing difficult task. We propose the family of quantum maps that…

We introduce a new set of quantum channels: resonant multilevel amplitude damping (ReMAD) channels. Among other instances, they can describe energy dissipation effects in multilevel atomic systems induced by the interaction with a…

Quantum Physics · Physics 2023-01-25 Stefano Chessa , Vittorio Giovannetti

Thermal attenuator channels model the decoherence of quantum systems interacting with a thermal bath, e.g., a two-level system subject to thermal noise and an electromagnetic signal travelling through a fiber or in free-space. Hence…

Quantum Physics · Physics 2018-12-12 Matteo Rosati , Andrea Mari , Vittorio Giovannetti

The task of jointly communicating a message and reconstructing a common estimate of the channel state is examined for a fading Gaussian model with additive state interference. The state is an independent and identically distributed Gaussian…

Information Theory · Computer Science 2026-01-07 Viswanathan Ramachandran

The quantum capacity of a quantum channel captures its capability for noiseless quantum communication. It lies at the heart of quantum information theory. Unfortunately, our poor understanding of nonadditivity of coherent information makes…

Quantum Physics · Physics 2018-12-07 Felix Leditzky , Debbie Leung , Graeme Smith

The capacity of peak-power limited, single-antenna, non-coherent, flat-fading channels with memory is considered. The emphasis is on the capacity pre-log, i.e., on the limiting ratio of channel capacity to the logarithm of the…

Information Theory · Computer Science 2008-04-14 Tobias Koch , Amos Lapidoth

Recently it was shown that the main distinguishing features of quantum mechanics (QM) can be reproduced by a model based on classical random fields, so called prequantum classical statistical field theory (PCSFT). This model provides a…

Quantum Physics · Physics 2012-10-17 Andrei Khrennikov , Masanori Ohya , Naboru Watanabe

Quantum coherence is a fundamental aspect of quantum physics and plays a central role in quantum information science. This essential property of the quantum states could be fragile under the influence of the quantum operations. The extent…

Quantum Physics · Physics 2018-10-18 Fereshte Shahbeigi , Seyed Javad Akhtarshenas

The study of quantum channels is the fundamental field and promises wide range of applications, because any physical process can be represented as a quantum channel transforming an initial state into a final state. Inspired by the method…

Quantum Physics · Physics 2017-06-27 Shi-Jie Wei , Tao Xin , Gui-Lu Long

We investigate the possibility of dividing quantum channels into concatenations of other channels, thereby studying the semigroup structure of the set of completely-positive trace-preserving maps. We show the existence of 'indivisible'…

Mathematical Physics · Physics 2015-06-26 Michael M. Wolf , J. Ignacio Cirac

Upper bounds on the capacity of vector Gaussian channels affected by fading are derived under peak amplitude constraints at the input. The focus is on constraint regions that can be decomposed in a Cartesian product of sub-regions. This…

Information Theory · Computer Science 2022-07-05 Antonino Favano , Marco Ferrari , Maurizio Magarini , Luca Barletta

We study the deviations from the exponential decay law, both in quantum field theory (QFT) and quantum mechanics (QM), for an unstable particle which can decay in (at least) two decay channels. After a review of general properties of…

Nuclear Theory · Physics 2015-05-30 Francesco Giacosa

A formula is derived for the capacity of the Gaussian channel with a benevolent message-cognizant rate-limited helper that provides a noncausal description of the noise to the encoder and decoder. This capacity is strictly larger than when…

Information Theory · Computer Science 2023-10-25 Amos Lapidoth , Ligong Wang , Yiming Yan

In this article, we are proposing a closed-form solution for the capacity of the single quantum channel. The Gaussian distributed input has been considered for the analytical calculation of the capacity. In our previous couple of papers, we…

Information Theory · Computer Science 2023-02-17 Mouli Chakraborty , Harun Siljak , Indrakshi Dey , Nicola Marchetti

This paper studies network information theory problems where the external noise is Gaussian distributed. In particular, the Gaussian broadcast channel with coherent fading and the Gaussian interference channel are investigated. It is shown…

Information Theory · Computer Science 2010-02-12 Emmanuel Abbe , Lizhong Zheng