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It is shown that phase-insensitive Gaussian bosonic channels are majorization-preserving over the set of passive states of the harmonic oscillator. This means that comparable passive states under majorization are transformed into equally…

Quantum Physics · Physics 2016-07-28 Michael G. Jabbour , Raúl García-Patrón , Nicolas J. Cerf

A general quantum noisy channel is analyzed, wherein the transmitted qubits may experience symmetry-breaking decoherence, along with memory effects. We find the optimal basis not to be fully entangled, but a combination of factorized and…

Quantum Physics · Physics 2015-05-13 Goren Gordon , Gershon Kurizki

The operational capacity of Gaussian MIMO channels with memory was obtained by Brandenburg and Wyner in [9] under certain mild assumptions on the channel impulse response and its noise covariance matrix, which essentuially require channel…

Information Theory · Computer Science 2022-05-11 Sergey Loyka , Charalambos D. Charalambous

We study the LOCC-assisted quantum capacity of bosonic dephasing channel with energy constraint on input states. We start our analysis by focusing on the energy-constrained squashed entanglement of the channel, which is an upper bound for…

Quantum Physics · Physics 2023-10-20 Amir Arqand , Laleh Memarzadeh , Stefano Mancini

Subtle quantum properties offer exciting new prospects in optical communications. Quantum entanglement enables the secure exchange of cryptographic keys and the distribution of quantum information by teleportation. Entangled bright beams of…

The method of complementary channel for analysis of reversibility (sufficiency) of a quantum channel with respect to families of input states (pure states for the most part) are considered and applied to Bosonic linear (quasi-free)…

Quantum Physics · Physics 2013-11-12 M. E. Shirokov

We show how adaptive protocols of quantum and private communication through bosonic Gaussian channels can be simplified into much easier block versions that involve resource states with finite energy. This is achieved by combining the…

Quantum Physics · Physics 2018-10-17 Riccardo Laurenza , Samuel L. Braunstein , Stefano Pirandola

We survey the state of the art for the proof of the quantum Gaussian optimizer conjectures of quantum information theory. These fundamental conjectures state that quantum Gaussian input states are the solution to several optimization…

Mathematical Physics · Physics 2018-08-31 Giacomo De Palma , Dario Trevisan , Vittorio Giovannetti , Luigi Ambrosio

Compound channel models offer a simple and straightforward way of analyzing the stability of decoder design under model variations. With this work we provide a coding theorem for a large class of practically relevant compound channel…

Information Theory · Computer Science 2021-05-11 Andrea Cacioppo , Janis Nötzel , Matteo Rosati

The sum-rate capacity of the parallel Gaussian interference channel is shown to be achieved by independent transmission across sub-channels and treating interference as noise in each sub-channel if the channel coefficients and power…

Information Theory · Computer Science 2009-03-04 Xiaohu Shang , Biao Chen , Gerhard Kramer , H. Vincent Poor

Quantum superchannels are maps whose input and output are quantum channels. Rather than taking the domain to be the space of all linear maps we motivate and define superchannels on the operator system spanned by quantum channels. Extension…

Quantum Physics · Physics 2022-10-04 Pádraig Daly

Combining two entanglement-breaking channels into a correlated-noise environment restores the distribution of entanglement. Surprisingly, this reactivation can be induced by the injection of separable correlations from the composite…

Quantum Physics · Physics 2014-02-11 Stefano Pirandola

Quantum steering is a crucial quantum resource that lies intermediate between entanglement and Bell nonlocality. Gaussian channels, meanwhile, play a foundational role in diverse quantum protocols, secure communication, and related fields.…

Quantum Physics · Physics 2026-04-13 Ruifen Ma , Yanjing Sun , Xiaofei Qi

We analyze qubit channels by exploiting the possibility of representing two-level quantum systems in terms of characteristic functions. To do so, we use functions of non-commuting variables (Grassmann variables), defined in terms of…

Quantum Physics · Physics 2008-09-12 Filippo Caruso , Vittorio Giovannetti

Superadditivity effects in the classical capacity of discrete multi-access channels (MACs) and continuous variable (CV) Gaussian MACs are analysed. New examples of the manifestation of superadditivity in the discrete case are provided…

Quantum Physics · Physics 2012-03-14 L. Czekaj , J. K. Korbicz , R. W. Chhajlany , P. Horodecki

Entanglement properties of Gaussian states of light as well as the security of continuous variable quantum key distribution with Gaussian states in free-space fading channels are studied. These qualities are shown to be sensitive to the…

A fully general strong converse for channel coding states that when the rate of sending classical information exceeds the capacity of a quantum channel, the probability of correctly decoding goes to zero exponentially in the number of…

Quantum Physics · Physics 2013-05-29 Robert Koenig , Stephanie Wehner

We propose examples of low dimensional quantum channels demonstrating different forms of superactivation of one-shot zero-error capacities, in particular, the extreme superactivation (this complements the recent result of T.S.Cubitt and…

Quantum Physics · Physics 2015-03-19 Maksim Shirokov , Tatiana Shulman

Estimating the information transmission capability of a quantum channel remains one of the fundamental problems in quantum information processing. In contrast to classical channels, the information-carrying capability of quantum channels is…

Quantum Physics · Physics 2024-07-26 Aditya Nema , Ananda G. Maity , Sergii Strelchuk , David Elkouss

We prove the longstanding conjecture stating that Gaussian thermal input states minimize the output von Neumann entropy of one-mode phase-covariant quantum Gaussian channels among all the input states with a given entropy. Phase-covariant…

Quantum Physics · Physics 2017-04-26 Giacomo De Palma , Dario Trevisan , Vittorio Giovannetti