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In this work, we study the tradeoffs between the error probabilities of classical-quantum channels and the blocklength $n$ when the transmission rates approach the channel capacity at a rate slower than $1/\sqrt{n}$, a research topic known…

Quantum Physics · Physics 2017-05-26 Hao-Chung Cheng , Min-Hsiu Hsieh

We present an alternative framework for quantifying the coherence of quantum channels, which contains three conditions: the faithfulness, nonincreasing under sets of all the incoherent superchannels and the additivity. Based on the…

Quantum Physics · Physics 2022-04-20 Shi-Yun Kong , Ya-Juan Wu , Qiao-Qiao Lv , Zhi-Xi Wang , Shao-Ming Fei

It is proved that the energy-constrained Bures distance between arbitrary infinite-dimensional quantum channels is equal to the operator E-norm distance from any given Stinespring isometry of one channel to the set of all Stinespring…

Quantum Physics · Physics 2024-06-19 M. E. Shirokov

We study two complementary diagnostics of bipartite quantum channels, namely fidelity preservation across different classes of input states and entanglement generation from product inputs, given by properly defined entangling power for…

Quantum Physics · Physics 2026-05-27 Marcin Rudziński , Gianluigi Tartaglione , Karol Życzkowski

We analyze uncertainty relations on finite dimensional Hilbert spaces expressed in terms of classical fidelity, which are stronger then metric uncertainty relations introduced by Fawzi, Hayden and Sen. We establish validity of fidelity…

Quantum Physics · Physics 2017-03-08 Radosław Adamczak

A quantum ensemble $\{(p_x, \rho_x)\}$ is a set of quantum states each occurring randomly with a given probability. Quantum ensembles are necessary to describe situations with incomplete a priori information, such as the output of a…

Quantum Physics · Physics 2009-03-30 Ognyan Oreshkov , John Calsamiglia

We develop an approximation approach to infinite dimensional quantum channels based on detailed investigation of the continuity properties of entropic characteristics of quantum channels and operations (trace-nonincreasing completely…

Quantum Physics · Physics 2008-12-17 M. E. Shirokov , A. S. Holevo

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

In this work, we introduce a comprehensive statistical framework for assessing single-qubit quantum teleportation performance beyond the conventional average-fidelity benchmark. At first, we derive a closed-form expression for the full…

Quantum Physics · Physics 2025-10-16 D. G. Bussandri , G. M. Bosyk , P. Crespo Del Amo , K. Życzkowski

We provide a bound for the trace distance between two quantum states. The lower bound is based on the superfidelity, which provides the upper bound on quantum fidelity. One of the advantages of the presented bound is that it can be…

Quantum Physics · Physics 2009-02-11 Zbigniew Puchała , Jarosław Adam Miszczak

One of the key issues in quantum information theory related problems concerns with that of distinguishability of quantum states. In this context, Bures distance serves as one of the foremost choices among various distance measures. It also…

Quantum Physics · Physics 2023-03-29 Aritra Laha , Santosh Kumar

Most general dynamics of an open quantum system is commonly represented by a quantum channel, which is a completely positive trace-preserving map (CPTP or Kraus map). Well-known are the representations of quantum channels by Choi matrices…

Quantum Physics · Physics 2025-06-10 Ivan Russkikh , Boris Volkov , Alexander Pechen

Two channels are equivalent if their maximum likelihood (ML) decoders coincide for every code. We show that this equivalence relation partitions the space of channels into a generalized hyperplane arrangement. With this, we define a coding…

Information Theory · Computer Science 2018-02-07 Rafael G. L. D'Oliveira , Marcelo Firer

Given a quantum channel and a state which satisfy a fixed point equation approximately (say, up to an error $\varepsilon$), can one find a new channel and a state, which are respectively close to the original ones, such that they satisfy an…

Quantum Physics · Physics 2024-05-03 Robert Salzmann , Bjarne Bergh , Nilanjana Datta

We study the problem of measuring errors in non-trace-preserving quantum operations, with a focus on their impact on quantum computing. We propose an error metric that efficiently provides an upper bound on the trace distance between the…

Quantum Physics · Physics 2023-10-10 Yu Shi , Edo Waks

An analogue of the quadratic Wasserstein (or Monge-Kantorovich) distance between Borel probability measures on $\mathbf{R}^d$ has been defined in [F. Golse, C. Mouhot, T. Paul: Commun. Math. Phys. 343 (2015), 165-205] for density operators…

Mathematical Physics · Physics 2021-02-10 Emanuele Caglioti , François Golse , Thierry Paul

We propose and investigate bounds on quantum process fidelity of quantum filters, i.e. probabilistic quantum operations represented by a single Kraus operator K. These bounds generalize the Hofmann bounds on quantum process fidelity of…

Quantum Physics · Physics 2016-08-08 Michal Sedlak , Jaromír Fiurášek

In this paper we present an optimal protocol by which an unknown state on a Hilbert space of dimension $N$ can be approximately stored in an $M$-dimensional quantum system or be approximately teleported via an $M$-dimensional quantum…

Quantum Physics · Physics 2009-11-07 Thomas Laustsen , Klaus Molmer

Quantum teleportation should surpass maximum fidelity thresholds possible with local measurements and classical communications. Benchmarks have been established when states are drawn from a uniform distribution of qubits or coherent states…

Quantum Physics · Physics 2026-05-26 Tomáš Opatrný , Allison Brattley , Kunal K. Das

Quantum channel, as the information transmitter, is an indispensable tool in quantum information theory. In this paper, we study a class of special quantum channels named the mixed-permutation channels. The properties of these channels are…

Quantum Physics · Physics 2024-01-15 Lin Zhang , Ming-Jing Zhao