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We investigate the coherence of quantum channels and establish a resource theory for quantifying the coherence of quantum channels via Choi matrix. To this aim, we define the incoherent channels and incoherent superchannels. This theory…

Quantum Physics · Physics 2019-11-12 Jianwei Xu

Quantum phase estimation is a core task in quantum technologies ranging from metrology to quantum computing, where it appears as a key subroutine in various algorithms. Here, we quantitatively connect the performance of phase estimation…

Quantum Physics · Physics 2026-05-11 Felix Ahnefeld , Thomas Theurer , Martin B. Plenio

The concept of quantum coherence, including various ways to quantify the degree of coherence with respect to the prescribed basis, is currently the subject of active research. The complementarity of quantum coherence in different bases was…

Quantum Physics · Physics 2017-09-08 Alexey E. Rastegin

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

We study mixed unitary quantum channels generated by irreducible projective unitary representations of finite groups. Under some assumptions on the probability distribution determining a mixture the classical capacity of the channel is…

Quantum Physics · Physics 2022-05-26 Grigori Amosov

Quantifying quantum coherence is a key task in the resource theory of coherence. Here we establish a good coherence monotone in terms of a state conversion process, which automatically endows the coherence monotone with an operational…

Quantum Physics · Physics 2020-07-01 Deng-hui Yu , Li-qiang Zhang , Chang-shui Yu

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

Various measures have been suggested recently for quantifying the coherence of a quantum state with respect to a given basis. We first use two of these, the l_1-norm and relative entropy measures, to investigate tradeoffs between the…

Quantum Physics · Physics 2015-10-08 Shuming Cheng , Michael J. W. Hall

The emerging quantum technologies rely on our ability to establish and control quantum systems in nonclassical states, exhibiting entanglement and quantum coherence. It is thus crucial to understand how entanglement and coherence can be…

Quantum Physics · Physics 2022-06-22 Masaya Takahashi , Swapan Rana , Alexander Streltsov

Local noise can produce quantum correlations on an initially classically correlated state, provided that it is not represented by a unital or semi-classical channel \cite{DagmarBruss}. We find the power of any given local channel for…

Quantum Physics · Physics 2015-06-12 Tahere Abad , Vahid Karimipour , Laleh Memarzadeh

We propose a general method to operationally quantify the resourcefulness of quantum channels via channel discrimination, an important information processing task. A main result is that the maximum success probability of distinguishing a…

Quantum Physics · Physics 2020-03-04 Lu Li , Kaifeng Bu , Zi-Wen Liu

Quantum Gaussian channels play a key role in quantum information theory. In particular, the attenuation and amplification channels are useful to describe noise and decoherence effects on continuous variables systems. They are directly…

Quantum Physics · Physics 2021-03-22 Jonas F. G. Santos , C. H. S. Vieira

Quantum coherence as an asymmetry relative to a translation group generated by a Hermitian operator, is a necessary resource for the quantum parameter estimation. On the other hand, the sensitivity of the parameter estimation is known to be…

The relations between quantum coherence and quantum interference are discussed. A general method for generation of quantum coherence through interference-induced state selection is introduced and then applied to `simple' atomic systems…

Quantum Physics · Physics 2007-05-23 Jean Claude Garreau

We analyze the optimal basis for generating the maximum relative entropy of quantum coherence by an arbitrary gate on a two-qubit system. The optimal basis is not unique, and the high quantum coherence generating gates are also typically…

Quantum Physics · Physics 2023-03-14 Aparajita Bhattacharyya , Ahana Ghoshal , Ujjwal Sen

In this paper the random channels and their compositions in the space of quantum states are studied. For compositions of i.i.d. random unitary channels, the limit behaviour of probability distributions is described. The sufficient condition…

Quantum Physics · Physics 2026-03-27 E. A. Dzhenzher , S. V. Dzhenzher , V. Zh. Sakbaev

This paper studies the quantification and structural properties of quantum average correlation based on average coherence. Motivated by two mathematically equivalent approaches to define average coherence: one by averaging over complete…

Quantum Physics · Physics 2026-04-28 Xiaoyu Ma , Qing-Hua Zhang , Cong Xu

Unambiguous unitary maps and unambiguous unitary quantum channels are introduced and some of their properties are derived. These properties ensure certain simple form for the measurements involved in realizing an unambiguous unitary quantum…

Quantum Physics · Physics 2008-11-14 Shengjun Wu , Xuemei Chen

The conventional coherence is defined with respect to a fixed orthonormal basis, i.e., to a von Neumann measurement. Recently, generalized quantum coherence with respect to general positive operator-valued measurements (POVMs) has been…

Quantum Physics · Physics 2022-01-04 Jianwei Xu , Lin Zhang , Shao-Ming Fei

Based on the theory of quantum mechanics, intrinsic randomness in measurement distinguishes quantum effects from classical ones. From the perspective of states, this quantum feature can be summarized as coherence or superposition in a…

Quantum Physics · Physics 2017-04-03 Xiao Yuan , Hongyi Zhou , Zhu Cao , Xiongfeng Ma