Quantum noise is ubiquitous to quantum systems as they incessantly interact with their surroundings and results in degrading useful resources such as coherence for single quantum systems and quantum correlations for multipartite systems. Given the importance of these resources in various quantum information processing protocols, it is of the utmost importance to characterize how deteriorating a particular noise scenario (quantum channel) is in reference to a certain resource. Here we develop a theory of coherence-breaking channels for single quantum systems. Any quantum channel on a single quantum system will be called a coherence-breaking channel if it is an incoherent channel and maps any state to an incoherent state. We explicitly and exhaustively characterize these coherence-breaking channels. Moreover, we define the coherence-breaking indices for incoherent quantum channels and present various examples to elucidate this concept. We further introduce the concept of coherence sudden death under noisy evolutions and make an explicit connection of the phenomenon of coherence sudden death with the coherence-breaking channels and the coherence-breaking indices together with various suggestive examples. Furthermore, for higher-dimensional Hilbert spaces, we establish the typicality of the dynamics of coherence under any incoherent quantum channel exploiting the concentration of measure phenomenon.
Quantum noise is ubiquitous to quantum systems as they incessantly interact with their surroundings and results in degrading useful resources such as coherence for single quantum systems and quantum correlations for multipartite systems. Given the importance of these resources in various quantum information processing protocols, it is of the utmost importance to characterize how deteriorating a particular noise scenario (quantum channel) is in reference to a certain resource. Here we develop a theory of coherence-breaking channels for single quantum systems. Any quantum channel on a single quantum system will be called a coherence-breaking channel if it is an incoherent channel and maps any state to an incoherent state. We explicitly and exhaustively characterize these coherence-breaking channels. Moreover, we define the coherence-breaking indices for incoherent quantum channels and present various examples to elucidate this concept. We further introduce the concept of coherence sudden death under noisy evolutions and make an explicit connection of the phenomenon of coherence sudden death with the coherence-breaking channels and the coherence-breaking indices together with various suggestive examples. Furthermore, for higher-dimensional Hilbert spaces, we establish the typicality of the dynamics of coherence under any incoherent quantum channel exploiting the concentration of measure phenomenon.
The interaction of quantum system and its environment brings out abundant quantum phenomenons. The sudden death of quantum resources, including entanglement, quantum discord and coherence, have been studied from the perspective of quantum breaking channels (QBC). QBC of quantum resources reveal the common features of quantum resources. The definition of QBC implies the relationship between quantum resources. However, sudden death of quantum resources can also appear under some other quantum channels. We consider the dynamics of Bell-diagonal states under a stochastic dephasing noise along the z-direction, and the sudden death and sudden birth of quantum discord are investigated. Next we explain this phenomenon from the geometric structure of quantum discord. According to the above results, the states with sudden death and sudden birth can be filtered in three-parameter space. Then we provide two necessary conditions to judge which kind of noise channels can make Bell-diagonal states sudden death and sudden birth. Moreover, the relation between quantum discord and coherence indicates that the sudden death and sudden birth of quantum discord implies the sudden death and sudden birth of coherence in an optimal basis.
Manipulating dynamical evolution is an important task in quantum information. The sudden death phenomenon (SDP), which is predicted to be unattainable beyond entanglement [T. Yu and J. H. Eberly, Sudden death of entanglement, Science 323, 598 (2009)], would be an especially surprising feature in quantum coherence. In this paper, we modulate the spatial modes of photons and build a spatially inclined channel using a series of specially made quartz plate pairs. Within this channel, sudden changes in coherence occur in open-quantum systems. We, then, describe the SDP within a general theoretical framework of sudden quantum-coherence changes and by defining the nth-order sudden coherence change. Moreover, by adding non-Markovian noise, we find that coherence can rebirth after a sudden death. We further compare the sudden change features in coherence and quantum entanglement. We find that both coherence and entanglement perform identical dynamical processes upon Bell diagonal states, although their dynamical characteristics change when the initial state is partially entangled. Our results provide insights into the sudden change phenomena of quantum correlations beyond entanglement along with intriguing perspectives on quantum coherence dynamics.
The occurrence of entanglement sudden death in the evolution of a bipartite system depends on both the initial state and the channel responsible for the evolution. An extreme case is that of entanglement-breaking channels, which are channels that, acting on only one of the subsystems, drives them to full disentanglement, regardless of the initial state. In general, one can find certain combinations of initial states and channels acting on one or both subsystems that can result in entanglement sudden death or not. Neither the channel nor the initial state are responsible for this effect but their combination. In this paper we show that, for two entangled qubits, when entanglement sudden death occurs, the evolution can be mapped to that of an effective entanglement-breaking channel on a modified initial state. Our results allow to anticipate which states will suffer entanglement sudden death or not for a given evolution. An experiment with polarization-entangled photons demonstrates the utility of this result in a variety of cases.
Quantum coherence is not only a fundamental concept of quantum mechanics, but also an important physical resource for quantum information processing. Along with the formulation of the resource theoretic framework of quantum coherence, the quantification of coherence is still one of the recent research focuses. Quantum coherence is also very fragile, and the environmental noise usually induces a system to decohere. Hence it is also an important subject to make clear the dynamical behavior and to seek a flexible way of preserving quantum coherence of an open quantum system. Besides, there are many potential applications of quantum coherence in quantum many-body system, quantum thermodynamics, quantum biology and other related fields. We review in this paper the resource theoretic framework for quantifying coherence and the relevant quantum coherence measures defined within this framework which includes the relative entropy of coherence, the l1 norm of coherence, the entanglement-based measure of coherence, the convex roof measure of coherence, and the robustness of coherence. We also review the dynamical behaviors of quantum coherence for certain open quantum systems, the coherence generating and breaking power of typical quantum channels, and the freezing phenomenon of quantum coherence. Moreover, we exemplify applications of quantum coherence in Deutsch-Jozsa algorithm, Grover search algorithms, and the study of quantum phase transitions in multipartite systems. We hope that these results may provide not only an overview of the relevant field, but also an outlook of the future research direction of this exciting field.
Quantum resources — coherence, entanglement, nonlocality, and information precision — are not static properties. They are dynamically interconvertible, and their fates under noise channels define the practical boundaries of quantum advantage. This paper synthesizes six recent preprints from the quant-ph and cond-mat.stat-mech arXiv corpus to develop a candidate heuristic framework (not a unified derivation) for understanding how noise-channel geometry governs the conversion, degradation, and preservation of quantum resources across distinct physical platforms. The central thesis, stated as a structural pattern worth investigating rather than a proven theorem, is: **the qualitative behavior of quantum resource dynamics under noise — whether degradation is monotonic, sudden-death-exhibiting, or dimension-dependent — is determined primarily by the geometric structure of the noise channel, not by the magnitude of the resource being converted.** This pattern appears independently across coherence-to-entanglement transduction in qubits [corpus:arxiv:2606.16916], high-dimensional qudit systems [corpus:arxiv:2606.16695], bath-memory-mediated transport precision [corpus:arxiv:2606.17026], entanglement fragility in W-class states [corpus:arxiv:2606.12307], quantum scrambling in scarred billiards [corpus:arxiv:2606.16865], and non-Hermitian grid-state deformation [corpus:arxiv:2606.17036]. The falsification path for the central thesis is concrete: if a systematic survey of noise channels finds that sudden-death thresholds and monotonicity classes are not predictable from channel geometry alone — specifically, if amplitude-damping and phase-damping channels produce qualitatively identical degradation signatures for the same input resource magnitude — the geometric-structure thesis fails. The paper identifies this as a computable test using existing density-matrix simulation tools. Sources span quant-ph (primary, five papers) and cond-mat.stat-mech (one paper, weakly connected via precision transport). The abstract-only reading constraint is acknowledged throughout. --- Authorship: Saluca Agentic AI Research Team (Saluca LLC). AI-drafted from arXiv preprint corpus on the date in the filename. Cited arXiv preprints: 2606.12307, 2606.12700, 2606.16695, 2606.16712, 2606.16865, 2606.16916, 2606.16948, 2606.17026, 2606.17036
A typical bipartite quantum protocol, such as EPR-steering, relies on two quantum features, entanglement of states and incompatibility of measurements. Noise can delete both of these quantum features. In this work we study the behavior of incompatibility under noisy quantum channels. The starting point for our investigation is the observation that compatible measurements cannot become incompatible by the action of any channel. We focus our attention to channels which completely destroy the incompatibility of various relevant sets of measurements. We call such channels incompatibility breaking , in analogy to the concept of entanglement breaking channels. This notion is relevant especially for the understanding of noise-robustness of the local measurement resources for steering.