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We discuss the notions of mutual information and conditional information for noncomposite systems, classical and quantum; both the mutual information and the conditional information are associated with the presence of hidden correlations in the state of a single qudit. We consider analogs of the entanglement phenomena in the systems without subsystems related to strong hidden quantum correlations., 12 pages

We discuss the relation between entropy and information from the physicists point of view differing between bound and free information. The quantitative physical aspects of information flow are given by flows of entropy, which are closely related to the reduction of uncertainty and the predictability of events. Free information is considered as a quantity, which has intrinsic non – physical components, and is originally created by selforganization and evolution. Bound and free information are both represented by a matter carrier but not as tight – bounded like mass or energy. Free information is connected with information – processing; it is introduced as a binary relation between a sender and a receiver, which may have different carriers, it is essentially characterized by symbolic representations. Processing free information is originally created by selforganization on the early earth and is connected with the origin of life, therefore it is always at least indirectly related to living systems.

The coherent information of quantum channels plays a important role in quantum information theory as it can be used to calculate the quantum capacity of a channel. However, it is a non-linear, non-differentiable optimization problem. This thesis discusses that by restricting to the space of positive definite density matrices and restricting the class of quantum channels to be strictly positive, the coherent information becomes differentiable. This allows the computation of the Riemannian gradient and Hessian of the coherent information. It will be shown that the maximally mixed state is a critical point for the $n$-shot coherent information of the Pauli, dephrasure and Pauli-erasure channels. In addition, the classification of the maximally mixed state as a local maxima/minima and saddle-point will be solved for the one shot coherent information. The hope of this work is to provide a new avenue to explore the quantum capacity problem.

Embodied intelligent agents that are equipped with sensors and actuators have unique characteristics and requirements regarding the storage, management, and usage of information. The goal is to perform intentional activities, within the perception-action loop of the agent, based on the information acquired from its senses, background knowledge, naive physics knowledge, etc. The challenge is to integrate many different types of information required for competent and intelligent decision-making into a coherent information system. In this chapter, we will describe a conceptual framework in which such information system can be represented and talked about. We will provide an overview about the different types of information an intelligent robot needs to adaptively and dexterously perform everyday activities. In our framework, every time a robot performs an activity, it creates an episodic memory. It can also acquire experiences from mental simulations, learn from these real and simulated experiences, and share them with other robots through dedicated knowledge web services.

The electronic structure of non-Kramers ${\mathrm{Tb}}^{3+}$ centers in single crystals of yttrium aluminum garnet (YAG) was studied using a new-generation high-frequency magnetic resonance spectrometer that allows measurements of electron paramagnetic resonance (EPR), electron spin echo (ESE), the photon echo on hyperfine components of Stark levels in zero magnetic field, and optically detected magnetic resonance (ODMR). It was created on the basis of a highly stable microwave bridge operating in the near-terahertz region (0.094 or 0.130 THz), both in continuous-wave (cw) and pulse modes, a nonresonant system for supplying microwave power to a sample, and a cryogen-free magneto-optical cryostat. EPR, ESE, and cw measurements at two frequencies allowed us to reliably and with high accuracy determine the parameters of ${\mathrm{Tb}}^{3+}$ centers that occupy yttrium dodecahedral positions in YAG: ${g}_{||}=15.8\ifmmode\pm\else\textpm\fi{}0.2$, ${g}_{\ensuremath{\perp}}\ensuremath{\approx}0$ (|| corresponds to one of the $\ensuremath{\langle}100\ensuremath{\rangle}$ crystal axes), the zero-field splitting $\mathrm{\ensuremath{\Delta}}=2.705\ifmmode\pm\else\textpm\fi{}0.005\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$, and the hyperfine interaction constant $A=0.197\ifmmode\pm\else\textpm\fi{}0.005\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$. In addition to the ${\mathrm{Tb}}^{3+}$ centers in a regular environment, EPR spectra with lower intensity and a resolved hyperfine structure were found for at least three types of additional ${\mathrm{Tb}}^{3+}$ centers. They have symmetry, $g$ factors, and hyperfine interaction constants which are close to those of the main ${\mathrm{Tb}}^{3+}$ centers but differ in the zero-field splitting parameters \ensuremath{\Delta} that strongly depend on the crystal field. They were ascribed to ${\mathrm{Tb}}^{3+}$ centers with nearby antisite ${\mathrm{Y}}_{\mathrm{Al}}$ defects. Similarity with several types of ${\mathrm{Ce}}^{3+}$ centers in YAG crystals, the types, and relative concentrations of antisite defects are discussed. For one of the additional ${\mathrm{Tb}}^{3+}$ centers, splitting of the energy levels in the zero field turned out to be close to an energy of 94 GHz microwave quanta, and intense echo signals were observed in weak magnetic fields and in the zero field corresponding to the EPR transitions between the hyperfine components of the ${\mathrm{Tb}}^{3+}$ spin levels. ODMR spectra of ${\mathrm{Tb}}^{3+}$ centers in YAG crystals, containing Ce and Tb, were obtained by monitoring the intensity of the ${\mathrm{Ce}}^{3+}$ luminescence, which implies the transfer of energy from ${\mathrm{Tb}}^{3+}$ ions to ${\mathrm{Ce}}^{3+}$ ions with conservation of spin. This result seems to be important, since these systems are of interest for quantum communication and computations. Taking into account that cerium does not have isotopes with a nuclear spin and that terbium has 100% $^{159}\mathrm{Tb}$ having nuclear spin $I=3/2$ and a sufficiently large nuclear magnetic moment, the ${\mathrm{Tb}}^{3+}\ensuremath{-}{\mathrm{Ce}}^{3+}$ system in garnet crystals can be promising for coherent information processing. ${\mathrm{Tb}}^{3+}$ ions can play a role of qubits and ${\mathrm{Ce}}^{3+}$ ion with a lifetime of about 50 ns, and almost unity quantum efficiency of optical transitions can be used as a single-ion readout arrangement. The prospects for using this system as hardware for quantum communication and computations are discussed.

36 pages, 7 figures, second version extending [v1] Submitted to IEEE Transactions on Informations Theory; International audience; We provide a purely quantum version of polar codes, achieving the coherent information of any quantum channel. Our scheme relies on a recursive channel combining and splitting construction, where a two-qubit gate randomly chosen from the Clifford group is used to combine two single-qubit channels. The inputs to the synthesized bad channels are frozen by preshared EPR pairs between the sender and the receiver, so our scheme is entanglement assisted. We further show that quantum polarization can be achieved by choosing the channel combining Clifford operator randomly, from a much smaller subset of only 9 two-qubit Clifford gates. Subsequently, we show that a Pauli channel polarizes if and only if a specific classical channel over four symbol input set polarizes. We exploit this equivalence to prove fast polarization for Pauli channels, and to devise an efficient successive cancellation based decoding algorithm for such channels. Finally, we present a code construction based on chaining several quantum polar codes, which is shown to require a rate of preshared entanglement that vanishes asymptotically.

Information systems support organizations to achieve strategic competitiveness and to improve the decision-making process. In addition, they help timely implementation of projects and effective risk management. A reliable and coherent information system requires a solid security framework that ensures Confidentiality, Integrity, Availability, Authenticity and Auditability of the critical information assets; therefore, managing security is essential for organizations doing a business in a globally networked and competitive environment whilst seeking to achieve their objectives and goals and ensuring the continuity of business. To date, studies have shown that non-technical risks are as important as technical risks in safeguarding. However, little attention has been paid to the role of human factors or organizational factors. This study validates the importance of non-technical factors based on a case study of an incident analysis using the information security framework with a focus of non-technical factors.

Cavity magnon polaritons are mixed quasiparticles that arise from the strong coupling between cavity photons and quantized magnons. Combining high-speed photons with long-coherence-time magnons, such polaritons promise to be a potential candidate for quantum information processing. For harnessing coherent information contained in spatially distributed polariton states, it is highly desirable to manipulate cavity magnon polaritons in a two-dimensional system. Here, we demonstrate that tunable cavity magnon polariton transport can be achieved by strongly coupling magnons to microwave photons in a cross-cavity. An analog to the dynamic Hall effect has been demonstrated in a planar cavity spintronic device, where the propagation of cavity-magnon-polaritons is deflected transversally due to hybrid magnon-photon dynamics. Implementing this device as a Michelson-type interferometer using the coherent nature of the dynamic Hall and longitudinal signals, we have developed a proof-of-principle logic device to control the amplitude of cavity-magnon-polaritons by encoding the input microwave phase., Exploring photon-polariton interactions advances not only the understanding of polariton dynamics but also the modern technologies. Here the authors take advantage of strong coupled magnons and microwave photons in a cross-cavity to achieve tunable cavity magnon polariton transport which can be potentially applied as logic devices.

In this paper, a deep learning approach for detecting pavement distress from nonideal photographic images of the road is investigated. Due to inconsistent data quality, part of the associated machine learning challenge is to produce training and validation data that bears coherent information sufficient for the task of successfully training a deep convolutional neural network that provides required detection performance. In the paper, the proposed method for detecting pavement distress is described. Work-in-progress experimental results are reported and analyzed.

We provide a purely quantum version of polar codes, achieving the symmetric coherent information of any qubit-input quantum channel. Our scheme relies on a recursive channel combining and splitting construction, where a two-qubit gate randomly chosen from the Clifford group is used to combine two single-qubit channels. The inputs to the synthesized bad channels are frozen by preshared EPR pairs between the sender and the receiver, so our scheme is entanglement assisted. We further show that quantum polarization can be achieved by choosing the channel combining Clifford operator randomly, from a much smaller subset of only nine two-qubit Clifford gates. Subsequently, we show that a Pauli channel polarizes if and only if a specific classical channel over a four-symbol input set polarizes. We exploit this equivalence to prove fast polarization for Pauli channels, and to devise an efficient successive cancellation based decoding algorithm for such channels. Finally, we present a code construction based on chaining several quantum polar codes, which is shown to require a rate of preshared entanglement that vanishes asymptotically., 38 pages, 6 figures

All-optical encryption of information in fibre telecommunication networks offers lower complexity and far higher data rates than electronic encryption can deliver. However, existing optical layer encryption methods, which are compatible with keys of unlimited length, are based on nonlinear processes that require intense optical fields. Here, we introduce an optical layer secure communication protocol that does not rely on nonlinear optical processes but instead uses energy redistribution of coherent optical waves interacting on a plasmonic metamaterial absorber. We implement the protocol in a telecommunication optical fibre information network, where signal and key distribution lines use a common coherent information carrier. We investigate and demonstrate different encryption modes, including a scheme providing perfect secrecy. All-optical cryptography, as demonstrated here, exploits signal processing mechanisms that can satisfy optical telecom data rate requirements in any current or next-generation frequency band with bandwidth exceeding 100 THz and a switching energy of a few photons per bit. This is the first demonstration of an optical telecommunications application of metamaterial technology. MOE (Min. of Education, S’pore) Published version

Activation of quantum capacity is a surprising phenomenon according to which the quantum capacity of a certain channel may increase by combining it with another channel with zero quantum capacity. Superactivation describes an even more particular occurrence, in which both channels have zero quantum capacity, but their composition has a nonvanishing one. We investigate these effects for all single-mode phase-insensitive Gaussian channels, which include thermal attenuators and amplifiers, assisted by a two-mode positive-partial-transpose channel. Our result shows that activation phenomena are special but not uncommon. We can reveal superactivation in a broad range of thermal attenuator channels, even when the transmissivity is quite low. This means that we can transmit quantum information reliably through very noisy Gaussian channels having zero quantum capacity. We further show that no superactivation is possible for entanglement-breaking Gaussian channels in physically relevant circumstances by proving the non-activation property of the coherent information of bosonic entanglement-breaking channels with finite input energy., 11 pages, 2 figures; minor changes, references are added

Information systems support organizations to achieve strategic competitiveness over other organizations and assist senior management in the decision-making process. In addition, they help organizations in timely implementation of projects and effective risk management. A reliable and coherent Information System requires a solid security framework that ensures Confidentiality, Integrity, Availability, Authenticity and Auditability of the critical information assets; therefore, managing security is essential for organizations doing business in a globally networked and competitive environment whilst seeking to achieve their objectives and goals and ensuring the continuity of business. This paper provides an integrated framework that classifies and holistic view of challenges in Information Security Systems, and their interrelationships. The framework is expected to provide a basis that can be used to evaluate individual organizational members' behavior and the adequateness of existing security measures. Scopus

The decoherence of quantum states defines the transition between the quantum world and classical physics. Decoherence or, analogously, quantum mechanical collapse events pose fundamental questions regarding the interpretation of quantum mechanics and are technologically relevant because they limit the coherent information processing performed by quantum computers. We have discovered that the transition regime enables a novel type of matter transport. Applying this discovery, we present nanoscale devices in which decoherence, modeled by random quantum jumps, produces fundamentally novel phenomena by interrupting the unitary dynamics of electron wave packets. Noncentrosymmetric conductors with mesoscopic length scales act as two-terminal rectifiers with unique properties. In these devices, the inelastic interaction of itinerant electrons with impurities acting as electron trapping centers leads to a novel steady state characterized by partial charge separation between the two leads, or, in closed circuits to the generation of persistent currents. The interface between the quantum and the classical worlds therefore provides a novel transport regime of value for the realization of a new category of mesoscopic electronic devices., Comment: 10 pages, 7 figures

Filling large missing regions of an image with semantically meaningful and visually coherent information is a challenging task. Traditional approaches use textures from surrounding pixels for filling in the missing patches and are suitable for filling the missing data with a generic background. The dataset provided in the ECCV’18 Satellite Workshop Chalearn LAP Inpainting Competition Track 1-Inpainting of still images of humans contains masked images with randomly placed square masks, occluding up to 70% of the image data. The masks are human-centered. In order to inpaint the human-centric images, we use a generative model which can generate patches that do not appear anywhere in the image. This allows it to complete images with detailed features like faces. Our model can inpaint images with multiple holes of different sizes at various locations and can handle a wide variety of scenes. Our model produces decent results in reconstructing not only the occluded human parts but also the background. Most of our work is inspired by previous work on Image Generation and Image Inpainting.

To extend the classical concept of Markovianity to an open quantum system, different notions of the divisibility of its dynamics have been introduced. Here we analyze this issue by five complementary approaches: equations of motion, real-time diagrammatics, Kraus-operator sums, as well as time-local (TCL) and nonlocal (Nakajima-Zwanzig) quantum master equations. As a case study featuring several types of divisible dynamics, we examine in detail an exactly solvable noninteracting fermionic resonant level coupled arbitrarily strongly to a fermionic bath at arbitrary temperature in the wideband limit. In particular, the impact of divisibility on the time-dependence of the observable level occupation is investigated and compared with typical Markovian approximations. We find that the loss of semigroup-divisibility is accompanied by a prominent reentrant behavior: Counter to intuition, the level occupation may temporarily \emph{increase} significantly in order to reach a stationary state with \emph{smaller} occupation, implying a reversal of the measurable transport current. In contrast, the loss of the so-called completely-positive divisibility is more subtly signaled by the \emph{prohibition} of such current reversals in specific time-intervals. Experimentally, it can be detected in the family of transient currents obtained by varying the initial occupation. To quantify the nonzero footprint left by the system in its effective environment, we determine the exact time-dependent state of the latter as well as related information measures such as entropy, exchange entropy and coherent information., Comment: Submitted to The Journal of Chemical Physics, 19 pages + 14 pages of appendices with 13 figures. Significantly extended introduction and discussion, no results changed

The interaction between magnetic and acoustic excitations have recently inspired many interdisciplinary studies ranging from fundamental physics to circuit implementation. Specifically, the exploration of their coherent interconversion enabled via the magnetoelastic coupling opens a new playground combining straintronics and spintronics, and provides a unique platform for building up on-chip coherent information processing networks with miniaturized magnonic and acoustic devices. In this Perspective, we will focus on the recent progress of magnon-phonon coupled dynamic systems, including materials, circuits, imaging and new physics. In particular, we highlight the unique features such as nonreciprocal acoustic wave propagation and strong coupling between magnons and phonons in magnetic thin-film systems, which provides a unique platform for their coherent manipulation and transduction. We will also review the frontier of surface acoustic wave resonators in coherent quantum transduction and discuss how the novel acoustic circuit design can be applied in microwave spintronics., Comment: in press in APL Materials as a perspective paper

This paper will explore the restriction of the coherent information to the positive definite density matrices in the special case where the quantum channels are strictly positive linear maps. The space of positive definite density matrices is equipped with an embedded submanifold structure of the real vector space of Hermitian matrices. These ensure that the n-shot coherent information is differentiable and allows for the computation of its gradient and Hessian. We show that any tensor products of critical points preserve being a critical point of the coherent information. Furthermore, we show that for any positive integer n, the maximally mixed state is always a critical point for the class of mixed unitary quantum channels with orthogonal, unitary Kraus operators. We determine when the maximally mixed state is a local maximum/minimum or saddle point, including its eigenvectors, for the class of Pauli-erasure channels when n is equal to 1. This class includes the dephrasure channel and Pauli channel and refines potential regions where super-additivity is thought to occur. These techniques can be used to study other optimization problems over density matrices and allow the use of manifold optimization algorithms and a better understanding of the quantum capacity problem by utilizing the first and second order geometry.

The similarities between biological and physical systems as respectively defined in quantum information biology (QIB) and in a Darwinian approach to quantum mechanics (DAQM) have been analysed. In both theories the processing of information is a central feature characterising the systems. The analysis highlights a mutual support on the thesis contended by each theory. On the one hand, DAQM provides a physical basis that might explain the key role played by quantum information at the macroscopic level for bio-systems in QIB. On the other hand, QIB offers the possibility, acting as a macroscopic testing ground, to analyse the emergence of quantumness from classicality in the terms held by DAQM. As an added result of the comparison, a tentative definition of quantum information in terms of classical information flows has been proposed. The quantum formalism would appear from this comparative analysis between QIB and DAQM as an optimal information scheme that would maximise the stability of biological and physical systems at any scale.

Models of cognition and decision making based on quantum theory have been the subject of much interest recently. Quantum theory provides an alternative probabilistic framework for modelling decision making compared with classical probability theory, and has been successfully used to address behaviour considered paradoxical or irrational from a classical point of view.\ud \ud The purpose of this tutorial is to give an introduction to quantum models, with a particular emphasis on how to build these models in practice. Examples are provided by the study of order effects on judgements, and we will show how order effects arise from the structure of the theory. In particular, we show how to derive the recent discovery of a particular constraint on order effects implied by quantum models, called the Quantum Question (QQ) Equality, which does not appear to be derivable from alternative accounts, and which has been experimentally verified to high precision. However the general theory and methods of model construction we will describe are applicable to any quantum cognitive model. Our hope is that this tutorial will give researchers the confidence to construct simple quantum models of their own, particularly with a view to testing these against existing cognitive theories.

We prove basic facts about the properties of atomicity and coherence for Scott information systems, and we establish direct connections between coherent information systems and well-known point-free structures.

In order to improve the efficiency of quantum secret sharing, quantum ramp secret sharing schemes were proposed (Ogawa et al., Phys. Rev. A 72, 032318 [2005]), which had a trade-off between security and coding efficiency. In quantum ramp secret sharing, partial information about the secret is allowed to leak to a set of participants, called an intermediate set, which cannot fully reconstruct the secret. This paper revisits the size of a share in the quantum ramp secret scheme based on a relation between the quantum operations and the coherent information. We also propose an optimal quantum ramp secret sharing scheme.

We propose a model of parties’ dynamical decision-making related to becoming a member of a coalition or pursuing a competitive strategy. Our approach is based on the mathematical formalism of quantum information theory. The devised model has no direct relation to quantum physics, only its mathematical apparatus and methodology are applied, in particular the quantum probability and the theory of open quantum systems. The latter describes the most general form of adaptive dynamics of a system interacting with an environment. In our model the environment is composed of the electorate, or more specifically the informational bath generated by the parties’ electorate, which is a key part of the socio-economic context surrounding the political party as a decision-making entity. The key feature of the quantum model is the ability to capture the strong interrelation of the parties’ decision making states, through the notion of entanglement. The preferences of different parties evolve simultaneously and non-separably in the joint information space. We model the approaching of the state of political equilibrium by using the Markov approximation of the quantum master equation. Illustrative examples of numerical simulations are presented to specify, how the model works operationally.

In this article, we show the mythical relationship between science and information. Since every substance has a price-tag or price-tags of information which includes all the building blocks in our universe, one can not simply ignore information when dealing with science. We have shown that there is a profound connection between information and entropy, a quantity that has been well accepted in science. Without this connection, information would be more difficult to apply to science. Two of the most important pillars in modern physics must be the Einstein's relativity theory and the Schrodinger's quantum mechanics. We show that there exists a profound relationship between them, by means of the uncertainty principle. In due of the uncertainty relation, we show that every bit of information takes time and energy to transfer, to create and to observe. Since one cannot create something from nothing, we show that, anything to be created needs a huge amount of energy and requires a great deal of entropy to make it happen! My question is that, can we afford it?

In a preceding publication a fundamentally oriented and irreversible world was shown to be derivable from the important principle of least action. A consequence of such a paradigm change is avoidance of paradoxes within a “dynamic” quantum physics. This becomes essentially possible because fundamental irreversibility allows consideration of the “entropy” concept in elementary processes. For this reason, and for a compensation of entropy in the spread out energy of the wave, the duality of particle and wave has to be mediated via an information self-image of matter. In this publication considerations are extended to irreversible thermodynamics, to gravitation and cosmology with its dependence on quantum interpretations. The information self-image of matter around particles could be identified with gravitation. Because information can also impose an always constant light velocity there is no need any more to attribute such a property to empty space, as done in relativity theory. In addition, the possibility is recognized to consider entropy generation by expanding photon fields in the universe. Via a continuous activation of information on matter photons can generate entropy and release small energy packages without interacting with matter. This facilitates a new interpretation of galactic redshift, emphasizes an information link between quantum- and cosmological phenomena, and evidences an information-triggered origin of the universe. Self-organized processes approach maximum entropy production within their constraints. In a far from equilibrium world also information, with its energy content, can self-organize to a higher hierarchy of computation. It is here identified with consciousness. This appears to explain evolution of spirit and intelligence on a materialistic basis. Also gravitation, here identified as information on matter, could, under special conditions, self-organize to act as a super-gravitation, offering an alternative to dark matter. Time is not an illusion, but has to be understood as flux of action, which is the ultimate reality of change. The concept of an irreversible physical world opens a route towards a rational understanding of complex contexts in nature.

Hybrid dynamic systems have recently gained interests with respect to both fundamental physics and device applications, particularly with their potential for coherent information processing. In this perspective, we will focus on the recent rapid developments of magnon-based hybrid systems, which seek to combine magnonic excitations with diverse excitations for transformative applications in devices, circuits and information processing. Key to their promising potentials is that magnons are highly tunable excitations and can be easily engineered to couple with various dynamic media and platforms. The capability of reaching strong coupling with many different excitations has positioned magnons well for studying solid-state coherent dynamics and exploiting unique functionality. In addition, with their gigahertz frequency bandwidth and the ease of fabrication and miniaturization, magnonic devices and systems can be conveniently integrated into microwave circuits for mimicking a broad range of device concepts that have been applied in microwave electronics, photonics and quantum information. We will discuss a few potential directions for advancing magnon hybrid systems, including on-chip geometry, novel coherent magnonic functionality, and coherent transduction between different platforms. As future outlook, we will discuss the opportunities and challenges of magnonic hybrid systems for their applications in quantum information and magnonic logic., Comment: 15 pages, 10 figures

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 it hard to understand the quantum capacity of all but very special channels. In this paper, we consider the dephrasure channel, which is the concatenation of a dephasing channel and an erasure channel. This very simple channel displays remarkably rich and exotic properties: we find nonadditivity of coherent information at the two-letter level, a big gap between single-letter coherent and private informations, and positive quantum capacity for all complementary channels. Its clean form simplifies the evaluation of coherent information substantially and, as such, we hope that the dephrasure channel will provide a much-needed laboratory for the testing of new ideas about nonadditivity., 16 pages, 7 figures; comments welcome! v3: fixed minor typos, added analytical proof that determines threshold of single-letter coherent information and repetition codes

Funder: Draper’s Company Research Fellowship, We examine the usefulness of applying neural networks as a variational state ansatz for many-body quantum systems in the context of quantum information-processing tasks. In the neural network state ansatz, the complex amplitude function of a quantum state is computed by a neural network. The resulting multipartite entanglement structure captured by this ansatz has proven rich enough to describe the ground states and unitary dynamics of various physical systems of interest. In the present paper, we initiate the study of neural network states in quantum information-processing tasks. We demonstrate that neural network states are capable of efficiently representing quantum codes for quantum information transmission and quantum error correction, supplying further evidence for the usefulness of neural network states to describe multipartite entanglement. In particular, we show the following main results: (a) neural network states yield quantum codes with a high coherent information for two important quantum channels, the generalized amplitude damping channel and the dephrasure channel. These codes outperform all other known codes for these channels, and cannot be found using a direct parametrization of the quantum state. (b) For the depolarizing channel, the neural network state ansatz reliably finds the best known codes given by repetition codes. (c) Neural network states can be used to represent absolutely maximally entangled states, a special type of quantum error-correcting codes. In all three cases, the neural network state ansatz provides an efficient and versatile means as a variational parametrization of these highly entangled states.

Energy-efficient ultrafast all-optical signal processing may contribute to solving growing bandwidth and energy challenges in optical telecommunications. However, conventional solutions for all-optical data processing rely on nonlinear optical materials with inherent minimum power requirements and trade-offs between bandwidth and speed. In contrast, the coherent interaction of light-with-light in an absorber of nanoscale thickness can facilitate high-contrast modulation of one optical signal with another, ultimately with few-femtosecond response times and at arbitrarily low (even single photon) intensities. We report here on the first demonstration of a fiberized metamaterial device for all-optical signal processing based upon coherent modulation of absorption. The integrated metadevice is based on a plasmonic metamaterial of nanoscale thickness fabricated on the core area of a single-mode optical fibre, and designed to operate over the 1530 – 1565 nm telecoms wavelength range. We demonstrate signal processing operations analogous to logical NOT, XOR and AND functions at effective rates from tens of kbit/s up to 40 Gbit/s with energy consumption as low as 2.5 fJ/bit, as well as selective absorption and transmission of picosecond pulses and the generation of 1 ps ‘dark pulses’. We anticipate that such metadevices, with THz bandwidth, may provide solutions for quantum information networks as well as orders-of-magnitude improvements in speed and energy consumption over existing nonlinear approaches to all-optical signal processing in coherent information networks.

We extend a recent method to detect lower bounds to the quantum capacity of quantum communication channels by considering realistic scenarios with general input probe states and arbitrary detection procedures at the output. Realistic certification relies on a new bound for the coherent information of a quantum channel that can be applied with arbitrary bipartite mixed input states and generalized output measurements., Comment: 7 pages, 2 figures

This paper presents a methodology to detect personality and basic emotion characteristics of crowds in video sequences. Firstly, individuals are detected and tracked, then groups are recognized and characterized. Such information is then mapped to OCEAN dimensions, used to find out personality and emotion in videos, based on OCC emotion models. Although it is a clear challenge to validate our results with real life experiments, we evaluate our method with the available literature information regarding OCEAN values of different Countries and also emergent Personal distance among people. Hence, such analysis refer to cultural differences of each country too. Our results indicate that this model generates coherent information when compared to data provided in available literature, as shown in qualitative and quantitative results.

We develop the resource theory of private randomness extraction in the distributed and device-dependent scenario. We begin by introducing the notion of independent random bits, which are bipartite states containing ideal private randomness for each party, and motivate the natural set of free operations. As a conceptual tool, we introduce Virtual Quantum State Merging, which is essentially the flip side of Quantum State Merging, without communication. We focus on the bipartite case and find the rate regions achievable in different settings. Surprisingly, it turns out that local noise can boost randomness extraction. As a consequence of our analysis, we resolve a long-standing problem by giving an operational interpretation for the reverse coherent information (up to a constant term $\log d$) as the number of private random bits obtained by sending quantum states from one honest party (server) to another one (client) via the eavesdropped quantum channel., Comment: 6+12 pages, 1 figure. Improved presentation, more details in the technical proofs, updated references. Accepted for publication in PRL

Entanglement distillation is a key primitive for distributing high-quality entanglement between remote locations. Probabilistic noiseless linear amplification based on the quantum scissors is a candidate for entanglement distillation from noisy continuous-variable (CV) entangled states. Being a non-Gaussian operation, quantum scissors is challenging to analyze. We present a derivation of the non-Gaussian state heralded by multiple quantum scissors in a pure loss channel with two-mode squeezed vacuum input. We choose the reverse coherent information (RCI)---a proven lower bound on the distillable entanglement of a quantum state under one-way local operations and classical communication (LOCC), as our figure of merit. We evaluate a Gaussian lower bound on the RCI of the heralded state. We show that it can exceed the unlimited two-way LOCCassisted direct transmission entanglement distillation capacity of the pure loss channel. The optimal heralded Gaussian RCI with two quantum scissors is found to be significantly more than that with a single quantum scissors, albeit at the cost of decreased success probability. Our results fortify the possibility of a quantum repeater scheme for CV quantum states using the quantum scissors., Comment: accepted for publication in Physical Review A

This paper investigates simultaneous wireless information and power transfer (SWIPT) in energy harvesting (EH) relay systems. Unlike the existing SWIPT schemes requiring the instantaneous channel state information (CSI) for coherent information delivery, we propose a noncoherent SWIPT framework for decode-and-forward (DF) relay systems bypassing the need for the instantaneous CSI and consequently saving energy in the network. The proposed SWIPT framework embraces both the power-splitting noncoherent DF (PS-NcDF) and time-switching noncoherent DF (TS-NcDF) in a unified form, and supports arbitrary $M$ -ary noncoherent frequency-shift keying (FSK) and differential phase-shift keying (DPSK). The exact (noncoherent) maximum-likelihood detectors (MLDs) for PS-NcDF and TS-NcDF are derived in a unified form, which involves integral evaluations yet serves as the optimum performance benchmark for noncoherent SWIPT. To reduce the computational cost of the exact MLDs, we also propose closed-form approximate MLDs achieving near-optimum performance, thus serving as a practical solution for noncoherent SWIPT. Numerical results demonstrate a performance tradeoff between the first and second hops through the adjustment of time switching or power splitting parameters, whose optimal values minimizing the symbol-error rate (SER) are strictly between 0 and 1. We demonstrate that $M$ -FSK results in a significant energy saving over $M$ -DPSK for $M\ge 8$ ; thus $M$ -FSK may be more suitable for EH relay systems.

We analytically investigate the dynamics of quantum Fisher information of two qubits in independent environments for both uncorrelated and entangled input states. Especially, we observe that, in the non-Markovian regime and resonant case, quantum Fisher information of uncorrelated input state vanishes only at discrete time point whereas that of entangled input state can disappear during finite time interval. It shows that quantum Fisher information, which determines the parameter estimation precision, is strongly affected by the environment memory effects, and the advantage of entanglement-enhance metrology no longer exists even for a very short time. We also note that quantum Fisher information for two kinds of input states can be preserved under appropriate qubit-reservoir detuning.

In this paper we review the general framework of operational probabilistic theories (OPT), along with the six axioms from which quantum theory can be derived. We argue that the OPT framework along with a relaxed version of five of the axioms, define a general information theory. We close the paper with considerations about the role of the observer in an OPT, and the interpretation of the von Neumann postulate and the Schrodinger-cat paradox.

The mutual information has been successfully used as a measure of correlation strength between quantum systems, especially for bipartite systems. Here, we examine the use of this measure for multipartite quantum systems. For system of qubits, we find that the difference between `classical' and `quantum' regimes of correlation strength amounts to just 1 bit of information, at most. We show that the information content of a correlation can be expanded into correlations between pairwise components and demonstrate that in terms of this information-based measure of correlation the GHZ states are the only states that simultaneously optimise these pairwise correlations for systems of qubits.

Nowadays, one of the main challenges in factory planning is the consistent and coherent information modelling along planning processes. Despite the current efforts in the fields of virtual production as well as digital and virtual factory, planning and simulation applications mostly support only the analysis and the optimisation of single planning aspects. However, to match nowadays challenges, planners require solutions that provide an integrated view to evaluate planning scenarios in advance and to achieve increasing production quality and efficiency. The concept of virtual production intelligence (VPI) provides a basic concept for such an integrative information system that enables planners to integrate, to aggregate and to analyse data gathered during one planning project as well as to compare different projects. In this study, we present such an information system for factory planning using the concept of the VPI. The focus lies in particular on the information modelling as well as the information in...

The resultant measures of the entropy/information content in complex elec- tronic states are discussed in the canonical position and momentum representations of molecular quantum mechanics. The nonclassical (phase/current) supplements of the classical (probability) descriptors of the overall entropy/information content in electronic states are identified and the associated entropy deficiency (information dis- tance) quantities are introduced. The Shannon (global, logarithmic) and Fisher (local, gradient) information descriptors in both spaces are summarized, and the momentum continuity equation is used to establish the associated probability source. General relations between global and local information densities are examined and the etropic principles determining molecular phase equilibria are investigated.

Quantum channels are trace-preserving completely positive linear maps between Banach spaces of trace-class operators (Schatten classes of order 1); these are noncommutative analogs of Markov operators in classical probability theory. They also play the role of dynamical maps in quantum theory [1, Chap. 6]. The main characteristics determining the information properties of a quantum channel include its classical entanglement-assisted and unassisted capacities. The classical (unassisted) capacity C(Φ) of a channel Φ determines the limit rate of classical information transmission through Φ with any block coding at the input and the corresponding measurement at the output, and the classical entanglement-assisted channel capacity Cea(Φ) supposes, in addition, the presence of an entangled state between the input and the output of the channel Φ (a detailed description of transmission protocols can be found in [1, Chap. 8]). Since entanglement is an additional resource, it follows that Cea(Φ) ≥ C(Φ) for any channel Φ. LetH be a separable Hilbert space. By T(H) we denote the Banach space of all trace-class operators onH and byS(H), the subset of T(H) consisting of all positive operators with trace 1; we refer to such operators as quantum states and denote them by Greek letters ρ, σ, . . . . We denote a set of quantum states {ρi} with probability distributions {πi} by {πi, ρi} and call it an ensemble of states; the state ρ = ∑ i πiρi is called the average state of the ensemble {πi, ρi}. A quantum channel is a trace-preserving completely positive linear map Φ: T(HA) → T(HB) [1, Chap. 6]. Let H(ρ) be the von Neumann entropy of a state ρ, and let H(ρ‖σ) be the quantum relative entropy of states ρ and σ. For a given channel Φ and any ensemble {πi, ρi} of input quantum states, the output χ-quantity is determined by the expression

Quantum degenerate code may improve the hashing bound of quantum capacity. We propose a family of quantum degenerate codes derived from two-colorable graphs. The coherent information of the codes is analytically obtained as a function of the channel noise for the depolarizing channel. We find a new code which has a higher noise threshold than that of the repetition code.

The use of information technology in the study of human behavior is a subject of great scientific interest. Cultural and personality aspects are factors that influence how people interact with one another in a crowd. This paper presents a methodology to detect cultural characteristics of crowds in video sequences. Based on filmed sequences, pedestrians are detected, tracked and characterized. Such information is then used to find out cultural differences in those videos, based on the Big-five personality model. Regarding cultural differences of each country, results indicate that this model generates coherent information when compared to data provided in literature.

The computer architecture for the neural-network control system with a synchronous peripheral subsystem allows transmitting information about the state of the control object and its environment with maximum accuracy. Synchronization between executive resources eliminates restrictions on the interaction between the components of complex control objects. This problem used to be able to be solved only by breaking the problem into slightly dependent smaller tasks. The proposed model is a coherent information environment for neural-network control system, with simultaneous record mode of the object state parameters. This mode is important for the control systems objects with unidentified degrees of freedom – typical field of applications of neural systems. The proposed model of the synchronous information environment is necessary even the control system is implemented with a fixed algorithm.

We establish uncertainty relations between information loss in general open quantum systems and the amount of non-ergodicity of the corresponding dynamics. The relations hold for arbitrary quantum systems interacting with an arbitrary quantum environment. The elements of the uncertainty relations are quantified via distance measures on the space of quantum density matrices. The relations hold for arbitrary distance measures satisfying a set of intuitively satisfactory axioms. The relations show that as the non-ergodicity of the dynamics increases, the lower bound on information loss decreases, which validates the belief that non-ergodicity plays an important role in preserving information of quantum states undergoing lossy evolution. We also consider a model of a central qubit interacting with a fermionic thermal bath and derive its reduced dynamics, to subsequently investigate the information loss and nonergodicity in such dynamics. We comment on the minimal situations that saturate the uncertainty relations., 8 pages, 6 figures

We investigate the properties of two particular sets of separable two-qubit states with maximally mixed marginals, named parallel states and antiparallel states respectively. Although these two sets of states are prepared by the same type of quantum operations acting on classically correlated states with equal classical correlations, they share different properties. By comparing two fundamental figures of merit based on quantum correlations and quantum Fisher information for accessing information quality, the superiority of parallel states over antiparallel ones is investigated. This is different from the previous results that antiparallel state turns out to be more effective in the tasks such as sending unknown direction information. The amount of the information that can be extracted from the local measurements is also presented, which turns out to be the same for these two states. This work reveals new aspects of information encoding and extraction problem.

Optical communication channels are ultimately quantum-mechanical in nature, and we must therefore look beyond classical information theory to determine their communication capacity as well as to find efficient encoding and decoding schemes of the highest rates. Thermal channels, which arise from linear coupling of the field to a thermal environment, are of particular practical relevance; their classical capacity has been recently established, but their quantum capacity remains unknown. While the capacity sets the ultimate limit on reliable communication rates, it does not promise that such rates are achievable by practical means. Here we construct efficiently encodable codes for thermal channels which achieve the classical capacity and the so-called Gaussian coherent information for transmission of classical and quantum information, respectively. Our codes are based on combining polar codes with a discretization of the channel input into a finite "constellation" of coherent states. Encoding of classical information can be done using linear optics., v3: published version; v2: vastly improved presentation. Figures! v1: 10 pages

Transmitted complexity (mutual entropy) is one of the important measures for quantum information theory developed recently in several ways. We will review the fundamental concepts of the Kossakowski, Ohya and Watanabe entropy and define a transmitted complexity for quantum dynamical systems. This article is part of the themed issue ‘Second quantum revolution: foundational questions’.