Showing papers on "Coherent information published in 2014"
TL;DR: The study of memory effects in quantum channels is a fertile ground where interesting novel phenomena emerge at the intersection of quantum information theory and other branches of physics.
Abstract: Any physical process can be represented as a quantum channel mapping an initial state to a final state. Hence it can be characterized from the point of view of communication theory, i.e., in terms of its ability to transfer information. Quantum information provides a theoretical framework and the proper mathematical tools to accomplish this. In this context the notion of codes and communication capacities have been introduced by generalizing them from the classical Shannon theory of information transmission and error correction. The underlying assumption of this approach is to consider the channel not as acting on a single system, but on sequences of systems, which, when properly initialized allow one to overcome the noisy effects induced by the physical process under consideration. While most of the work produced so far has been focused on the case in which a given channel transformation acts identically and independently on the various elements of the sequence (memoryless configuration in jargon), correlated error models appear to be a more realistic way to approach the problem. A slightly different, yet conceptually related, notion of correlated errors applies to a single quantum system which evolves continuously in time under the influence of an external disturbance which acts on it in a non-Markovian fashion. This leads to the study of memory effects in quantum channels: a fertile ground where interesting novel phenomena emerge at the intersection of quantum information theory and other branches of physics. A survey is taken of the field of quantum channels theory while also embracing these specific and complex settings.
310 citations
TL;DR: In this article, the role of information exchange in the non-Markovian behavior of dynamical quantum processes following the decoherence approach is discussed, where a quantum system is initially correlated with its measurement apparatus, which in turn interacts with the environment.
Abstract: Exchange of information between a quantum system and its surrounding environment plays a fundamental role in the study of the dynamics of open quantum systems. Here we discuss the role of the information exchange in the non-Markovian behavior of dynamical quantum processes following the decoherence approach, where we consider a quantum system that is initially correlated with its measurement apparatus, which in turn interacts with the environment. We introduce a way of looking at the information exchange between the system and environment using the quantum loss, which is shown to be closely related to the measure of non-Markovianity based on the quantum mutual information. We also extend the results of Fanchini et al. [Phys. Rev. Lett. 112, 210402 (2014)] in several directions, providing a more detailed investigation of the use of the accessible information for quantifying the backflow of information from the environment to the system. Moreover, we reveal a clear conceptual relation between the entanglement- and mutual-information-based measures of non-Markovianity in terms of the quantum loss and accessible information. We compare different ways of studying the information flow in two theoretical examples. We also present experimental results on the investigation of the quantum loss and accessible information for a two-level system undergoing a zero temperature amplitude damping process. We use an optical approach that allows full access to the state of the environment.
86 citations
TL;DR: It is demonstrated that different smoothed definitions of Max-information are essentially equivalent, which allows us to derive new chain rules for the max-information in terms of min- and max-entropies, thus extending the smooth entropy formalism to mutual information.
Abstract: We study formal properties of smooth max-information, a generalization of von Neumann mutual information derived from the max-relative entropy. Recent work suggests that it is a useful quantity in one-shot channel coding, quantum rate distortion theory, and the physics of quantum many-body systems. Max-information can be defined in multiple ways. We demonstrate that different smoothed definitions are essentially equivalent (up to logarithmic terms in the smoothing parameters). These equivalence relations allow us to derive new chain rules for the max-information in terms of min- and max-entropies, thus extending the smooth entropy formalism to mutual information.
65 citations
TL;DR: The quantum generalisation of the skew divergence is studied, which is a dissimilarity measure between distributions introduced by Lee in the context of natural language processing and presents a number of important applications.
Abstract: In this paper, we study the quantum generalisation of the skew divergence, which is a dissimilarity measure between distributions introduced by Lee in the context of natural language processing. We provide an in-depth study of the quantum skew divergence, including its relation to other state distinguishability measures. Finally, we present a number of important applications: new continuity inequalities for the quantum Jensen-Shannon divergence and the Holevo information, and a new and short proof of Bravyi's Small Incremental Mixing conjecture.
60 citations
TL;DR: In this paper, the authors show that Renyi mutual information attains operational meaning in the context of composite hypothesis testing, when the null hypothesis is a fixed bipartite state and the alternate hypothesis consists of all product states that share one marginal with the null hypotheses.
Abstract: A variety of new measures of quantum Renyi mutual information and quantum Renyi conditional entropy have recently been proposed, and some of their mathematical properties explored. Here, we show that the Renyi mutual information attains operational meaning in the context of composite hypothesis testing, when the null hypothesis is a fixed bipartite state and the alternate hypothesis consists of all product states that share one marginal with the null hypothesis. This hypothesis testing problem occurs naturally in channel coding, where it corresponds to testing whether a state is the output of a given quantum channel or of a 'useless' channel whose output is decoupled from the environment. Similarly, we establish an operational interpretation of Renyi conditional entropy by choosing an alternative hypothesis that consists of product states that are maximally mixed on one system. Specialized to classical probability distributions, our results also establish an operational interpretation of Renyi mutual information and Renyi conditional entropy.
57 citations
TL;DR: This paper develops the case that there is a plausible underlying reality: one actual spacetime-based history, although with behavior that appears strange when analyzed dynamically (one time-slice at a time), by using a simple model with no dynamical laws.
Abstract: Despite various parallels between quantum states and ordinary information, quantum no-go-theorems have convinced many that there is no realistic framework that might underly quantum theory, no reality that quantum states can represent knowledge about. This paper develops the case that there is a plausible underlying reality: one actual spacetime-based history, although with behavior that appears strange when analyzed dynamically (one time-slice at a time). By using a simple model with no dynamical laws, it becomes evident that this behavior is actually quite natural when analyzed "all-at-once" (as in classical action principles). From this perspective, traditional quantum states would represent incomplete information about possible spacetime histories, conditional on the future measurement geometry. Without dynamical laws imposing additional restrictions, those histories can have a classical probability distribution, where exactly one history can be said to represent an underlying reality.
54 citations
TL;DR: In this article, the mutual information shared between two modes of an entangled state of light was found to advance when one mode propagates through the fast-light medium, and the authors investigated the long-standing question of information velocity in slow and fast light media by measuring the propagation time of random and correlated noise.
Abstract: The long-standing question of information velocity in slow- and fast-light media is investigated by measuring the propagation time of random and correlated noise. The mutual information shared between two modes of an entangled state of light was found to advance when one mode propagates through the fast-light medium.
40 citations
TL;DR: By demonstrating the quantitative bound of the trade-off relations, this work experimentally proves an optimal measurement for estimating quantum systems with minimum disturbance and maximum reversibility and offers fundamental insights on quantum measurement and practical guidelines for implementing various quantum information protocols.
Abstract: Quantum measurement unavoidably disturbs the state of a quantum system if any information about the system is extracted. Recently, the concept of reversing quantum measurement has been introduced and has attracted much attention. Numerous efforts have thus been devoted to understanding the fundamental relation of the amount of information obtained by measurement to either state disturbance or reversibility. Here, we experimentally prove the trade-off relations in quantum measurement with respect to both state disturbance and reversibility. By demonstrating the quantitative bound of the trade-off relations, we realize an optimal measurement for estimating quantum systems with minimum disturbance and maximum reversibility. Our results offer fundamental insights on quantum measurement and practical guidelines for implementing various quantum information protocols.
22 citations
TL;DR: This paper considers the dynamics of quantum systems under a 1 + 1 Robertson–Walker spacetime and finds that the noise imparted to them is equivalent to the well known amplitude damping channel and determines a trade-off between achievable rates of classical and quantum information preservation when entanglement assistance is available.
Abstract: Preserving information stored in a physical system subjected to noise can be modeled in a communication-theoretic paradigm, in which storage and retrieval correspond to an input encoding and output decoding, respectively. The encoding and decoding are then constructed in such a way as to protect against the action of a given noisy quantum channel. This paper considers the situation in which the noise is not due to technological imperfections, but rather to the physical laws governing the evolution of the Universe. In particular, we consider the dynamics of quantum systems under a 1 + 1 Robertson–Walker spacetime and find that the noise imparted to them is equivalent to the well known amplitude damping channel. Since one might be interested in preserving both classical and quantum information in such a scenario, we study trade-off coding strategies and determine a region of achievable rates for the preservation of both kinds of information. For applications beyond the physical setting studied here, we also determine a trade-off between achievable rates of classical and quantum information preservation when entanglement assistance is available.
21 citations
TL;DR: This work provides lower bounds on the entropy of 2-design ensembles and measurements, from which upper bounds on their accessible information and informational power follow, as a function of the dimension only.
Abstract: The accessible information and the informational power quantify the amount of information extractable from a quantum ensemble and by a quantum measurement, respectively. So-called spherical quantum 2-designs constitute a class of ensembles and measurements relevant in testing entropic uncertainty relations, quantum cryptography, and quantum tomography. We provide lower bounds on the entropy of 2-design ensembles and measurements, from which upper bounds on their accessible information and informational power follow, as a function of the dimension only. We show that the statistics generated by 2-designs, although optimal for the abovementioned protocols, never contains more than one bit of information. Finally, we specialize our results to the relevant cases of symmetric informationally complete (SIC) sets and maximal sets of mutually unbiased bases (MUBs), and we generalize them to the arbitrary-rank case.
20 citations
TL;DR: It is proved that many of these generalizations of the conditional mutual information satisfy non-negativity, duality, and monotonicity with respect to local operations on one of the systems $A$ or $B$ (with it being left as an open question to prove that monotoniticity holds withrespect to local Operations on both systems).
Abstract: The conditional quantum mutual information $I(A;B|C)$ of a tripartite state $\rho_{ABC}$ is an information quantity which lies at the center of many problems in quantum information theory. Three of its main properties are that it is non-negative for any tripartite state, that it decreases under local operations applied to systems $A$ and $B$, and that it obeys the duality relation $I(A;B|C)=I(A;B|D)$ for a four-party pure state on systems $ABCD$. The conditional mutual information also underlies the squashed entanglement, an entanglement measure that satisfies all of the axioms desired for an entanglement measure. As such, it has been an open question to find Renyi generalizations of the conditional mutual information, that would allow for a deeper understanding of the original quantity and find applications beyond the traditional memoryless setting of quantum information theory. The present paper addresses this question, by defining different $\alpha$-Renyi generalizations $I_{\alpha}(A;B|C)$ of the conditional mutual information, some of which we can prove converge to the conditional mutual information in the limit $\alpha\rightarrow1$. Furthermore, we prove that many of these generalizations satisfy non-negativity, duality, and monotonicity with respect to local operations on one of the systems $A$ or $B$ (with it being left as an open question to prove that monotoniticity holds with respect to local operations on both systems). The quantities defined here should find applications in quantum information theory and perhaps even in other areas of physics, but we leave this for future work. We also state a conjecture regarding the monotonicity of the Renyi conditional mutual informations defined here with respect to the Renyi parameter $\alpha$. We prove that this conjecture is true in some special cases and when $\alpha$ is in a neighborhood of one.
TL;DR: In this article, the information terms due to the probability and current distributions are accounted for in the complementary Shannon and Fisher measures of the resultant information content of quantum states, and a generalization of the information-distance descriptors is also established.
Abstract: Several concepts of information theory (IT) are extended to cover the complex probability amplitudes (wave functions) of molecular quantum mechanics. The classical and non-classical aspects of the electronic structure are revealed by the electronic probability and phase distributions, respectively. The information terms due to the probability and current distributions are accounted for in the complementary Shannon and Fisher measures of the resultant information content of quantum states. Similar generalization of the information-distance descriptors is also established. The superposition principle (SP) of quantum mechanics, which introduces the conditional probabilities between quantum states, is used to generate a network of quantum communications in molecules, and to identify the non-additive contributions to physical and information quantities. The phase-relations in two-orbital model are explored. The orbital communication theory of the chemical bond introduces the entropic bond multiplicities and their partition into IT covalent/ionic components. The conditional probabilities between atomic orbitals, propagated via the network of the occupied molecular orbitals, which define the bond system and orbital communications in molecules, are generated from the bond-projected SP. In the one-determinantal representation of the molecular ground state the communication amplitudes are then related to elements of the charge and bond-order matrix. Molecular equilibria are reexamined and parallelism between the vertical (density-constrained) energy or entropy/information principles of IT and the corresponding thermodynamic criteria is emphasized.
TL;DR: In this article, a photon Hadamard gate was generated by observing the interference pattern created by the spatio-temporal overlap of photons emitted by two interfering electron paths and thus erased the electron-trajectory information.
Abstract: Coherent processing of quantum information and attosecond science have had so far little in common. We here show that recent data in high harmonic emission reveal a realization of a qubit and its coherent manipulation at the attosecond time scale. By observing the interference pattern created by the spatiotemporal overlap of photons emitted by two interfering electron paths we generate a photon Hadamard gate and thus erase the electron-trajectory information. This allows the measurement of the relative phase in electron-trajectory quantum superpositions which realize the qubit, opening the possibility for more elaborate schemes of coherent information processing within high-field physics.
TL;DR: In this article, the authors employ non-asymptotic classical information theory to show that one-way information reconciliation imposes fundamental limitations on the amount of secret key that can be extracted in the finite key regime.
Abstract: The security of quantum key distribution protocols is guaranteed by the laws of quantum mechanics. However, a precise analysis of the security properties requires tools from both classical cryptography and information theory. Here, we employ recent results in non-asymptotic classical information theory to show that one-way information reconciliation imposes fundamental limitations on the amount of secret key that can be extracted in the finite key regime. In particular, we find that an often used approximation for the information leakage during information reconciliation is not generally valid. We propose an improved approximation that takes into account finite key effects and numerically test it against codes for two probability distributions, that we call binary-binary and binary-Gaussian, that typically appear in quantum key distribution protocols.
TL;DR: In this paper, the entropic inequalities related to the quantum mutual information for bipartite systems and tomographic mutual information of two qubits in the Werner state were studied.
Abstract: We study the entropic inequalities related to the quantum mutual information for bipartite system and tomographic mutual information for the Werner state of two qubits. We discuss quantum correlations corresponding to the entanglement properties of the qubits in the Werner state.
TL;DR: In this paper, the authors exploit geometric properties of quantum states of light in optical cavities to carry out quantum non-demolition measurements and generalize the mode invisibility method to obtain information about the Wigner function of a squeezed coherent state in a non-destructive way.
Abstract: We exploit geometric properties of quantum states of light in optical cavities to carry out quantum non-demolition measurements. We generalize the 'mode invisibility' method to obtain information about the Wigner function of a squeezed coherent state in a non-destructive way. We also simplify the application of this non-demolition technique to measure single-photon and few-photon states.
Posted Content•
TL;DR: In this article, the standard relations between information theory and thermodynamics are challenged and the Szilard engine is revisited and the bound proposed by Landauer is replaced by a different one which includes errors in information processing.
Abstract: The standard relations between information theory and thermodynamics are challenged. The Szilard engine is revisited and the bound proposed by Landauer is replaced by a different one which includes errors in information processing. Instead of equivalence, complementarity of information and thermodynamical entropy is advocated. Finally, the relations between error correction and self-replication of states which can carry information are discussed.
TL;DR: Noise correlations between forward and backward paths in two-way quantum key distribution leads to reduced potentialities for an eavesdropper since she can only hide herself behind uncorrelated (natural) noise.
Abstract: We check for noise correlations between forward and backward paths in two-way quantum key distribution, which leads to reduced potentialities for an eavesdropper since she can only hide herself behind uncorrelated (natural) noise. The security enhancement is evaluated through the ratio of eavesdropper's information and legitimate users' information achievable against the most relevant individual attacks.
TL;DR: It is shown that it is not possible to attain a proper generalization of the quantum conditional mutual information by optimizing the distance in terms of quantum α-Renyi divergences over the set of all Markov states.
Abstract: We study the relation between the quantum conditional mutual information and the quantum $\alpha$-Renyi divergences. Considering the totally antisymmetric state we show that it is not possible to attain a proper generalization of the quantum conditional mutual information by optimizing the distance in terms of quantum $\alpha$-Renyi divergences over the set of all Markov states. The failure of the approach considered arises from the observation that a small quantum conditional mutual information does not imply that the state is close to a quantum Markov state.
TL;DR: In this article, the authors studied the one-shot zero-error classical capacity of a quantum channel assisted by quantum no-signalling correlations, and the reverse problem of exact simulation of a prescribed channel by a noiseless classical one.
Abstract: We study the one-shot zero-error classical capacity of a quantum channel assisted by quantum no-signalling correlations, and the reverse problem of exact simulation of a prescribed channel by a noiseless classical one. Quantum no-signalling correlations are viewed as two-input and two-output completely positive and trace preserving maps with linear constraints enforcing that the device cannot signal. Both problems lead to simple semidefinite programmes (SDPs) that depend only on the Kraus operator space of the channel. In particular, we show that the zero-error classical simulation cost is precisely the conditional min-entropy of the Choi-Jamiolkowski matrix of the given channel. The zero-error classical capacity is given by a similar-looking but different SDP; the asymptotic zero-error classical capacity is the regularization of this SDP, and in general we do not know of any simple form.
Interestingly however, for the class of classical-quantum channels, we show that the asymptotic capacity is given by a much simpler SDP, which coincides with a semidefinite generalization of the fractional packing number suggested earlier by Aram Harrow. This finally results in an operational interpretation of the celebrated Lovasz $\vartheta$ function of a graph as the zero-error classical capacity of the graph assisted by quantum no-signalling correlations, the first information theoretic interpretation of the Lovasz number.
TL;DR: In this paper, a general prescription is given for finding uncertainty relations that dictate the lower bounds on the measures of spread corresponding to two different representations of a partially coherent wave field or mixed quantum state, for a given measure of overall coherence or purity.
Abstract: A general prescription is given for finding uncertainty relations that dictate the lower bounds on the measures of spread corresponding to two different representations of a partially coherent wave field or mixed quantum state, for a given measure of overall coherence or purity. In particular it is shown that the coherent modes of the fields/states that achieve the lower bounds are independent of the measure of purity being used, and that this measure determines only the amount in which these modes contribute. Our results are important in the design of optical systems with partially coherent light and in quantum mixed states, for which maximal joint localization is desired. These ideas are illustrated for the case of optical beams, pulses propagating in dispersive media and quantum phase.
TL;DR: In this paper, it was shown that whenever the coherent information of a one-mode Gaussian channel is non-zero, its supremum is achieved for the infinite input power.
Abstract: We prove that whenever the coherent information of a one-mode Gaussian channel is non-zero its supremum is achieved for the infinite input power. This is a well established fact for the zero added classical noise, whereas the nonzero case has not been studied in detail. The presented analysis fills the gap for three canonical classes of one-mode Gaussian channels: the lossy, amplifying and additive classical noise channel class. For the remaining one-mode Gaussian channel classes the coherent information is known to vanish.
TL;DR: In this paper, the Schrodinger Equation and the Minkowski transformation are combined with the Canonical commutation relation to find an equivalence between the classical information in a quantum system and the integral of that system's energy and time in natural units.
Abstract: In the governing thought, I find an equivalence between the classical information in a quantum system and the integral of that system’s energy and time, specifically , in natural units. I solve this relationship in four ways: the first approach starts with the Schrodinger Equation and applies the Minkowski transformation; the second uses the Canonical commutation relation; the third through Gabor’s analysis of the time-frequency plane and Heisenberg’s uncertainty principle; and lastly by quantizing Brownian motion within the Bernoulli process and applying the Gaussian channel capacity. In support I give two examples of quantum systems that follow the governing thought: namely the Gaussian wave packet and the electron spin. I conclude with comments on the discretization of space and the information content of a degree of freedom.
TL;DR: In this article, a comprehensive approach that exceeds mere realism and antirealism to the field of quantum theories with informational foundations is presented, which is close to Husserl's explanation of the relationship between reality and the knowledge we have about it, and Bohr's personal explanation of quantum mechanics.
Abstract: Zeilinger-Brukner's informational foundations of quantum theory, a theory based on Zeilinger's foundational principle for quantum mechanics that an elementary system carried one bit of information, explains seemingly unintuitive quantum behavior with simple theoretical framework. It is based on the notion that distinction between reality and information cannot be made, therefore they are the same. As the critics of informational foundations of quantum theory show, this antirealistic move captures the theory in tautology, where information only refers to itself, while the relationships outside the information with the help of which the nature of information would be defined are lost and the questions "Whose information? Information about what?" cannot be answered. The critic's solution is a return to realism, where the observer's effects on the information are neglected. We show that radical antirealism of informational foundations of quantum theory is not necessary and that the return to realism is not the only way forward. A comprehensive approach that exceeds mere realism and antirealism is also possible: we can consider both sources of the constraints on the information, those coming from the observer and those coming from the observed system/nature/reality. The information is always the observer's information about the observed. Such a comprehensive philosophical approach can still support the theoretical framework of informational foundations of quantum theory: If we take that one bit is the smallest amount of information in the form of which the observed reality can be grasped by the observer, we can say that an elementary system (grasped and defined as such by the observer) correlates to one bit of information. Our approach thus explains all the features of the quantum behavior explained by informational foundations of quantum theory: the wave function and its collapse, entanglement, complementarity and quantum randomness. However, it does so in a more comprehensive and intuitive way. The presented approach is close to Husserl's explanation of the relationship between reality and the knowledge we have about it, and to Bohr's personal explanation of quantum mechanics, the complexity of which has often been missed and simplified to mere antirealism. Our approach thus reconnects phenomenology with contemporary philosophy of science and introduces the comprehensive approach that exceeds mere realism and antirealism to the field of quantum theories with informational foundations, where such an approach has not been taken before. Quanta 2014; 3: 32–42.
TL;DR: In this article, it was shown that for every qubit of quantum information, there is a well-defined notion of "the amount of energy that carries it", because it is a conserved quantity.
Abstract: We show that for every qubit of quantum information, there is a well-defined notion of "the amount of energy that carries it", because it is a conserved quantity. This generalizes to larger systems and any conserved quantites: the eigenvalue spectrum of conserved charges has to be preserved while transferring quantum information. It is possible to "apparently" violate these conservations by losing a small fraction of information, but that must invoke a specific process which requires a large scale coherence. We discuss its implication regarding the black hole information paradox.
TL;DR: In this paper, it was shown that the von Neumann-Lueders collapse rules in quantum mechanics always select the unique state that maximises the quantum relative entropy with respect to the premeasurement state, subject to the constraint that the postmeasurements state has to be compatible with the knowledge gained in the measurement.
Abstract: We show that the von Neumann--Lueders collapse rules in quantum mechanics always select the unique state that maximises the quantum relative entropy with respect to the premeasurement state, subject to the constraint that the postmeasurement state has to be compatible with the knowledge gained in the measurement. This way we provide an information theoretic characterisation of quantum collapse rules by means of the maximum relative entropy principle.
04 Dec 2014
TL;DR: This work outlines how optimality can be achieved by using a small quantum computer, building on recent proposals for optimal qubit state discrimination with multiple copies.
Abstract: The ability to distinguish between coherent states optimally plays in important role in the efficient usage of quantum resources for classical communication and sensing applications. While it has been known since the early 1970’s how to optimally distinguish between two coherent states, generalizations to larger sets of coherent states have so far failed to reach optimality. In this work we outline how optimality can be achieved by using a small quantum computer, building on recent proposals for optimal qubit state discrimination with multiple copies.
TL;DR: In this paper, a five-party scheme for sharing a single-qutrit state by using GHZ states as the quantum channel is presented and demonstrates a high degree of symmetry and provides a useful inspiration for implementing hierarchical quantum information.
Abstract: In this paper, we first present a five-party scheme for sharing a single-qutrit state by using GHZ states as the quantum channel. Any one of the agents has the access to reconstruct the original state if other controlling agents cooperate with him. We also sketch the generation of five-party scheme to the case of multi-qudit states and multiple participants by a composite channel composed of generalized Bell states and GHZ states. In our scheme, the physical operations, especially for the controllers and the final receiver, are considerably reduced. It also demonstrates a high degree of symmetry and provides a useful inspiration for implementing hierarchical quantum information splitting.
Posted Content•
TL;DR: A quantum version of Belief Propagation(BP) Algorithm is used to integrate the distributed information, which is in the form of density matrix, which can be approximated to local structures to increase the accuracy of QBP.
Abstract: Quantum systems are the future candidates for computers and information processing devices. Information about quantum states and processes may be incomplete and scattered in these systems. We use a quantum version of Belief Propagation(BP) Algorithm to integrate the distributed information. In this algorithm the distributed information, which is in the form of density matrix, can be approximated to local structures. The validity of this algorithm is measured in comparison with Suzuki-Trotter(ST) method, using simulated information. ST in 3-body Heisenberg example gives a more accurate answer, however Quantum Belief Propagation (QBP) runs faster based on complexity. In order to develop it in the future, we should be looking for ways to increase the accuracy of QBP.
Patent•
19 Feb 2014
TL;DR: In this article, a self-adaption apodization method based on phase coherent information is proposed, which includes the steps of conducting Hilbert change on all routes of channel signals to obtain the phase information, obtaining a dynamic weighting value of each channel, and conducting beam forming at last.
Abstract: The invention provides a self-adaption apodization method based on phase coherent information. The method includes the steps of conducting Hilbert change on all routes of channel signals to obtain the phase information, obtaining a dynamic weighting value of each channel through a certain self-adaption processing method according to preliminary phase estimation and the deviation of the phase information of each channel, and conducting beam forming at last. To improve the robustness of the self-adaption processing method, a phase variance sensitive threshold and multiple geometrical mapping relation curves between a phase difference and the weighting values are introduced into the calculation process of the dynamic weighting values. According to the self-adaption apodization method, by means of internal phase diversities, received in the beam forming process, of data of the multiple channels, side lobe signals and grating lobe signals are restrained, meanwhile, the width of a main beam is reduced, and transverse resolving ability of images is improved.