Coherent information

About: Coherent information is a research topic. Over the lifetime, 1225 publications have been published within this topic receiving 46672 citations.

How a Quantum Theory Based on Generalized Coherent States Resolves the EPR and Measurement Problems

Abstract: It is shown that the quantum theory can be formulated on homogeneous spaces of generalized coherent states in a manner that accounts for interference, entanglement, and the linearity of dynamics without using the superposition principle. The coherent state labels, which are essentially instructions for preparing states, make it unnecessary to identify properties with projectors in Hilbert space. This eliminates the so called "eigenvalue-eigenstate" link, and the theory thereby escapes the measurement problem. What the theory allows us to predict is the distribution in the outcomes of tests of relations between coherent states. It is shown that quantum non-determinism can be attributed to a hidden variable (noise) in the space of relations without violating the no-go theorems (e.g. Kochen-Specker). It is shown that the coherent state vacuum is distorted when entangled states are generated. The non-locality of the vacuum permits this distortion to be felt everywhere without the transmission of a signal and thereby accounts for EPR correlations in a manifestly covariant way.

Byuons, Quantum Information Channel, Consciousness and Universe

Abstract: The physics of consciousness and universal mind is shown on the base of theory of byuons, the theory of “life’ of special unobservable discrete objects—byuons from which the surrounding space and the world of elementary particles are formed. An essential distinction of that theory from the modern models in the classical and quantum field theories is that the potentials of physical fields (gravitational, electromagnetic, asf.) gain exactly fixable, measurable values. Basic axioms and some conclusions of this theory are discussed. The theory of byuons predicts the existence of a new force and a new quantum information channel in nature. All objects of the Universe are shown to be united into the unique information field due to the huge interval of uncertainty in the coordinate (Δx = L = 1028 cm) of objects 4b (object formed during four-contact byuon-byuon interaction ( mc24b = 33 eV)) forming the surrounding physical space. It is a new quantum information channel.

Motion-based prediction is sufficient to solve the aperture problem

Abstract: In low-level sensory systems, it is still unclear how the noisy information collected locally by neurons may give rise to a coherent global percept. This is well demonstrated for the detection of motion in the aperture problem: as luminance of an elongated line is symmetrical along its axis, tangential velocity is ambiguous when measured locally. Here, we develop the hypothesis that motion-based predictive coding is sufficient to infer global motion. Our implementation is based on a context-dependent diffusion of a probabilistic representation of motion. We observe in simulations a progressive solution to the aperture problem similar to physio-logy and behavior. We demonstrate that this solution is the result of two underlying mechanisms. First, we demonstrate the formation of a tracking behavior favoring temporally coherent features independent of their texture. Second, we observe that incoherent features are explained away, while coherent information diffuses progressively to the global scale. Most previous models included ad hoc mechanisms such as end-stopped cells or a selection layer to track specific luminance-based features as necessary conditions to solve the aperture problem. Here, we have proved that motion-based predictive coding, as it is implemented in this functional model, is sufficient to solve the aperture problem. This solution may give insights into the role of prediction underlying a large class of sensory computations.

Effects of imperfect noise correlations on decoherence-free subsystems: SU(2) diffusion model

Abstract: We present a model of an $N$-qubit channel where consecutive qubits experience correlated random rotations Our model is an extension to the standard decoherence-free subsystems approach which assumes that all qubits experience the same disturbance The variation of rotations acting on consecutive qubits is modeled as diffusion on the SU(2) group The model may be applied to spins traveling in a varying magnetic field or to photons passing through a fiber whose birefringence fluctuates over the time separation between photons We derive an explicit formula describing the action of the channel on an arbitrary $N$-qubit state For $N=3$ we investigate the effects of diffusion on both the classical and quantum capacities of the channel We observe that nonorthogonal states are necessary to achieve optimal classical capacity Furthermore, we find the threshold for the diffusion parameter above which coherent information of the channel vanishes

Bounds on the entropy generated when timing information is extracted from microscopic systems

Abstract: We consider Hamiltonian quantum systems with energy bandwidth \Delta E and show that each measurement that determines the time up to an error \Delta t generates at least the entropy (\hbar/(\Delta t \Delta E))^2/2. Our result describes quantitatively to what extent all timing information is quantum information in systems with limited energy. It provides a lower bound on the dissipated energy when timing information of microscopic systems is converted to classical information. This is relevant for low power computation since it shows the amount of heat generated whenever a band limited signal controls a classical bit switch. Our result provides a general bound on the information-disturbance trade-off for von-Neumann measurements that distinguish states on the orbits of continuous unitary one-parameter groups with bounded spectrum. In contrast, information gain without disturbance is possible for some completely positive semi-groups. This shows that readout of timing information can be possible without entropy generation if the autonomous dynamical evolution of the clock is dissipative itself.