Quantum Shannon theory with superpositions of trajectories Chiribella, Giulio; Kristjánsson, Hlér
Proceedings of the Royal Society. A, Mathematical, physical, and engineering sciences,
05/2019, Volume:
475, Issue:
2225
Journal Article
Peer reviewed
Open access
Shannon's theory of information was built on the assumption that the information carriers were classical systems. Its quantum counterpart, quantum Shannon theory, explores the new possibilities ...arising when the information carriers are quantum systems. Traditionally, quantum Shannon theory has focused on scenarios where the internal state of the information carriers is quantum, while their trajectory is classical. Here we propose a second level of quantization where both the information and its propagation in space-time is treated quantum mechanically. The framework is illustrated with a number of examples, showcasing some of the counterintuitive phenomena taking place when information travels simultaneously through multiple transmission lines.
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Long-term creep properties and the effect of water are important for fiber reinforced polymer (FRP) composite materials used in offshore applications. Epoxies are often used as a matrix material in ...such composites. A typical design lifetime of offshore FRP structures is 25 or more years in direct contact with water leading to some deterioration of the material properties. Knowing and predicting the extent of the material property deterioration in water is of great interest for designers and users of the offshore FRP structures. It has been established that the time-temperature superposition principle (TTSP) is a useful tool for estimating changes in properties of polymer materials at long times or extreme temperatures. In this work, a time-temperature-plasticization superposition principle (TTPSP) is described and used for predicting the long-term creep behavior of an epoxy compound. The studied epoxy does not degrade chemically via hydrolysis or chain scission but is negatively affected by plasticization with water. The methodology enables prediction of the long-term viscoelastic behavior of amorphous polymers at temperatures below the glass transition (
) using short-term creep experimental data. The results also indicate that it is possible to estimate the creep behavior of the plasticized polymer based on the short-term creep data of the respective dry material and the difference between
values of dry polymer and plasticized polymer. The methodology is useful for accelerated testing and for predicting the time-dependent mechanical properties of a plasticized polymer below the glass transition temperature.
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Whether quantum physics is universally valid is an open question with far-reaching implications. Intense research is therefore invested into testing the quantum superposition principle with ever ...heavier and more complex objects. Here we propose a radically new, experimentally viable route towards studies at the quantum-to-classical borderline by probing the orientational quantum revivals of a nanoscale rigid rotor. The proposed interference experiment testifies a macroscopic superposition of all possible orientations. It requires no diffraction grating, uses only a single levitated particle, and works with moderate motional temperatures under realistic environmental conditions. The first exploitation of quantum rotations of a massive object opens the door to new tests of quantum physics with submicron particles and to quantum gyroscopic torque sensors, holding the potential to improve state-of-the-art devices by many orders of magnitude.
SignificanceDynamic bonds have been found to enhance fracture toughness of hydrogels as sacrificial bonds, but the role of dynamic bonds to fatigue threshold of hydrogels is poorly understood because ...the wide dynamic range of viscoelastic response imposes a challenge on fatigue experiments. Here, by using polyampholyte hydrogels, we adopted a time-salt superposition principle to access a wide range of time scales that are otherwise difficult to access in fatigue tests. Relations between fatigue threshold and strain rate in elastic and viscoelastic regimes and the corresponding mechanism correlated to permanent/dynamic bonds were revealed. We believe that this work gives important insight into the design and development of fatigue-resistant soft materials composed of dynamic bonds.
A few decades ago, quantum optics stood out as a new domain of physics by exhibiting states of light with no classical equivalent. The first investigations concerned single photons, squeezed states, ...twin beams, and Einstein-Podolsky-Rosen states, which involve only one or two modes of the electromagnetic field. The study of the properties of quantum light then evolved in the direction of more and more complex and rich situations, involving many modes of the spatial, temporal, frequency, or polarization type. Actually, each mode of the electromagnetic field can be considered as an individual quantum degree of freedom. It is then possible, using the techniques of nonlinear optics, to couple different modes and thus build in a controlled way a quantum network H. Jeff Kimble, Nature (London) 453, 1023 (2008) in which the nodes are optical modes, and that is endowed with a strong multipartite entanglement. In addition, such networks can be easily reconfigurable and are subject only to weak decoherence. They indeed open many promising perspectives for optical communications and computation. Because of the linearity of Maxwell equations a linear superposition of two modes is another mode. This means that a "modal superposition principle" exists hand in hand with the regular quantum state superposition principle. The purpose of this review is to show the interest of considering these two aspects of multimode quantum light in a global way. Indeed, using different sets of modes allows one to consider the same quantum state under different perspectives: a given state can be entangled in one basis and factorized in another. It is shown that there exist some properties that are invariant over a change in the choice of the basis of modes. The method of finding the minimal set of modes that are needed to describe a given multimode quantum state is also presented. It is then shown how to produce, characterize, tailor, and use multimode quantum light while also considering the effect of loss and amplification on such light and the modal aspects of the two-photon coincidences. Switching to applications to quantum technologies, this review shows that it is possible to find not only quantum states that are likely to improve parameter estimation but also the optimal modes in which these states "live." Finally, details on how to use such quantum modal networks for measurement-based quantum computation are presented.
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Crystallographic texture in metals influences material properties, e.g., r-value. In this work, a moderately strong texture is obtained in AA5182-O through continuous-bending-under-tension processing ...followed by a recovery heat treatment from the initial weak cube texture. EBSD scans confirm that the texture is retained after heat treating. The processed material exhibits increased strength and reduced planar anisotropy, providing benefits to subsequent forming operations, compared to the as-received material. Crystal plasticity simulations confirm the texture change during deformation and predict the flow stress response. Such simulations can be used for stress superposition process design to intentionally manipulate material properties.
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The ability of the internal states of a working fluid to be in a coherent superposition is one of the basic properties of a quantum heat engine. It was recently predicted that in the regime of small ...engine action, this ability can enable a quantum heat engine to produce more power than any equivalent classical heat engine. It was also predicted that in the same regime, the presence of such internal coherence causes different types of quantum heat engines to become thermodynamically equivalent. Here, we use an ensemble of nitrogen vacancy centers in diamond for implementing two types of quantum heat engines, and experimentally observe both effects.
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Synthesis and analysis of suspension-embedded energy harvesters using quarter-car model is inefficient and skews the performance results of the harvesters. The preliminary analysis showed that only a ...small amount of vibration energy can be recovered. The quarter-car model does not allow inclusion of both the pitch and heave effects leading to underestimation of the harvesters' power generation. A 2-D suspension system is explored to capture the dynamics between the front and back wheels of the car as well as the variation in the road profile. A Go-Kart vehicle is used here to validate the model used to represent the harvesters’ dynamics and energy conversion capability. The vehicle was retrofitted with a front-mounted energy harvester built in our lab to assess the efficiency of the harvester to generate energy from speed bumps. The generated electrical power transmissibility index is used as the main objective function and constrained by a minimal ride comfort efficiency index. During the optimization process, a critical threshold ride comfort level is guaranteed through the use of a penalty factor in the objective function. The harvesters are able to recover significant amount of energy and maintain a reasonable comfort level.
•Obtain energy harvest and traffic safety.•Capture dynamics on car's front and back wheels.•Use power transmissibility and ride comfort index.
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•Futility of the Fuoss-Kirkwood relation proven by impedance parity with reason outlined.•Complex-valued distribution of relaxation times (DRT) using the Hilbert integral transform.•Inversion of DRT ...impedance by Mellin integral transform possible.
The Fuoss-Kirkwood (FK) relation is used to derive analytical expressions for the distribution of uncorrelated relaxation times (DRT), particularly of probed biochemical and electrochemical systems, often without scrutiny. Its futility is proven simply by using the parity of impedance with complex frequencies. However, given the futile nature of the FK relation, these expressions are not suitable for validation of computed DRT spectra. Despite this, the need for such expressions persists. Addressing this need and the oversight of the dependency of the DRT value on the underlying data, the DRT is extended into the complex plane using the Hilbert transform (HT). It makes the DRT universal for any complex-valued quantity to not only quantify the extent of relaxations but also to assess their nature. keyword: distribution; integral transforms; relaxation time; superposition.
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A fundamental approach for the characterization and quantification of all kinds of resources is to study the conversion between different resource objects under certain constraints. Here we analyze, ...from a resource-nonspecific standpoint, the optimal efficiency of resource formation and distillation tasks with only a single copy of the given quantum state, thereby establishing a unified framework of one-shot quantum resource manipulation. We find general bounds on the optimal rates characterized by resource measures based on the smooth max- or min-relative entropies and hypothesis testing relative entropy, as well as the free robustness measure, providing them with general operational meanings in terms of optimal state conversion. Our results encompass a wide class of resource theories via the theory-dependent coefficients we introduce, and the discussions are solidified by important examples, such as entanglement, coherence, superposition, magic states, asymmetry, and thermal nonequilibrium.
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