1,237 research outputs found

    On the Machian Origin of Inertia

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    We examine Sciama's inertia theory: we generalise it, by combining rotation and expansion in one unique model, we find the angular speed of the Universe, and we stress that the theory is zero-total-energy valued. We compare with other theories of the same null energy background. We determine the numerical value of a constant which appears in the Machian inertial force expression devised by Graneau and Graneau[2], by introducing the above angular speed. We point out that this last theory is not restricted to Newtonian physics as those authors stated but is, in fact, compatible with other cosmological and gravitational theories. An argument by Berry[7] is shown in order to "derive" Brans-Dicke relation in the present context.Comment: 10 pages including front one. New version was accepted to publication by Astrophysics and Space Scienc

    Relations for classical communication capacity and entanglement capability of two-qubit operations

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    Bipartite operations underpin both classical communication and entanglement generation. Using a superposition of classical messages, we show that the capacity of a two-qubit operation for error-free entanglement-assisted bidirectional classical communication can not exceed twice the entanglement capability. In addition we show that any bipartite two-qubit operation can increase the communication that may be performed using an ensemble by twice the entanglement capability.Comment: 4 page

    Periodization for the Multi-Sport Athlete

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    CALGreen: California Green Building Standards Code: Blog 3

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    CALGreen encourages local governments to go beyond statewide Energy Code regulations to achieve greater building energy efficiency and cost savings, all while providing the necessary resources to do so. The currently enforced version of CALGreen is the 2019 CALGreen code. Mandates and voluntary provisions in the 2022 CALGreen update will go into effect January 1, 2023.¹ If both the 2022 Energy Code and 2022 CALGreen mandatory and voluntary standards were to be adopted statewide, the carbon reductions would be equivalent to removing 8,000 fuel-powered cars off the road for the first year and 24,000 fuel-powered cars by the third year.² This means that 2022 is a critical year for local jurisdictions throughout California and the San Diego region to inform, educate, and implement opportunities that maximize energy savings, greenhouse gas emission reductions, and public health benefits.https://digital.sandiego.edu/npi-sdclimate/1019/thumbnail.jp

    Misleading signatures of quantum chaos

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    The main signature of chaos in a quantum system is provided by spectral statistical analysis of the nearest neighbor spacing distribution and the spectral rigidity given by Δ3(L)\Delta_3(L). It is shown that some standard unfolding procedures, like local unfolding and Gaussian broadening, lead to a spurious increase of the spectral rigidity that spoils the Δ3(L)\Delta_3(L) relationship with the regular or chaotic motion of the system. This effect can also be misinterpreted as Berry's saturation.Comment: 4 pages, 5 figures, submitted to Physical Review

    Resonances and the thermonuclear reaction rate

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    We present an approximate analytic expression for thermonuclear reaction rate of charged particles when the cross section contains a single narrow or wide resonance described by a Breit-Wigner shape. The resulting expression is uniformly valid as the effective energy and resonance energy coalesce. We use our expressions to calculate the reaction rate for 12^{12}C(p,γ\gamma)13^{13}N.Comment: 4 pages, 1 figure, presented at the VIII International Conference on Nucleus-Nucleus in Moscow (Russia) on June 17-21, 200

    General Adiabatic Evolution with a Gap Condition

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    We consider the adiabatic regime of two parameters evolution semigroups generated by linear operators that are analytic in time and satisfy the following gap condition for all times: the spectrum of the generator consists in finitely many isolated eigenvalues of finite algebraic multiplicity, away from the rest of the spectrum. The restriction of the generator to the spectral subspace corresponding to the distinguished eigenvalues is not assumed to be diagonalizable. The presence of eigenilpotents in the spectral decomposition of the generator forbids the evolution to follow the instantaneous eigenprojectors of the generator in the adiabatic limit. Making use of superadiabatic renormalization, we construct a different set of time-dependent projectors, close to the instantaneous eigeprojectors of the generator in the adiabatic limit, and an approximation of the evolution semigroup which intertwines exactly between the values of these projectors at the initial and final times. Hence, the evolution semigroup follows the constructed set of projectors in the adiabatic regime, modulo error terms we control

    Entangling power and operator entanglement in qudit systems

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    We establish the entangling power of a unitary operator on a general finite-dimensional bipartite quantum system with and without ancillas, and give relations between the entangling power based on the von Neumann entropy and the entangling power based on the linear entropy. Significantly, we demonstrate that the entangling power of a general controlled unitary operator acting on two equal-dimensional qudits is proportional to the corresponding operator entanglement if linear entropy is adopted as the quantity representing the degree of entanglement. We discuss the entangling power and operator entanglement of three representative quantum gates on qudits: the SUM, double SUM, and SWAP gates.Comment: 8 pages, 1 figure. Version 3: Figure was improved and the MS was a bit shortene

    Perturbative Formulation and Non-adiabatic Corrections in Adiabatic Quantum Computing Schemes

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    Adiabatic limit is the presumption of the adiabatic geometric quantum computation and of the adiabatic quantum algorithm. But in reality, the variation speed of the Hamiltonian is finite. Here we develop a general formulation of adiabatic quantum computing, which accurately describes the evolution of the quantum state in a perturbative way, in which the adiabatic limit is the zeroth-order approximation. As an application of this formulation, non-adiabatic correction or error is estimated for several physical implementations of the adiabatic geometric gates. A quantum computing process consisting of many adiabatic gate operations is considered, for which the total non-adiabatic error is found to be about the sum of those of all the gates. This is a useful constraint on the computational power. The formalism is also briefly applied to the adiabatic quantum algorithm.Comment: 5 pages, revtex. some references adde
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