16,846 research outputs found

    Blowup of Jang's equation at outermost marginally trapped surfaces

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    The aim of this paper is to collect some facts about the blowup of Jang's equation. First, we discuss how to construct solutions that blow up at an outermost MOTS. Second, we exclude the possibility that there are extra blowup surfaces in data sets with non-positive mean curvature. Then we investigate the rate of convergence of the blowup to a cylinder near a strictly stable MOTS and show exponential convergence near a strictly stable MOTS.Comment: 15 pages. This revision corrects some typo

    Non-adiabatic holonomic quantum computation

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    We develop a non-adiabatic generalization of holonomic quantum computation in which high-speed universal quantum gates can be realized by using non-Abelian geometric phases. We show how a set of non-adiabatic holonomic one- and two-qubit gates can be implemented by utilizing optical transitions in a generic three-level Λ\Lambda configuration. Our scheme opens up for universal holonomic quantum computation on qubits characterized by short coherence times.Comment: Some changes, journal reference adde

    Bounds on area and charge for marginally trapped surfaces with cosmological constant

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    We sharpen the known inequalities AΛ4π(1g)A \Lambda \le 4\pi (1-g) and A4πQ2A\ge 4\pi Q^2 between the area AA and the electric charge QQ of a stable marginally outer trapped surface (MOTS) of genus g in the presence of a cosmological constant Λ\Lambda. In particular, instead of requiring stability we include the principal eigenvalue λ\lambda of the stability operator. For Λ=Λ+λ>0\Lambda^{*} = \Lambda + \lambda > 0 we obtain a lower and an upper bound for ΛA \Lambda^{*} A in terms of ΛQ2 \Lambda^{*} Q^2 as well as the upper bound Q1/(2Λ) Q \le 1/(2\sqrt{\Lambda^{*}}) for the charge, which reduces to Q1/(2Λ) Q \le 1/(2\sqrt{\Lambda}) in the stable case λ0\lambda \ge 0. For Λ<0\Lambda^{*} < 0 there remains only a lower bound on AA. In the spherically symmetric, static, stable case one of the area inequalities is saturated iff the surface gravity vanishes. We also discuss implications of our inequalities for "jumps" and mergers of charged MOTS.Comment: minor corrections to previous version and to published versio

    Delocalization power of global unitary operations on quantum information

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    We investigate how originally localized two pieces of quantum information represented by a tensor product of two unknown qudit states are delocalized by performing two-qudit global unitary operations. To characterize the delocalization power of global unitary operations on quantum information, we analyze the necessary and sufficient condition to deterministically relocalize one of the two pieces of quantum information to its original Hilbert space by using only LOCC. We prove that this LOCC one-piece relocalization is possible if and only if the global unitary operation is local unitary equivalent to a controlled-unitary operation. The delocalization power and the entangling power characterize different non-local properties of global unitary operations.Comment: 14 pages, 1 figur

    Minimum-error discrimination between symmetric mixed quantum states

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    We provide a solution of finding optimal measurement strategy for distinguishing between symmetric mixed quantum states. It is assumed that the matrix elements of at least one of the symmetric quantum states are all real and nonnegative in the basis of the eigenstates of the symmetry operator.Comment: 10 page

    High-Order Contamination in the Tail of Gravitational Collapse

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    It is well known that the late-time behaviour of gravitational collapse is {\it dominated} by an inverse power-law decaying tail. We calculate {\it higher-order corrections} to this power-law behaviour in a spherically symmetric gravitational collapse. The dominant ``contamination'' is shown to die off at late times as M2t4ln(t/M)M^2t^{-4}\ln(t/M). This decay rate is much {\it slower} than has been considered so far. It implies, for instance, that an `exact' (numerical) determination of the power index to within 1\sim 1 % requires extremely long integration times of order 104M10^4 M. We show that the leading order fingerprint of the black-hole electric {\it charge} is of order Q2t4Q^2t^{-4}.Comment: 12 pages, 2 figure

    Transverse nucleon structure and diagnostics of hard parton-parton processes at LHC

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    We propose a new method to determine at what transverse momenta particle production in high-energy pp collisions is governed by hard parton-parton processes. Using information on the transverse spatial distribution of partons obtained from hard exclusive processes in ep/gamma p scattering, we evaluate the impact parameter distribution of pp collisions with a hard parton-parton process as a function of p_T of the produced parton (jet). We find that the average pp impact parameters in such events depend very weakly on p_T in the range 2 < p_T < few 100 GeV, while they are much smaller than those in minimum-bias inelastic collisions. The impact parameters in turn govern the observable transverse multiplicity in such events (in the direction perpendicular to the trigger particle or jet). Measuring the transverse multiplicity as a function of p_T thus provides an effective tool for determining the minimum p_T for which a given trigger particle originates from a hard parton-parton process. Additional tests of the proposed geometric correlations are possible by measuring the dependence on the trigger rapidity. Various strategies for implementing this method are outlined.Comment: 9 pages, 6 figure

    Multi Mode Interferometer for Guided Matter Waves

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    We describe the fundamental features of an interferometer for guided matter waves based on Y-beam splitters and show that, in a quasi two-dimensional regime, such a device exhibits high contrast fringes even in a multi mode regime and fed from a thermal source.Comment: Final version (accepted to PRL

    Density functional theory for freezing transition of vortex-line liquid with periodic layer pinning

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    By the density functional theory for crystallization, it is shown that for vortex lines in an underlying layered structure a smectic phase with period m=2 can be stabilized by strong layer pinning. The freezing of vortex liquid is then two-step, a second-order liquid-smectic transition and a first-order smectic-lattice transition. DFT also indicates that a direct, first-order liquid-lattice transition preempts the smectic order with m>2 irrespectively of the pinning strength. Possible H-T phase diagrams are mapped out. Implications of the DFT results to the interlayer Josephson vortex system in high-Tc cuprates are given.Comment: 4 pages, 5 figures, references adde
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