Seismic reflection profiles across the Hikurangi Plateau Large Igneous Province and adjacent margins reveal the faulted volcanic basement and overlying Mesozoic‐Cenozoic sedimentary units as well as the structure of the paleoconvergent Gondwana margin at the southern plateau limit. The Hikurangi Plateau crust can be traced 50–100 km southward beneath the Chatham Rise where subduction cessation timing and geometry are interpreted to be variable along the margin. A model fit of the Hikurangi Plateau back against the Manihiki Plateau aligns the Manihiki Scarp with the eastern margin of the Rekohu Embayment. Extensional and rotated block faults which formed during the breakup of the combined Manihiki‐Hikurangi plateau are interpreted in seismic sections of the Hikurangi Plateau basement. Guyots and ridge‐like seamounts which are widely scattered across the Hikurangi Plateau are interpreted to have formed at 99–89 Ma immediately following Hikurangi Plateau jamming of the Gondwana convergent margin at ∼100 Ma. Volcanism from this period cannot be separately resolved in the seismic reflection data from basement volcanism; hence seamount formation during Manihiki‐Hikurangi Plateau emplacement and breakup (125–120 Ma) cannot be ruled out. Seismic reflection data and gravity modeling suggest the 20‐Ma‐old Hikurangi Plateau choked the Cretaceous Gondwana convergent margin within 5 Ma of entry. Subsequent uplift of the Chatham Rise and slab detachment has led to the deposition of a Mesozoic sedimentary unit that thins from ∼1 km thickness northward across the plateau. The contrast with the present Hikurangi Plateau subduction beneath North Island, New Zealand, suggests a possible buoyancy cutoff range for LIP subduction consistent with earlier modeling.

It is not a problem to complement a classical bit, i.e. to change the value of a bit, a 0 to a 1 and vice versa. This is accomplished by a NOT gate. Complementing a qubit in an unknown state, however, is another matter. We show that this operation cannot be done perfectly. We define the Universal-NOT (U-NOT) gate which out of N identically prepared pure input qubits generates M output qubits in a state which is as close as possible to the perfect complement. This gate can be realized by classical estimation and subsequent re-preparation of complements of the estimated state. Its fidelity is therefore equal to the fidelity F = (N + 1)/(N + 2) of optimal estimation, and does not depend on the required number of outputs. We also show that when some additional a priori information about the state of input qubit is available, than the fidelity of the quantum NOT gate can be much better than the fidelity of estimation. PACS number: 03.65.Bz, 03.67.-a There was an odd qubit from Donegal, who wanted to become most orthogonal.He went through a gate, but not very straight, and came out instead as a Buckyball.Classical information consists of bits, each of which can be either 0 or 1. Quantum information, on the other hand, consists of qubits which are two-level quantum systems with one level labeled |0 and the other |1 . Qubits can not only be in one of the two levels, but in any superposition of them as well. This fact makes the properties of quantum information quite different from those of its classical counterpart. For example, it is not possible to construct a device which will perfectly copy an arbitrary qubit [1,2] while the copying of classical information presents no difficulties. Another difference between classical and quantum information is as follows: It is not a problem to complement a classical bit, i.e. to change the value of a bit, a 0 to a 1 and vice versa. This is accomplished by a NOT gate. Complementing a qubit, however, is another matter. The complement of a qubit |Ψ is the qubit |Ψ ⊥ which is orthogonal to it. Is it possible to build a device which will take an arbitrary (unknown) qubit and transform it into the qubit orthogonal to it?The best intuition for this problem is obtained by looking at the desired operation as an operation on the Poincaré sphere, which represents the set of pure states of a qubit system. Thus every state, pure or mixed, is represented by a vector in a three-dimensional space, whose components are the expectations of the three Pauli matrices. The full state space is thereby mapped onto the unit ball, whose surface represents the set of pure states. In this picture the ambiguity of choosing an overall phase for |Ψ is already eliminated. The points corresponding to |Ψ and |Ψ ⊥ are antipodes of each other. The desired Universal-NOT (U-NOT) operation is therefore nothing but the inversion of the Poincaré sphere.Note that the inversion preserves angles (related in a simple way to the scalar product | Φ, Ψ | of rays), so by Wigner's Theorem the ideal U-NOT must be implemented eith...

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We present the results of volcanological, geochemical, and geochronological studies of volcanic rocks from Malpelo Island on the Nazca plate (15.8-17.3 Ma) belonging to the Galápagos hotspot tracks, and igneous complexes (20.8-71.3 Ma) along the Pacific margin of Costa Rica and Panama. The igneous complexes consist of accreted portions of ocean island and seamount volcanoes and aseismic ridges, representing the missing (primarily subducted) history of the Galápagos hotspot. The age and geochemical data directly link the Galápagos hotspot tracks on the Pacific Ocean floor to the Caribbean large igneous province (ca. 72-95 Ma), confirming a Pacific origin for the Caribbean oceanic plateau from the Galápagos hotspot. We propose that emplacement of this oceanic plateau between the Americas and interaction of the Galápagos hotspot tracks with the Central American Arc played a fundamental role in the formation of land bridges between the Americas in Late Cretaceous-Paleocene and Pliocene-Holocene time. The land bridges allowed the exchange of terrestrial faunas (e.g., dinosaurs, mastodons, saber-tooth cats, and ground sloths) between the Americas and served as barriers for the exchange of marine organisms between the central Pacific Ocean and the Caribbean Sea and the central Atlantic Ocean.

[1] Alternative reconstructions of the Jurassic northern extent of Greater India differ by up to several thousand kilometers. We present a new model that is constrained by revised seafloor spreading anomalies, fracture zones and crustal ages based on drillsites/dredges from all the abyssal plains along the West Australian margin and the Wharton Basin, where an unexpected sliver of Jurassic seafloor (153 Ma) has been found embedded in Cretaceous (95 My old) seafloor. Based on fracture zone trajectories, this NeoTethyan sliver must have originally formed along a western extension of the spreading center that formed the Argo Abyssal Plain, separating a western extension of West Argoland/West Burma from Greater India as a ribbon terrane. The NeoTethyan sliver, Zenith and Wallaby plateaus moved as part of Greater India until westward ridge jumps isolated them. Following another spreading reorganization, the Jurassic crust resumed migrating with Greater India until it was re-attached to the Australian plate $95 Ma. The new Wharton Basin data and kinematic model place strong constraints on the disputed northern Jurassic extent of Greater India. Late Jurassic seafloor spreading must have reached south to the Cuvier Abyssal Plain on the West Australian margin, connected to a spreading ridge wrapping around northern Greater India, but this Jurassic crust is no longer preserved there, having been entirely transferred to the conjugate plate by ridge propagations. This discovery constrains the major portion of Greater India to have been located south of the large-offset WallabyZenith Fracture Zone, excluding much larger previously proposed shapes of Greater India.

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Surprisingly, there is little evidence for the involvement of North Atlantic N-MORB source mantle, as would be expected from the interaction of the Iceland plume and the surrounding asthenosphere in form of plume-ridge interaction. The preferential sampling of the enriched and depleted components in the off-rift and main rift systems, respectively, can be explained by differences in the geometry of the melting regions. In the off-rift areas, melting columns are truncated deeper and thus are shorter, which leads to preferential melting of the enriched component, as this starts melting deeper than the depleted component. In contrast, melting proceeds to shallower depths beneath the main rifts. The longer melting columns also produce significant amounts of melt from the more refractory (lower crustal/lithospheric) component.

We report on the experimental realization of electric quantum walks, which mimic the effect of an electric field on a charged particle in a lattice. Starting from a textbook implementation of discrete-time quantum walks, we introduce an extra operation in each step to implement the effect of the field. The recorded dynamics of such a quantum particle exhibits features closely related to Bloch oscillations and interband tunneling. In particular, we explore the regime of strong fields, demonstrating contrasting quantum behaviors: quantum resonances versus dynamical localization depending on whether the accumulated Bloch phase is a rational or irrational fraction of 2π.