ALBERT

Description: En el presente informe se analiza la información publicada sobre la ocurrencia de grandes sismos en el Perú, con el propósito de consolidar el posible escenario sísmico y de tsunami que pueda presentarse en el borde occidental de la región central del Perú y que afectaría a la ciudad de Lima Metropolitana y a la provincia Constitucional del Callao. Se considera como fuentes primarias los trabajos de investigación realizados por Tavera y Bernal (2005) “Distribución espacial de área de ruptura y lagunas sísmicas en el Borde Occidental de Perú”; Chlieh et al. (2011) “Interseismic coupling and seismic potential along the central Andes subduction zone”; Pulido et al. (2011) “Estimation of slip scenarios for megathrust earthquakes: a case study of Peru”; PNUD (2011) “Proyecto SIRAD”, Pulido et al. (2012) “Mega-earthquake rupture scenarios and strong motion simulations for Lima, Peru”; Condori y Tavera (2012), “Áreas probables de ruptura sísmica en el borde occidental del Perú, a partir de la variación del parámetro b”; Guardia y Tavera (2012) “Inferencias de la superficie de acoplamiento sísmico interplaca en el borde occidental del Perú”, y Flores y Tavera (2012) “Aplicación del algoritmo M8 en el borde occidental del Perú: Incrementos de probabilidad para la ocurrencia de grandes Terremotos”.

Description: Published

Description: Author(s): Michael Skotiniotis, Florian Fröwis, Wolfgang Dür, and Barbara Kraus We investigate quantum metrology using a Lie algebraic approach for a class of Hamiltonians, including local and nearest-neighbor interaction Hamiltonians. Using this Lie algebraic formulation, we identify and construct highly symmetric states that admit Heisenberg scaling in precision for phase est… [Phys. Rev. A 92, 022323] Published Mon Aug 10, 2015

Description: Author(s): Seungho Yang and Hyunseok Jeong We investigate how much amount of Greenberger-Horne-Zeilinger (GHZ) entanglement is required in order to prepare a given multipartite state by local operations and classical communication (LOCC). We present a LOCC procedure that asymptotically converts GHZ states into an arbitrary multipartite pure … [Phys. Rev. A 92, 022322] Published Mon Aug 10, 2015

Description: Author(s): Zheng-Yuan Xue, Jian Zhou, and Z. D. Wang To implement a set of universal quantum logic gates based on non-Abelian geometric phases, it is conventional wisdom that quantum systems beyond two levels are required, which is extremely difficult to fulfill for superconducting qubits and appears to be a main reason why only single-qubit gates wer… [Phys. Rev. A 92, 022320] Published Mon Aug 10, 2015

Description: Author(s): A. Walther, L. Rippe, Y. Yan, J. Karlsson, D. Serrano, A. N. Nilsson, S. Bengtsson, and S. Kröll We propose and analyze a high-fidelity readout scheme for a single-instance approach to quantum computing in rare-earth-ion-doped crystals. The scheme is based on using different elements as qubit and readout ions, where the readout ions are doped into the material at a much lower concentration than… [Phys. Rev. A 92, 022319] Published Mon Aug 10, 2015

Description: Author(s): Manuel Erhard, Hammam Qassim, Harjaspreet Mand, Ebrahim Karimi, and Robert W. Boyd There exists two prominent methods to transfer information between two spatially separated parties, namely Alice ( A ) and Bob ( B ): quantum teleportation and remote state preparation. However, the difference between these methods is, in the teleportation scheme, the state to be transferred is complete… [Phys. Rev. A 92, 022321] Published Mon Aug 10, 2015

Description: Author(s): J. A. Smith, D. B. Uskov, and L. Kaplan Here, we study the classical information capacity of a quantum channel, assuming linear optical encoding, as a function of available photons and optical modes. We present a formula for general channel capacity and show that this capacity is achieved without requiring the use of entangling operations… [Phys. Rev. A 92, 022324] Published Mon Aug 10, 2015

Description: Author(s): P. Bažant, H. Frydrych, G. Alber, and I. Jex Dynamical decoupling is a powerful method for protecting quantum information against unwanted interactions with the help of open-loop control pulses. Realistic control pulses are not ideal and may introduce additional systematic errors. We introduce a class of self-stabilizing pulse sequences capabl… [Phys. Rev. A 92, 022325] Published Mon Aug 10, 2015

Description: Author(s): Adam D. Bookatz, Edward Farhi, and Leo Zhou We consider the use of quantum error-detecting codes, together with energy penalties against leaving the code space, as a method for suppressing environmentally induced errors in Hamiltonian-based quantum computation. This method was introduced in Jordan et al. [ Phys. Rev. A 74 , 052322 (2006) ] in t… [Phys. Rev. A 92, 022317] Published Mon Aug 10, 2015

Description: Author(s): Tiantian Huan, Rigui Zhou, and Hou Ian We give a theoretical study of a double-cavity system in which a mechanical resonator beam is coupled to two cavity modes on both sides through radiation pressures. The indirect coupling between the cavities via the resonator sets up a correlation in the optomechanical entanglements between the two … [Phys. Rev. A 92, 022301] Published Mon Aug 03, 2015

Description: Author(s): M. R. Barros, O. J. Farías, A. Keller, T. Coudreau, P. Milman, and S. P. Walborn Interference phenomena of quantum systems have been studied in the context of fundamental aspects of quantum physics and are considered a necessary resource for quantum information. Here we investigate the interference of multiparticle wave packets in terms of modular variables, which is a natural a… [Phys. Rev. A 92, 022308] Published Wed Aug 05, 2015

Description: Author(s): Run-hua Shi, Yi Mu, Hong Zhong, and Shun Zhang We present and define a privacy-preserving problem called the oblivious set-member decision problem, which allows a server to decide whether a private secret of a user is a member of his private set in an oblivious manner. Namely, if the secret belongs to his private set, he does not know which memb… [Phys. Rev. A 92, 022309] Published Wed Aug 05, 2015

Description: The attenuation and velocity dispersion of sonic waves contain valuable information on the mechanical and hydraulic properties of the probed medium. An inherent complication arising in the interpretation of corresponding measurements is, however, that there are multiple physical mechanisms contributing to the energy dissipation and that the relative importance of the various contributions is difficult to unravel. To address this problem for the practically relevant case of terrestrial alluvial sediments, we analyse the attenuation and velocity dispersion characteristics of broad-band multifrequency sonic logs with dominant source frequencies ranging between 1 and 30 kHz. To adequately compensate for the effects of geometrical spreading, which is critical for reliable attenuation estimates, we simulate our experimental setup using a correspondingly targeted numerical solution of the poroelastic equations. After having applied the thus inferred corrections, the broad-band sonic log data set, in conjunction with a comprehensive suite of complementary logging data, allows for assessing the relative importance of a range of pertinent attenuation mechanisms. In doing so, we focus on the effects of wave-induced fluid flow over a wide range of scales. Our results indicate that the levels of attenuation due to the presence of mesoscopic heterogeneities in unconsolidated clastic sediments fully saturated with water are expected to be largely negligible. Conversely, Monte-Carlo-type inversions indicate that Biot's classical model permits to explain most of the considered data. Refinements with regard to the fitting of the observed attenuation and velocity dispersion characteristics are locally provided by accounting for energy dissipation at the microscopic scale, although the nature of the underlying physical mechanism remains speculative.

Description: Author(s): C. Grezes, B. Julsgaard, Y. Kubo, W. L. Ma, M. Stern, A. Bienfait, K. Nakamura, J. Isoya, S. Onoda, T. Ohshima, V. Jacques, D. Vion, D. Esteve, R. B. Liu, K. Mølmer, and P. Bertet We report the storage of microwave pulses at the single-photon level in a spin-ensemble memory consisting of 10 10 nitrogen-vacancy centers in a diamond crystal coupled to a superconducting L C resonator. The energy of the signal, retrieved 100 μ s later by spin-echo techniques, reaches 0.3 % of the ener… [Phys. Rev. A 92, 020301(R)] Published Fri Aug 07, 2015

Description: Author(s): Lin Zhang, Arun Kumar Pati, and Junde Wu In quantum information and communication two fundamental nonclassical features that one exploits in harnessing the true power of composite quantum systems are the interference and quantum correlations. We show how a concept akin to interference can be connected to entanglement and quantum correlatio… [Phys. Rev. A 92, 022316] Published Fri Aug 07, 2015

Description: Author(s): Fern H. E. Watson, Earl T. Campbell, Hussain Anwar, and Dan E. Browne Two-level quantum systems, qubits, are not the only basis for quantum computation. Advantages exist in using qudits, d -level quantum systems, as the basic carrier of quantum information. We show that color codes, a class of topological quantum codes with remarkable transversality properties, can be … [Phys. Rev. A 92, 022312] Published Fri Aug 07, 2015

Description: Author(s): Nikolay V. Vitanov Dynamical decoupling is an established tool for protecting the quantum state of a qubit from decoherence. This paper extends the simplest dynamical decoupling technique for qubits—the Carr-Purcell-Meiboom-Gill's two-pulse rephasing sequence—to qudits with an arbitrary number of states. The pulse seq… [Phys. Rev. A 92, 022314] Published Fri Aug 07, 2015

Description: Author(s): Wiesław Laskowski, Marcin Markiewicz, Danny Rosseau, Tim Byrnes, Kamil Kostrzewa, and Adrian Kołodziejski We describe a criterion for the detection of entanglement between two multiboson systems. The criterion is based on calculating correlations of Gell-Mann matrices with a fixed boson number on each subsystem. This applies naturally to systems such as two entangled spinor Bose-Einstein condensates. We… [Phys. Rev. A 92, 022339] Published Tue Aug 18, 2015

Description: Author(s): Xiao-Hang Cheng, Unai Alvarez-Rodriguez, Lucas Lamata, Xi Chen, and Enrique Solano We propose a physical implementation of time and spatial parity transformations, as well as Galilean boosts, in a trapped-ion quantum simulator. By embedding the simulated model into an enlarged simulating Hilbert space, these fundamental symmetry operations can be fully realized and measured with i… [Phys. Rev. A 92, 022344] Published Wed Aug 19, 2015

Description: Author(s): Vojtěch Kupčík and Radim Filip We discuss the deterministic Gaussian entangling procedure between continuous variables of two directly noninteracting oscillators. The oscillators can only couple to the same mediating oscillator, which is initially at arbitrary noisy state and can be lost after the procedure. Unitary idealization … [Phys. Rev. A 92, 022346] Published Fri Aug 21, 2015

Description: Author(s): Krzysztof Szczygielski and Robert Alicki The recently developed formalism of Markovian master equations for quantum open systems with external periodic driving is applied to the theory of dynamical decoupling by periodic control. This new approach provides a more detailed quantitative picture of this phenomenon applicable both to tradition… [Phys. Rev. A 92, 022349] Published Mon Aug 24, 2015

Description: Author(s): L. Latmiral, C. Di Franco, P. L. Mennea, and M. S. Kim Spin-chain models have been widely studied in terms of quantum information processes, for instance for the faithful transmission of quantum states. Here, we investigate the limitations of mapping this process to an equivalent one through a bosonic chain. In particular, we keep in mind experimental i… [Phys. Rev. A 92, 022350] Published Mon Aug 24, 2015

Description: Author(s): S. Allende, D. Altbir, and J. C. Retamal The simulated annealing algorithm, a method commonly used to calculate properties of condensed-matter systems, is used to calculate entanglement of formation for higher-dimensional mixed states. The method relies on representing a mixed state as a pure state in an enlarged Hilbert space, and on the … [Phys. Rev. A 92, 022348] Published Mon Aug 24, 2015

Description: Author(s): Joseph Bowles, Nicolas Brunner, and Marcin Pawłowski We consider networks featuring preparation, transformation, and measurement devices, in which devices exchange communication via mediating physical systems. We investigate the problem of testing the dimension of the mediating systems in the device-independent scenario, that is, based on observable d… [Phys. Rev. A 92, 022351] Published Mon Aug 24, 2015

Description: Author(s): Andreas Albrecht and Martin B. Plenio The impact of control sequences on the environmental coupling of a quantum system can be described in terms of a filter. Here we analyze how the coherent evolution of two interacting spins subject to periodic control pulses, using the example of a nitrogen vacancy center coupled to a nuclear spin, c… [Phys. Rev. A 92, 022340] Published Tue Aug 18, 2015

Description: Author(s): Thomas G. Wong and Andris Ambainis We identify a key difference between quantum search by discrete- and continuous-time quantum walks: a discrete-time walk typically performs one walk step per oracle query, whereas a continuous-time walk can effectively perform multiple walk steps per query while only counting query time. As a result… [Phys. Rev. A 92, 022338] Published Tue Aug 18, 2015

Description: Author(s): I. Bezděková, M. Štefaňák, and I. Jex The analysis of a physical problem simplifies considerably when one uses a suitable coordinate system. We apply this approach to the discrete-time quantum walks with coins given by 2 j + 1 -dimensional Wigner rotation matrices (Wigner walks), a model which was introduced in Miyazaki et al. [ Phys. Rev. A … [Phys. Rev. A 92, 022347] Published Mon Aug 24, 2015

Description: Author(s): Hong-Wei Li, Marcin Pawłowski, Ramij Rahaman, Guang-Can Guo, and Zheng-Fu Han In this work, we propose device-independent true random number expansion protocols based on noninequality paradoxes such as Hardy's and Cabello's nonlocality arguments, thus highlighting the noninequality paradox as an important resource for device-independent quantum-information processing, in part… [Phys. Rev. A 92, 022327] Published Tue Aug 11, 2015

Description: Author(s): Shi-Lei Su, Qi Guo, Hong-Fu Wang, and Shou Zhang Inspired by recent work [Carr and Saffman, Phys. Rev. Lett. 111 , 033607 (2013) ], we propose a simplified scheme to prepare the two-atom maximally entangled states via dissipative Rydberg pumping. Compared with the former scheme, the simplified one involves fewer classical laser fields and Rydberg in… [Phys. Rev. A 92, 022328] Published Wed Aug 12, 2015

Description: We investigate spatiotemporal variations of the crustal stress field orientation along the rupture zones of the 1999 August Izmit M w 7.4 and November Düzce M w 7.1 earthquakes at the North Anatolian Fault zone (NAFZ) in NW Turkey. Our primary focus is to elaborate on the relation between the state of the crustal stress field and distinct seismotectonic features as well as variations of coseismic slip within the seismogenic layer of the crust. To achieve this, we compile an extensive data base of hypocentres and first-motion polarities including a newly derived local hypocentre catalogue extending from 2 yr prior (1997) to 2 yr after (2001) the Izmit and Düzce main shocks. This combined data set allows studying spatial and temporal variations of stress field orientation along distinct fault segments for the pre- and post-seimic phase of the two large earthquakes in detail. Furthermore, the occurrence of two M  〉 7 earthquakes in rapid succession gives the unique opportunity to analyse the 87-d-long ‘inter-seismic phase’ between them. We use the MOTSI (first MOTion polarity Stress Inversion) procedure directly inverting first-motion polarities to study the stress field evolution of nine distinct segments. In particular, this allows to determine the stress tensor also for the pre- and post-seismic phases when no stable single-event focal mechanisms can be determined. We observe significantly different stress field orientations along the combined 200-km-long rupture in accordance with lateral variations of coseismic slip and seismotectonic setting. Distinct vertical linear segments of the NAFZ show either pure-strike slip behaviour or transtensional and normal faulting if located near pull-apart basins. Pull-apart structures such as the Akyazi and Düzce basins show a predominant normal faulting behaviour along the NAFZ and reflect clearly different characteristic from neighbouring strike-slip segments. Substantial lateral stress field heterogeneity following the two main shocks is observed that declines with time towards the post-seismic period that rather reflects the regional right-lateral strike-slip stress field.

Description: Author(s): Feihu Xu Measurement-device-independent quantum key distribution (MDI-QKD) can provide enhanced security compared to traditional QKD, and it constitutes an important framework for a quantum network with an untrusted network server. Still, a key assumption in MDI-QKD is that the sources are trusted. We propos… [Phys. Rev. A 92, 012333] Published Wed Jul 29, 2015

Description: Author(s): Max R. Atkin and Stefan Zohren We consider the expected violations of Bell inequalities from random pure states. More precisely, we focus on a slightly generalized version of the Collins-Gisin-Linden-Massar-Popescu inequality, which concerns Bell experiments of two parties, two measurement options, and N outcomes, and analyze the… [Phys. Rev. A 92, 012331] Published Wed Jul 29, 2015

Description: Author(s): Amit Mukherjee, Arup Roy, Some Sankar Bhattacharya, Subhadipa Das, Md. Rajjak Gazi, and Manik Banik Knowing the dimension of an unknown physical system has practical relevance, as dimensionality plays an important role in various information theoretic tasks. In this work we show that a modified version of Hardy's argument, which reveals the contradiction of quantum theory with local realism , turns… [Phys. Rev. A 92, 022302] Published Mon Aug 03, 2015

Description: Author(s): Debmalya Das, Shruti Dogra, Kavita Dorai, and Arvind We experimentally construct a three-qubit entangled W superposition ( W W ¯ ) state on an NMR quantum information processor. We give a measurement-based filtration protocol for the invertible local operation (ILO) that converts the W W ¯ state to the Greenberger-Horne-Zeilinger (GHZ) state, using a regist… [Phys. Rev. A 92, 022307] Published Wed Aug 05, 2015

Description: Author(s): P. Lougovski and D. B. Uskov Entanglement can effectively increase communication channel capacity as evidenced by dense coding that predicts a capacity gain of 1 bit when compared to entanglement-free protocols. However, dense coding relies on Bell states and when implemented using photons the capacity gain is bounded by 0.585 bi… [Phys. Rev. A 92, 022303] Published Tue Aug 04, 2015

Description: Author(s): Shi-Hai Sun, Feihu Xu, Mu-Sheng Jiang, Xiang-Chun Ma, Hoi-Kwong Lo, and Lin-Mei Liang The security of source has become an increasingly important issue in quantum cryptography. Based on the framework of measurement-device-independent quantum key distribution (MDI-QKD), the source becomes the only region exploitable by a potential eavesdropper (Eve). Phase randomization is a cornersto… [Phys. Rev. A 92, 022304] Published Tue Aug 04, 2015

Description: Author(s): Arpita Maitra, Sourya Joyee De, Goutam Paul, and Asim K. Pal A rational secret sharing scheme is a game in which each party responsible for reconstructing a secret tries to maximize his or her utility by obtaining the secret alone. Quantum secret sharing schemes, derived either from quantum teleportation or from quantum error correcting code, do not succeed w… [Phys. Rev. A 92, 022305] Published Tue Aug 04, 2015

Description: Author(s): Naihuan Jing, Shao-Ming Fei, Ming Li, Xianqing Li-Jost, and Tinggui Zhang We present a complete set of local unitary invariants for generic multiqubit systems which gives necessary and sufficient conditions for two states being local unitary equivalent. These invariants are canonical polynomial functions in terms of the generalized Bloch representation of the quantum stat… [Phys. Rev. A 92, 022306] Published Tue Aug 04, 2015

Description: The Piton de la Fournaise basaltic volcano, on La Réunion Island in the western Indian Ocean, is one of the most active volcanoes in the world. This volcano is classically considered as the surface expression of an upwelling mantle plume and its activity is continuously monitored, providing detailed information on its superficial dynamics and on the edifice structure. Deeper crustal and upper mantle structure under La Réunion Island is surprisingly poorly constrained, motivating this study. We used receiver function techniques to determine a shear wave velocity profile through the crust and uppermost mantle beneath La Réunion, but also at other seismic stations located on the hotspot track, to investigate the plume and lithosphere interaction and its evolution through time. Receiver functions (RFs) were computed at permanent broad-band seismic stations from the GEOSCOPE network (on La Réunion and Rodrigues), at IRIS stations MRIV and DGAR installed on Mauritius and Diego Garcia islands, and at the GEOFON stations KAAM and HMDM on the Maldives. We performed non-linear inversions of RFs through modelling of P -to- S conversions at various crustal and upper mantle interfaces. Joint inversion of RF and surface wave dispersion data suggests a much deeper Mohorovičić discontinuity (Moho) beneath Mauritius (~21 km) compared to La Réunion (~12 km). A magmatic underplated body may be present under La Réunion as a thin layer (≤3 km thick), as suggested by a previous seismic refraction study, and as a much thicker layer beneath other stations located on the hotspot track, suggesting that underplating is an important process resulting from the plume–lithosphere interaction. We find evidence for a strikingly low velocity layer starting at about 33 km depth beneath La Réunion that we interpret as a zone of partial melt beneath the active volcano. We finally observe low velocities below 70 km beneath La Réunion and below 50 km beneath Mauritius that could represent the base of the oceanic lithosphere.

Description: Author(s): Emily Adlam and Adrian Kent We examine the possibility of device-independent relativistic quantum bit commitment, introducing three relativistic quantum bit commitment schemes that offer device-independent security against hypothetical postquantum adversaries subject only to the no-signaling principle. We discuss the potential… [Phys. Rev. A 92, 022315] Published Fri Aug 07, 2015

Description: Author(s): Sheng Zhang and Yuexin Zhang So far, most existing single-shot quantum coin flipping (QCF) protocols have failed in a noisy quantum channel. Here, we present a nested-structure framework that makes it possible to achieve partially noise-tolerant QCF, due to a trade-off between the security and the justice correctness. It is sho… [Phys. Rev. A 92, 022313] Published Fri Aug 07, 2015

Description: Author(s): Xi-Han Li and Shohini Ghose We present two hyperentanglement concentration schemes for two-photon states that are partially entangled in the polarization and time-bin degrees of freedom. The first scheme distills a maximally hyperentangled state from two identical less-entangled states with unknown parameters via the Schmidt p... [Phys. Rev. A 91, 062302] Published Tue Jun 02, 2015

Description: Author(s): Ryan Sweke, Ilya Sinayskiy, Denis Bernard, and Francesco Petruccione We consider the problem of constructing a “universal set” of Markovian processes, such that any Markovian open quantum system, described by a one-parameter semigroup of quantum channels, can be simulated through sequential simulations of processes from the universal set. In particular, for quantum s... [Phys. Rev. A 91, 062308] Published Mon Jun 08, 2015

Description: Author(s): Dheeraj M N and Todd A. Brun Quantum walks can be defined in two quite distinct ways: discrete-time and continuous-time quantum walks (DTQWs and CTQWs). For classical random walks, there is a natural sense in which continuous-time walks are a limit of discrete-time walks. Quantum mechanically, in the discrete-time case, an addi... [Phys. Rev. A 91, 062304] Published Fri Jun 05, 2015

Description: Author(s): Rémi Blandino, Marco Barbieri, Philippe Grangier, and Rosa Tualle-Brouri The employ of a heralded noiseless linear amplifier has been proven as a useful tool for mitigating imperfections in quantum channels. Its analysis is usually conducted within specific frameworks, for which the set of input states for a given protocol is fixed. Here we obtain a more general descript... [Phys. Rev. A 91, 062305] Published Fri Jun 05, 2015

Description: The scattering of seismic waves travelling in the Earth is not only caused by random velocity heterogeneity but also by surface topography. Both factors are known to strongly affect ground-motion complexity even at relatively short distance from the source. In this study, we simulate ground motion with a 3-D finite-difference wave propagation solver in the 0–5 Hz frequency band using three topography models representative of the Swiss alpine region and realistic heterogeneous media characterized by the Von Karman correlation functions. Subsequently, we analyse and quantify the characteristics of the scattered wavefield in the near-source region. Our study shows that both topography and velocity heterogeneity scattering may excite large coda waves of comparable relative amplitude, especially at around 1 Hz, although large variability in space may occur. Using the single scattering model, we estimate average Q C values in the range 20–30 at 1 Hz, 36–54 at 1.5 Hz and 62–109 at 3 Hz for constant background velocity models with no intrinsic attenuation. In principle, envelopes of topography-scattered seismic waves can be qualitatively predicted by theoretical back-scattering models, while forward- or hybrid-scattering models better reproduce the effects of random velocity heterogeneity on the wavefield. This is because continuous multiple scattering caused by small-scale velocity perturbations leads to more gentle coda decay and envelope broadening, while topography abruptly scatters the wavefield once it impinges the free surface. The large impedance contrast also results in more efficient mode mixing. However, the introduction of realistic low-velocity layers near the free surface increases the complexity of ground motion dramatically and indicates that the role of topography in elastic waves scattering can be relevant especially in proximity of the source. Long-period surface waves can form most of the late coda, especially when intrinsic attenuation is taken into account. Our simulations indicate that both topography and velocity heterogeneity scattering may result in large ground-motion variability, characterized by standard deviation values in the range 0.2–0.5 also at short distance from the source. We conclude that both topography and velocity heterogeneity should be considered to correctly assess the ground-motion variability in earthquake scenario studies even at intermediate frequency.

Description: In this study, we have systematically investigated the influence of the parameters of the slip-weakening law and the size of nucleation asperity on dynamic rupture of a planar fault in full-space and half-space using the boundary integral equation method, in particular, the occurrence conditions for subshear (or sub-Rayleigh for strike-slip rupture) and supershear ruptures. Besides the well-known rupture styles of subshear (or sub-Rayleigh) and supershear, we defined a new kind of rupture style in this study, termed the ‘self-arresting rupture’, for which the rupture process can be autonomously arrested by itself without any outside interference (e.g. a high strength barrier). Based on the vast number of simulations, we obtained rupture phase diagrams for strike-slip and dip-slip ruptures vertically and obliquely embedded in half-space and full-space with different buried depths. The rupture phase diagram clearly illustrates the occurrence conditions of three kinds of rupture styles and the transitions between them. In full-space, the supershear transition is sensitive with the fault width. Owing to the influence of the free surface, the rupture in half-space becomes much more complicated comparing to the one in full-space. For a strike-slip fault with zero buried depth, all ruptures that occur within the parameter range for sub-Rayleigh ruptures in full-space case become supershear ruptures. This means that as long as a rupture is able to grow incessantly, it will always evolve into a supershear rupture. For dip-slip faults, however, ruptures will always propagate with subshear speed, although slip rate could be almost twice that of a strike-slip fault. Although the influence of the free surface is strong, it is limited to very shallow ruptures (i.e. buried depth 〈1 km). The rupture phase diagram discussed in this study could provide a new insight on earthquake rupture mechanics.

Description: Mainland Portugal, on the southwestern edge of the European continent, is located directly north of the boundary between the Eurasian and Nubian plates. It lies in a region of slow lithospheric deformation (〈5 mm yr –1 ), which has generated some of the largest earthquakes in Europe, both intraplate (mainland) and interplate (offshore). Some offshore earthquakes are nucleated on old and cold lithospheric mantle, at depths down to 60 km. The seismicity of mainland Portugal and its adjacent offshore has been repeatedly classified as diffuse. In this paper, we analyse the instrumental earthquake catalogue for western Iberia, which covers the period between 1961 and 2013. Between 2010 and 2012, the catalogue was enriched with data from dense broad-band deployments. We show that although the plate boundary south of Portugal is diffuse, in that deformation is accommodated along several distributed faults rather than along one long linear plate boundary, the seismicity itself is not diffuse. Rather, when located using high-quality data, earthquakes collapse into well-defined clusters and lineations. We identify and characterize the most outstanding clusters and lineations of epicentres and correlate them with geophysical and tectonic features (historical seismicity, topography, geologically mapped faults, Moho depth, free-air gravity, magnetic anomalies and geotectonic units). Both onshore and offshore, clusters and lineations of earthquakes are aligned preferentially NNE–SSW and WNW–ESE. Cumulative seismic moment and epicentre density decrease from south to north, with increasing distance from the plate boundary. Only few earthquake lineations coincide with geologically mapped faults. Clusters and lineations that do not match geologically mapped faults may correspond to previously unmapped faults (e.g. blind faults), rheological boundaries or distributed fracturing inside blocks that are more brittle and therefore break more easily than neighbour blocks. The seismicity map of western Iberia presented in this article opens important questions concerning the regional seismotectonics. This work shows that the study of low-magnitude earthquakes using dense seismic deployments is a powerful tool to study lithospheric deformation in slowly deforming regions, such as western Iberia, where high-magnitude earthquakes occur with long recurrence intervals.

Description: Author(s): Xiangming Hu For dark resonance, one of the most remarkable coherent effects in light-matter interactions, it has commonly been expected that squeezing and entanglement, if existent, are formed via coherent evolutions against dissipation. Contrary to the expectations, here we show that dissipation generates enta… [Phys. Rev. A 92, 022329] Published Wed Aug 12, 2015

Description: Author(s): Benedikt Richter and Yasser Omar We study the entanglement of families of Unruh modes in the Bell states | Φ ± 〉 = 1 / 2 ( | 00 〉 ± | 11 〉 ) and | Ψ ± 〉 = 1 / 2 ( | 01 〉 ± | 10 〉 ) shared by two accelerated observers and find fundamental differences in the robustness of entanglement against acceleration for these states. States Ψ ± are entangled for all finite acc… [Phys. Rev. A 92, 022334] Published Fri Aug 14, 2015

Description: Author(s): Yu-Qian Zhou, Hong-Wei Li, Yu-Kun Wang, Dan-Dan Li, Fei Gao, and Qiao-Yan Wen By proposing device-independent protocols, Pironio et al. [ Nature (London) 464 , 1021 (2010) ] and Colbeck et al. [ Nat. Phys. 8 , 450 (2012) ] proved that new randomness can be generated by using perfectly free random sources or partially free ones as seed. Subsequently, Li et al. [ Phys. Rev. A 84 , 0343… [Phys. Rev. A 92, 022331] Published Thu Aug 13, 2015

Description: Author(s): Cédric Bény and Tobias J. Osborne We propose a general formulation of the renormalization group (RG) as a family of quantum channels which connect the microscopic physical world to the observable world at some scale. By endowing the set of quantum states with an operationally motivated information geometry, we induce the space of Ha… [Phys. Rev. A 92, 022330] Published Thu Aug 13, 2015

Description: Author(s): M. A. Fogarty, M. Veldhorst, R. Harper, C. H. Yang, S. D. Bartlett, S. T. Flammia, and A. S. Dzurak We show that nonexponential fidelity decays in randomized benchmarking experiments on quantum-dot qubits are consistent with numerical simulations that incorporate low-frequency noise and correspond to a control fidelity that varies slowly with time. By expanding standard randomized benchmarking ana… [Phys. Rev. A 92, 022326] Published Tue Aug 11, 2015

Description: Author(s): Svetoslav S. Ivanov and Nikolay V. Vitanov We design composite controlled- phase gates, which compensate errors in the phase of a single gate. The errors can be of various natures, such as relative, absolute, or both. We present composite sequences which are robust to relative errors up to the sixth order with the number of the constituent ga… [Phys. Rev. A 92, 022333] Published Fri Aug 14, 2015

Description: Author(s): Luke C. G. Govia, Emily J. Pritchett, B. L. T. Plourde, Maxim G. Vavilov, R. McDermott, and Frank K. Wilhelm Parity measurement is a central tool for many quantum information processing tasks. In this work, we propose a method to directly measure two- and four-qubit parity with low overhead in hardware and software while remaining robust to experimental imperfections. Our scheme relies on dispersive qubit-… [Phys. Rev. A 92, 022335] Published Fri Aug 14, 2015

Description: Author(s): Chun-Hui Zhang, Sun-Long Luo, Guang-Can Guo, and Qin Wang We present a scheme for the practical decoy-state quantum key distribution with heralded single-photon source. In this scheme, only two-intensity decoy states are employed. However, its performance can approach the asymptotic case of using infinite decoy states. We compare it with the standard three… [Phys. Rev. A 92, 022332] Published Fri Aug 14, 2015

Description: The accurate estimation of dispersion curves has been a key issue for ensuring high quality in geophysical surface wave exploration. Many studies have been carried out on the generation of a high-resolution dispersion image from array measurements. In this study, the sparse signal representation and reconstruction techniques are employed to obtain the high resolution Rayleigh-wave dispersion image from seismic wave data. First, a sparse representation of the seismic wave data is introduced, in which the signal is assumed to be sparse in terms of wave speed. Then, the sparse signal is reconstructed by optimization using l 1 -norm regularization, which gives the signal amplitude spectrum as a function of wave speed. A dispersion image in the f – v domain is generated by arranging the sparse spectra for all frequency slices in the frequency range. Finally, to show the efficiency of the proposed approach, the Surfbar-2 field test data, acquired by B. Luke and colleagues at the University of Nevada Las Vegas, are analysed. By comparing the real-field dispersion image with the results from other methods, the high mode-resolving ability of the proposed approach is demonstrated, particularly for a case with strongly coherent modes.

Description: Author(s): Yan-Ling Wang, Mao-Sheng Li, Zhu-Jun Zheng, and Shao-Ming Fei We study the local indistinguishability of mutually orthogonal product basis quantum states in the high-dimensional quantum system. In the quantum system of C d ⊗ C d , where d is odd, Zhang et al. [Z.-C. Zhang et al. , Phys. Rev. A 90 , 022313 (2014) ] have constructed d 2 orthogonal product basis quantum … [Phys. Rev. A 92, 032313] Published Thu Sep 10, 2015

Description: Author(s): W. L. Boyajian and B. Kraus Since several years, the preparation and manipulation of a small number of quantum systems in a controlled and coherent way is feasible in many experiments. In fact, these experiments are nowadays commonly used for quantum simulation and quantum computation. As recently shown, such a system can, how… [Phys. Rev. A 92, 032323] Published Thu Sep 24, 2015

Description: We analyse daily cross-correlation computed from continuous records by permanent stations operating in vicinity of the Klyuchevskoy group of volcanoes (Kamchatka). Seismic waves generated by volcanic tremors are clearly seen on the cross-correlations between some pairs of stations as strong signals at frequencies between 0.2 and 2 Hz and with traveltimes typically shorter than those corresponding to interstation propagation. First, we develop a 2-D source-scanning algorithm based on summation of the envelops of cross-correlations to detect seismic tremors and to determine locations from which the strong seismic energy is continuously emitted. In an alternative approach, we explore the distinctive character of the cross-correlation waveforms corresponding to tremors emitted by different volcanoes and develop a phase-matching method for detecting volcanic tremors. Application of these methods allows us to detect and to distinguish tremors generated by the Klyuchevskoy and the Tolbachik, volcanoes and to monitor evolution of their intensity in time.

Description: In geophysical inversion, inferences of Earth's properties from sparse data involve a trade-off between model complexity and the spatial resolving power. A recent Markov chain Monte Carlo (McMC) technique formalized by Green, the so-called trans-dimensional samplers, allows us to sample between these trade-offs and to parsimoniously arbitrate between the varying complexity of candidate models. Here we present a novel framework using trans-dimensional sampling over tree structures. This new class of McMC sampler can be applied to 1-D, 2-D and 3-D Cartesian and spherical geometries. In addition, the basis functions used by the algorithm are flexible and can include more advanced parametrizations such as wavelets, both in Cartesian and Spherical geometries, to permit Bayesian multiscale analysis. This new framework offers greater flexibility, performance and efficiency for geophysical imaging problems than previous sampling algorithms. Thereby increasing the range of applications and in particular allowing extension to trans-dimensional imaging in 3-D. Examples are presented of its application to 2-D seismic and 3-D teleseismic tomography including estimation of uncertainty.

Description: Rupture properties, such as rupture direction, length, propagation speed and source duration, provide important insights into earthquake mechanisms. One approach to estimate these properties is to investigate the body-wave duration that depends upon the relative location of the station with respect to the rupture direction. Under the assumption that the propagation is unilateral, the duration can be expressed as a function of the dip and azimuth of the rupture. Examination of duration measurements with respect to both the take-off angle and the azimuth is crucial to obtain robust estimates of rupture parameters, especially for nearly vertical rupture propagation. Moreover, limited data coverage, such as using only teleseismic data, can bias the source duration estimate for dipping ruptures, and this bias can map into estimates of other source properties such as rupture extent and rupture speed. Based upon this framework, we introduce an inversion scheme that uses the duration measurements to obtain four parameters: the source duration, a measure of the rupture extent and speed, and dip and azimuth of the rupture propagation. The method is applied to two deep-focus events in the Sea of Okhotsk region, an M w 7.7 event that occurred on 2012 August 14 and an M w 8.3 event from 2013 May 24. The source durations are 26 ± 1 and 37 ± 1 s, and rupture speeds are 49 ± 4 per cent and 26 ± 3 per cent of shear wave speed for the M w 7.7 and 8.3 events, respectively. The azimuths of the two ruptures are parallel to the trench, but are in opposite directions. The dips of the M w 7.7 and 8.3 events are constrained to be 48° ± 8° downdip and 19° ± 8° updip, respectively. The fit to the data is significantly poorer for the M w 8.3 event than the M w 7.7 event, suggesting that the unilateral rupture may not be a good assumption. The analysis is expanded into a multi-episode model, and a secondary episode is determined for the M w 8.3 event in the southeast direction. The two-episode model gives a better fit to the data than the unilateral model and is compatible with the back-projection analysis, demonstrating that the rupture propagation of the M w 8.3 event is complex.

Description: Author(s): Azam Mani and Vahid Karimipour We introduce the concepts of cohering and decohering power of quantum channels. Using the axiomatic definition of the coherence measure, we show that the optimization required for calculations of these measures can be restricted to pure input states and hence greatly simplified. We then use two exam… [Phys. Rev. A 92, 032331] Published Tue Sep 29, 2015

Description: Author(s): M. Usman, Asif Ilyas, and Khalid Khan We investigate entanglement and quantum phase transition in a two-dimensional Heisenberg anisotropic spin- 1 / 2 XY model, using the quantum renormalization-group method (QRG) on a square lattice of N × N sites. The entanglement through geometric average of concurrences is calculated after each step of th… [Phys. Rev. A 92, 032327] Published Mon Sep 28, 2015

Description: Author(s): Jingliang Gao We present two quantum union bounds for sequential projective measurements. These bounds estimate the disturbance accumulation and probability of outcomes when the measurements are performed sequentially. These results are based on a trigonometric representation of quantum states and should have wid… [Phys. Rev. A 92, 052331] Published Tue Nov 24, 2015

Description: Author(s): Long Huang, Bo You, Xiaohua Wu, and Tao Zhou In this work, a quantum error correction (QEC) procedure with the concatenated five-qubit code is used to construct a near-perfect effective qubit channel (with a error below 10 − 5 ) from arbitrary noise channels. The exact performance of the QEC is characterized by a Choi matrix, which can be obtaine… [Phys. Rev. A 92, 052320] Published Wed Nov 18, 2015

Description: Author(s): Adrien Feix, Mateus Araújo, and Časlav Brukner In a variant of communication complexity tasks, two or more separated parties cooperate to compute a function of their local data, using a limited amount of communication. It is known that communication of quantum systems and shared entanglement can increase the probability for the parties to arrive… [Phys. Rev. A 92, 052326] Published Fri Nov 20, 2015

Description: Author(s): N. S. Simonović and R. G. Nazmitdinov Quantum entanglement is analyzed thoroughly in the case of the ground and lowest states of two-electron axially symmetric quantum dots under a perpendicular magnetic field. The individual-particle and the center-of-mass representations are used to study the entanglement variation at the transition f… [Phys. Rev. A 92, 052332] Published Tue Nov 24, 2015

Description: Author(s): D. Baguette, F. Damanet, O. Giraud, and J. Martin We investigate multiqubit permutation-symmetric states with maximal entropy of entanglement. Such states can be viewed as particular spin states, namely anticoherent spin states. Using the Majorana representation of spin states in terms of points on the unit sphere, we analyze the consequences of a … [Phys. Rev. A 92, 052333] Published Tue Nov 24, 2015

Description: Author(s): Eugene Dumitrescu and Travis S. Humble We present methods for the direct characterization of quantum dynamics in which both the principal and ancilla systems undergo noisy processes. Using a concatenated error detection code, we discriminate between located and unlocated errors on the principal system in what amounts to filtering of anci… [Phys. Rev. A 92, 052329] Published Mon Nov 23, 2015

Description: We take account of the effect of Earth's surface topography in quasi-dynamic earthquake cycle simulations using a boundary integral equation method. While we have so far assumed a homogeneous elastic half-space medium with a flat free surface, Earth's actual surface topography is complicated. Here, we constructed new slip response functions in half-space with an arbitrarily shaped surface topography in which we used slip response functions in full-space by introducing imaginary free surface cells in addition to embedded fault ones. By comparing analytical slip response functions in the case of a flat surface overlying half-space with the new ones, we developed a computationally efficient method for setting the Earth's surface region, which was divided into cells with the appropriate sizes depending on the fault source cell depth to maintain the computational accuracy. With these new slip response functions, we simulated simple interplate earthquake cycles in the region close to the Japan Trench, off Miyagi, Tohoku, in northeast Japan, which has the amplitude of 7 km in depth. Compared with the case where the flat surface level was set at the trench depth, the slip response functions for the case where actual seafloor topography was used had smaller amplitudes. Hence, the actual topography produces smaller recurrence times for earthquake cycles than that for the flat surface case. These effects of the actual Earth's surface topography mainly come from changes in the distance between the surface and the fault compared with the flat surface case. Changes in the slip response function also represent changes in the fault stiffness of the system. Considering the actual topography of the Earth's surface to be convex upwards as opposed to the flat, the fault stiffness becomes larger compared to the case of the flat Earth's surface. This leads to a change in the frictional instability, and sometime leads to the change in the way of rupture.

Description: Author(s): Robert McConnell, Colin Bruzewicz, John Chiaverini, and Jeremy Sage Anomalous motional heating is a major obstacle to scalable quantum information processing with trapped ions. Although the source of this heating is not yet understood, several previous studies suggest that noise due to surface contaminants is the limiting heating mechanism in some instances. We demo… [Phys. Rev. A 92, 020302(R)] Published Fri Aug 28, 2015

Description: Author(s): Paul Skrzypczyk and Daniel Cavalcanti We show how to construct loss-tolerant linear steering inequalities using a generic set of von Neumann measurements that are violated by d -dimensional states, and that rely only upon a simple property of the set of measurements used (the maximal overlap between measurement directions). Using these i… [Phys. Rev. A 92, 022354] Published Fri Aug 28, 2015

Description: Author(s): Benjamin Yadin and Vlatko Vedral We suggest a way to quantify a type of macroscopic entanglement via distillation of Greenberger-Horne-Zeilinger states by local operations and classical communication. We analyze how this relates to an existing measure of quantum macroscopicity based on the quantum Fisher information in several exam… [Phys. Rev. A 92, 022356] Published Fri Aug 28, 2015

Description: Author(s): Avatar Tulsi A general quantum search algorithm aims to evolve a quantum system from a known source state | s 〉 to an unknown target state | t 〉 . It uses a diffusion operator D s that has the source state as one of its eigenstates and I t , where I ψ denotes the selective phase inversion of the | ψ 〉 state. It evolves | s 〉 … [Phys. Rev. A 92, 022353] Published Thu Aug 27, 2015

Description: Author(s): P. Sekatski, M. Skotiniotis, and W. Dür The no-signaling principle arising from the finite speed of light is considered, and it is shown how this simple principle directly leads to tight bounds for various quantum communication tasks. [Phys. Rev. A 92, 022355] Published Fri Aug 28, 2015

Description: The fate of subducted slabs is enigmatic, yet intriguing. We analyse seismic arrivals at ~20–50 s after the direct P wave in an array in northeast China (NECESSArray) recordings of four deep earthquakes occurring beneath the west-central Pacific subduction zones (from the eastern Indonesia to Tonga region). We employ the array analysing techniques of fourth root vespagram and beam-forming analysis to constrain the slowness and backazimuth of later arrivals. Our analyses reveal that these arrivals have a slightly lower slowness value than the direct P wave and the backazimuth deviates slightly from the great circle direction. Along with calculation of 1-D synthetic seismograms, we conclude that the later arrival is corresponding to an energy of S -to- P converted at a scatterer below the sources. Total five scatterers are detected at depths varying from ~700 to 1110 km in the study region. The past subducted oceanic crust most likely accounts for the seismic scatterers trapped in the mid-mantle beneath the west-central subduction zones. Our observation in turn reflects that oceanic crust at least partly separated from subducted oceanic lithosphere and may be trapped substantially in the mid-mantle surrounding subduction zones, in particular in the western Pacific subduction zones.

Description: Author(s): E. Shchukin and P. van Loock We derive a hierarchy of continuous-variable multipartite entanglement conditions in terms of second-order moments of position and momentum operators that generalize existing criteria. Each condition corresponds to a convex optimization problem which, given the covariance matrix of the state, can be… [Phys. Rev. A 92, 042328] Published Mon Oct 26, 2015

Description: Author(s): Chang-long Zhu, Nan Yang, Yu-xi Liu, Franco Nori, and Jing Zhang We present a method for quantum entanglement distribution over a so-called code-division multiple-access network, in which two pairs of users share the same quantum channel to transmit information. The main idea of this method is to use different broadband chaotic phase shifts, generated by electro-… [Phys. Rev. A 92, 042327] Published Mon Oct 26, 2015

Description: We examine spatio-temporal patterns of microseismicity recorded during one month in an underground mine by addressing three key questions: (1) where does the seismicity occur? (2) Why does it occur in these locations? and (3) what triggers it? To obtain accurate locations, we perform a multiplet analysis and use a modified version of the double-difference (DD) relocation method. This approach leads to highly accurate relative event locations and requires groups of multiplets only. Most of the 281 relocated events are close to the main shaft and tunnels; thus we postulate seismicity is facilitated by stresses associated with the potential for subsidence in addition to the hoop stresses acting on the two vertical shafts. Most events occurred during certain hours of the day and there is a 68 per cent correlation with reported rock removal; therefore, it is likely they were triggered by static and dynamic stress perturbations caused by the transportation of debris along tunnels instead of our initial guess that blasting was the principal causative mechanism. Given that seismicity is present around the main shaft but absent close to the second one, we conclude that for seismicity to occur both a favourable stress state and additional external perturbing forces must exist, thus leading to dynamic event triggering in an initially stable stress situation. This analysis provides more insight into anthropogenic processes that might trigger seismicity, thereby facilitating identification of hazardous and potential damage areas in mine settings.

Description: We present synthetic tests of 2-D adjoint tomography of surface wave traveltimes obtained by the ambient noise cross-correlation analysis across the Czech Republic. The data coverage may be considered perfect for tomography due to the density of the station distribution. Nevertheless, artefacts in the inferred velocity models arising from the data noise may be still observed when weak regularization (Gaussian smoothing of the misfit gradient) or too many iterations are considered. To examine the effect of the regularization and iteration number on the performance of the tomography in more detail we performed extensive synthetic tests. Instead of the typically used (although criticized) checkerboard test, we propose to carry out the tests with two different target models—simple smooth and complex realistic models. The first test reveals the sensitivity of the result on the data noise, while the second helps to analyse the resolving power of the data set. For various noise and Gaussian smoothing levels, we analysed the convergence towards (or divergence from) the target model with increasing number of iterations. Based on the tests we identified the optimal regularization, which we then employed in the inversion of 16 and 20 s Love-wave group traveltimes.

Description: Least-squares migration (LSM) is a linearized inversion technique for subsurface reflectivity estimation. Compared to conventional migration algorithms, it can improve spatial resolution significantly with a few iterative calculations. There are three key steps in LSM, (1) calculate data residuals between observed data and demigrated data using the inverted reflectivity model; (2) migrate data residuals to form reflectivity gradient and (3) update reflectivity model using optimization methods. In order to obtain an accurate and high-resolution inversion result, the good estimation of inverse Hessian matrix plays a crucial role. However, due to the large size of Hessian matrix, the inverse matrix calculation is always a tough task. The limited-memory BFGS (L-BFGS) method can evaluate the Hessian matrix indirectly using a limited amount of computer memory which only maintains a history of the past m gradients (often m 〈 10). We combine the L-BFGS method with least-squares pre-stack Kirchhoff depth migration. Then, we validate the introduced approach by the 2-D Marmousi synthetic data set and a 2-D marine data set. The results show that the introduced method can effectively obtain reflectivity model and has a faster convergence rate with two comparison gradient methods. It might be significant for general complex subsurface imaging.

Description: We present a method for high-resolution imaging of lithospheric structures based on full waveform inversion of teleseismic waveforms. We model the propagation of seismic waves using our recently developed direct solution method/spectral-element method hybrid technique, which allows us to simulate the propagation of short-period teleseismic waves through a regional 3-D model. We implement an iterative quasi-Newton method based upon the L-BFGS algorithm, where the gradient of the misfit function is computed using the adjoint-state method. Compared to gradient or conjugate-gradient methods, the L-BFGS algorithm has a much faster convergence rate. We illustrate the potential of this method on a synthetic test case that consists of a crustal model with a crustal discontinuity at 25 km depth and a sharp Moho jump. This model contains short- and long-wavelength heterogeneities along the lateral and vertical directions. The iterative inversion starts from a smooth 1-D model derived from the IASP91 reference Earth model. We invert both radial and vertical component waveforms, starting from long-period signals filtered at 10 s and gradually decreasing the cut-off period down to 1.25 s. This multiscale algorithm quickly converges towards a model that is very close to the true model, in contrast to inversions involving short-period waveforms only, which always get trapped into a local minimum of the cost function.

Description: Author(s): Ying Li In this paper, we show how to use low-fidelity operations to control the dynamics of quantum systems. Noisy operations usually drive a system to evolve into a mixed state and damage the coherence. Sometimes frequent noisy operations result in the coherent evolution of a subsystem, and the dynamics o... [Phys. Rev. A 91, 052328] Published Wed May 27, 2015

Description: Author(s): Paolo Zanardi and Lorenzo Campos Venuti Quantum information can be encoded in the set of steady states (SSS) of a driven-dissipative system. Nonsteady states are separated by a large dissipative gap that adiabatically decouples them while the dynamics inside the SSS is governed by an effective, dissipation-projected, Hamiltonian. The latt... [Phys. Rev. A 91, 052324] Published Tue May 26, 2015

Description: We analyse the physics and geometry of trade-offs between Earth structure and noise sources in interstation noise correlations. Our approach is based on the computation of off-diagonal Hessian elements that describe the extent to which variations in noise sources can compensate for variations in Earth structure without changing the misfit beyond the measurement uncertainty. Despite the fact that all ambient noise inverse problems are special in terms of their receiver configuration and data, some general statements concerning source-structure trade-offs can be made: (i) While source-structure trade-offs may be reduced to some extent by clever measurement design, there are inherent trade-offs that can generally not be avoided. These inherent trade-offs may lead to a mispositioning of structural heterogeneities when the noise source distribution is unknown. (ii) When attenuation is weak, source-structure trade-offs in ambient noise correlations are a global phenomenon, meaning that there is no noise source perturbation that does not trade-off with some Earth structure, and vice versa. (iii) The most significant source-structure trade-offs occur within two elliptically shaped regions connecting a potential noise source perturbation to each one of the receivers. (iv) Far from these elliptical regions, only small-scale structure can trade off against changes in the noise source. (v) While source-structure trade-offs mostly decay with increasing attenuation, they are nearly unaffected by attenuation when the noise source perturbation is located near the receiver-receiver line. This work is intended to contribute to the development of joint source-structure inversions of ambient noise correlations, and in particular to an understanding of the extent to which source-structure trade-offs may be reduced. It furthermore establishes the foundation of future resolution analyses that properly quantify trade-offs between noise sources and Earth structure.

Description: Reactive flow at depth (either related to underground activities, like enhancement of hydrocarbon recovery and CO 2 storage, or to natural flow like in hydrothermal zones) can alter fractures’ topography, which might in turn change their seismic responses. Depending on the flow and reaction rates, instability of the dissolution front can lead to a wormhole-like pronounced erosion pattern. In a fractal structure of rupture process, we question how the perturbation related to well-spaced long channels alters rupture propagation initiated on a weak plane and eventually the statistical feature of rupture appearance in frequency–magnitude distribution (FMD). Contrary to intuition, a spatially uniform dissolution is not the most remarkable case, since it affects all the events proportionally to their sizes leading to a downward translation of FMD: the slope of FMD ( b -value) remains unchanged. The parameter–space study shows that the increase of b -value (of 0.08) is statistically significant for optimum characteristics of the erosion pattern with spacing to length ratio of the order of ~1/40: large-magnitude events are more significantly affected leading to an imbalanced distribution in the magnitude bins of the FMD. The larger the spacing, the lower the channel's influence. Besides, a spatial analysis shows that the local seismicity anomaly concentrates in a limited zone around the channels: this opens perspective for detecting these eroded regions through high-resolution imaging surveys.

Description: Author(s): Masakazu Yoshida, Gen Kimura, Takayuki Miyadera, Hideki Imai, and Jun Cheng We discuss the so-called mean king's problem, a retrodiction problem among noncommutative observables, in the context of error detection. Describing the king's measurement effectively by a single error operation, we give a solution of the mean king's problem using quantum error-correcting codes. The... [Phys. Rev. A 91, 052326] Published Tue May 26, 2015

Description: The Anatolian Plate is composed of different lithospheric blocks and ribbon continents amalgamated during the closure of the Paleotethys Ocean and Neotethys Ocean along a subduction margin. Using ambient noise tomography, we investigate the crustal and uppermost mantle shear wave velocity structure of the Anatolian Plate. A total of 215 broad-band seismic stations were used spanning 7 yr of recording to compute 13 778 cross-correlations and obtain Rayleigh wave dispersion measurements for periods between 8 and 40 s. We then perform a shear wave inversion to calculate the seismic velocity structure of the crust and uppermost mantle. Our results show that the overall crustal shear wave velocities of the Anatolian crust are low (~3.4 km s –1 ), indicative of a felsic overall composition. We find that prominent lateral seismic velocity gradients correlate with Tethyan suture zones, supporting the idea that the neotectonic structures of Turkey are exploiting the lithospheric weaknesses associated with the amalgamation of Anatolia. Anomalously slow shear wave velocities (~3.15 km s –1 at 25 km) are located in the western limb of the Isparta Angle in southwestern Turkey. In the upper crust, we find that these low shear wave velocities correlate well with the projected location of a carbonate platform unit (Bey Dağlari) beneath the Lycian Nappe complex. In the lower crust and upper mantle of this region, we propose that the anomalously slow velocities are due to the introduction of aqueous fluids related to the underplating of accretionary material from the underthrusting of a buoyant, attenuated continental fragment similar to the Eratosthenes seamount. We suggest that this fragment controlled the location of the formation of the Subduction-Transform Edge Propagator fault in the eastern Aegean Sea during rapid slab rollback of the Aegean Arc in early Miocene times. Lastly, we observe that the uppermost mantle beneath continental Anatolia is generally slow (~4.2 km s –1 ), indicating higher than usual temperatures consistent with the influx of asthenosphere to shallow depths as a result of the segmentation and break-up of the subducting African lithosphere.

Description: The H/V spectral ratio has emerged as a single station method within the seismic ambient noise analysis field by its capability to quickly estimate the frequency of resonance at a site and through inversion the average profile information. Although it is easy to compute from experimental data, its counter theoretical part is not obvious when building a forward model which can help in reconstructing the derived H/V spectrum. This has led to the simplified assumption that the noise wavefield is mainly composed of Rayleigh waves and the derived H/V often used without further correction. Furthermore, only the right (and left) flank around the H/V peak frequency is considered in the inversion for the subsurface 1-D shear wave velocity profile. A new theoretical approach for the interpretation of the H/V spectral ratio has been presented by Sánchez-Sesma et al. In this paper, the fundamental idea behind their theory is presented as it applies to receivers at depth. A smooth H/V( z , f ) spectral curve on a broad frequency range is obtained by considering a fine integration step which is in turn time consuming. We show that for practical purposes and in the context of inversion, this can be considerably optimized by using a coarse integration step combined with the smoothing of the corresponding directional energy density (DED) spectrum. Further analysis shows that the obtained H/V( z , f ) spectrum computed by the mean of the imaginary part of Green's function method could also be recovered using the reflectivity method for a medium well illuminated by seismic sources. Inversion of synthetic H/V( z , f ) spectral curve is performed for a single layer over a half space. The striking results allow to potentially use the new theory as a forward computation of the H/V( z , f ) to fully invert the experimental H/V spectral ratio at the corresponding depth for the shear velocity profile ( Vs ) and additionally the compressional velocity profile ( Vp ) using receivers both at the surface and in depth. We use seismic ambient noise data in the frequency range of 0.2–50 Hz recorded at two selected sites in Germany where borehole information is also available. The obtained 1-D Vs and Vp profiles are correlated with geological log information. Results from shallow geophysical experiment are also used for comparison.

Description: The 1000-km-long left-lateral Dead Sea fault is a major tectonic structure of the oriental Mediterranean basin, bounding the Arabian Plate to the west. The fault is located in a region with an exceptionally long and rich historical record, allowing to document historical seismicity catalogues with unprecedented level of details. However, if the earthquake time series is well documented, location and lateral extent of past earthquakes remain often difficult to establish, if only based on historical testimonies. We excavated a palaeoseismic trench in a site located in a kilometre-size extensional jog, south of the Dead Sea, in the Wadi Araba. Based on the stratigraphy exposed in the trench, we present evidence for nine earthquakes that produced surface ruptures during a time period spanning 5000 yr. Abundance of datable material allows us to tie the five most recent events to historical earthquakes with little ambiguities, and to constrain the possible location of these historical earthquakes. The events identified at our site are the 1458 C.E., 1212 C.E., 1068 C.E., one event during the 8th century crisis, and the 363 C.E. earthquake. Four other events are also identified, which correlation with historical events remains more speculative. The magnitude of earthquakes is difficult to assess based on evidence at one site only. The deformation observed in the excavation, however, allows discriminating between two classes of events that produced vertical deformation with one order of amplitude difference, suggesting that we could distinguish earthquakes that started/stopped at our site from earthquakes that potentially ruptured most of the Wadi Araba fault. The time distribution of earthquakes during the past 5000 yr is uneven. The early period shows little activity with return interval of ~500 yr or longer. It is followed by a ~1500-yr-long period with more frequent events, about every 200 yr. Then, for the past ~550 yr, the fault has switched back to a quieter mode with no significant earthquake along the entire southern part of the Dead Sea fault, between the Dead Sea and the Gulf of Aqaba. We computed the Coefficient of Variation for our site and three other sites along the Dead Sea fault, south of Lebanon, to compare time distribution of earthquakes at different locations along the fault. With one exception at a site located next to Lake Tiberias, the three other sites are consistent to show some temporal clustering at the scale of few thousands years.

Description: Author(s): Jisho Miyazaki, Michal Hajdušek, and Mio Murao In measurement-based quantum computation (MBQC), elementary quantum operations can be more parallelized than the quantum circuit model by employing a larger Hilbert space of graph states used as the resource. Thus MBQC can be regarded as a method of quantum computation where the temporal resource de... [Phys. Rev. A 91, 052302] Published Mon May 04, 2015

Description: Author(s): Clarice D. Aiello and Paola Cappellaro Indirect control of qubits by a quantum actuator has been proposed as an appealing strategy to manipulate qubits that couple only weakly to external fields. While universal quantum control can be easily achieved when the actuator-qubit coupling is anisotropic, the efficiency of this approach is less... [Phys. Rev. A 91, 042340] Published Thu Apr 30, 2015

Description: Author(s): Ulrike Herzog We study the discrimination of N mixed quantum states in an optimal measurement that maximizes the probability of correct results while the probability of inconclusive results is fixed at a given value. After considering the discrimination of N states in a d -dimensional Hilbert space, we focus on th... [Phys. Rev. A 91, 042338] Published Wed Apr 29, 2015

Description: Author(s): Bing Qi and George Siopsis Position-based quantum cryptography (PBQC) allows a party to use its geographical location as its only credential to implement various cryptographic protocols. Such a protocol may lead to important applications in practice. Although it has been shown that any PBQC protocol is breakable if the advers... [Phys. Rev. A 91, 042337] Published Tue Apr 28, 2015

Description: Author(s): Tomoyuki Morimae We show that at least 2 k T ln 2 of heat dissipation per qubit (in the register of a simulated circuit) occurs in measurement-based quantum computation according to Landauer's principle. This result is derived by using only the fundamental fact that quantum physics respects the no-signaling principle. [Phys. Rev. A 91, 042335] Published Tue Apr 28, 2015

Description: Author(s): Jaehak Lee, Se-Wan Ji, Jiyong Park, and Hyunchul Nha A long-standing problem on the classical capacity of bosonic Gaussian channels has recently been resolved by proving the minimum output entropy conjecture. It is also known that the ultimate capacity quantified by the Holevo bound can be achieved asymptotically by using an infinite number of channel... [Phys. Rev. A 91, 042336] Published Tue Apr 28, 2015

Description: Author(s): Pierre Wendenbaum, Thierry Platini, and Dragi Karevski We study entanglement creation between two independent XX chains, which are repeatedly coupled locally to spin-1/2 Bell pairs. We show analytically that in the steady state the entanglement of the Bell pairs is perfectly transferred to the chains, generating large-scale interchain pair correlations.... [Phys. Rev. A 91, 040303] Published Mon Apr 27, 2015

Description: Author(s): Courtney G. Brell We propose a generalization of the color codes based on finite groups G . For non-Abelian groups, the resulting model supports non-Abelian anyonic quasiparticles and topological order. We examine the properties of these models such as their relationship to Kitaev quantum double models, quasiparticle ... [Phys. Rev. A 91, 042333] Published Mon Apr 27, 2015

Description: Author(s): Ruben S. Andrist, James R. Wootton, and Helmut G. Katzgraber Current approaches for building quantum computing devices focus on two-level quantum systems which nicely mimic the concept of a classical bit, albeit enhanced with additional quantum properties. However, rather than artificially limiting the number of states to two, the use of d -level quantum syste... [Phys. Rev. A 91, 042331] Published Fri Apr 24, 2015