
Quantum Correlations in Nonlocal Boson Sampling Phys. Rev. Lett. (IF 8.462) Pub Date : 20170919
Farid Shahandeh, Austin P. Lund, and Timothy C. RalphDetermination of the quantum nature of correlations between two spatially separated systems plays a crucial role in quantum information science. Of particular interest is the questions of if and how these correlations enable quantum information protocols to be more powerful. Here, we report on a distributed quantum computation protocol in which the input and output quantum states are considered to be classically correlated in quantum informatics. Nevertheless, we show that the correlations between the outcomes of the measurements on the output state cannot be efficiently simulated using classical algorithms. Crucially, at the same time, local measurement outcomes can be efficiently simulated on classical computers. We show that the only known classicality criterion violated by the input and output states in our protocol is the one used in quantum optics, namely, phasespace nonclassicality. As a result, we argue that the global phasespace nonclassicality inherent within the output state of our protocol represents true quantum correlations.

Dark Matter Coannihilation with a Lighter Species Phys. Rev. Lett. (IF 8.462) Pub Date : 20170919
Asher BerlinWe propose a new thermal freezeout mechanism for ultraheavy dark matter. Dark matter coannihilates with a lighter unstable species that is nearby in mass, leading to an annihilation rate that is exponentially enhanced relative to standard weakly interactive massive particles. This scenario destabilizes any potential dark matter candidate. In order to remain consistent with astrophysical observations, our proposal necessitates very longlived states, motivating striking phenomenology associated with the late decays of ultraheavy dark matter, potentially as massive as the scale of grand unified theories, MGUT∼1016 GeV.

Characterization of theHo163Electron Capture Spectrum: A Step Towards the Electron Neutrino Mass Determination Phys. Rev. Lett. (IF 8.462) Pub Date : 20170919
P. C.O. Ranitzsch, C. Hassel, M. Wegner, D. Hengstler, S. Kempf, A. Fleischmann, C. Enss, L. Gastaldo, A. Herlert, and K. JohnstonThe isotope Ho163 is in many ways the best candidate to perform experiments to investigate the value of the electron neutrino mass. It undergoes an electron capture process to Dy163 with an energy available to the decay, QEC, of about 2.8 keV. According to the present knowledge, this is the lowest QEC value for such transitions. Here we discuss a newly obtained spectrum of Ho163, taken by cryogenic metallic magnetic calorimeters with Ho163 implanted in the absorbers and operated in anticoincident mode for background reduction. For the first time, the atomic deexcitation of the Dy163 daughter atom following the capture of electrons from the 5s shell in Ho163, the OI line, was observed with a calorimetric measurement. The peak energy is determined to be 48 eV. In addition, a precise determination of the energy available for the decay QEC=(2.858±0.010stat±0.05syst) keV was obtained by analyzing the intensities of the lines in the spectrum. This value is in good agreement with the measurement of the mass difference between Ho163 and Dy163 obtained by Penningtrap mass spectrometry, demonstrating the reliability of the calorimetric technique.

Simultaneous Deep Tunneling and Classical Hopping for Hydrogen Diffusion on Metals Phys. Rev. Lett. (IF 8.462) Pub Date : 20170919
Wei Fang, Jeremy O. Richardson, Ji Chen, XinZheng Li, and Angelos MichaelidesHydrogen diffusion on metals exhibits rich quantum behavior, which is not yet fully understood. Using simulations, we show that many hydrogen diffusion barriers can be categorized into those with parabolic tops and those with broad tops. With parabolictop barriers, hydrogen diffusion evolves gradually from classical hopping, to shallow tunneling, to deep tunneling as the temperature (T) decreases, and noticeable quantum effects persist at moderate T. In contrast, with broadtop barriers quantum effects become important only at low T and the classicaltoquantum transition is sharp, at which classical hopping and deep tunneling both occur. This coexistence indicates that more than one mechanism contributes to the quantum reaction rate. The conventional definition of the classicaltoquantum crossover T is invalid for the broad tops, and we give a new definition. Extending this, we propose a model to predict the transition T for broadtop diffusion, providing a general guide for theory and experiment.

Gaussian Hypothesis Testing and Quantum Illumination Phys. Rev. Lett. (IF 8.462) Pub Date : 20170918
Mark M. Wilde, Marco Tomamichel, Seth Lloyd, and Mario BertaQuantum hypothesis testing is one of the most basic tasks in quantum information theory and has fundamental links with quantum communication and estimation theory. In this paper, we establish a formula that characterizes the decay rate of the minimal typeII error probability in a quantum hypothesis test of two Gaussian states given a fixed constraint on the typeI error probability. This formula is a direct function of the mean vectors and covariance matrices of the quantum Gaussian states in question. We give an application to quantum illumination, which is the task of determining whether there is a lowreflectivity object embedded in a target region with a bright thermalnoise bath. For the asymmetricerror setting, we find that a quantum illumination transmitter can achieve an error probability exponent stronger than a coherentstate transmitter of the same mean photon number, and furthermore, that it requires far fewer trials to do so. This occurs when the background thermal noise is either low or bright, which means that a quantum advantage is even easier to witness than in the symmetricerror setting because it occurs for a larger range of parameters. Going forward from here, we expect our formula to have applications in settings well beyond those considered in this paper, especially to quantum communication tasks involving quantum Gaussian channels.

Role of Intrapulse Coherence in CarrierEnvelope Phase Stabilization Phys. Rev. Lett. (IF 8.462) Pub Date : 20170918
Nils Raabe, Tianli Feng, Tobias Witting, Ayhan Demircan, Carsten Brée, and Günter SteinmeyerThe concept of coherence is of fundamental importance for describing the physical characteristics of light and for evaluating the suitability for experimental application. In the case of pulsed laser sources, the pulsetopulse coherence is usually considered for a judgment of the compressibility of the pulse train. This type of coherence is often lost during propagation through a highly nonlinear medium, and pulses prove incompressible despite multioctave spectral coverage. Notwithstanding the apparent loss of interpulse coherence, however, supercontinua enable applications in precision frequency metrology that rely on coherence between different spectral components within a laser pulse. To judge the suitability of a light source for the latter application, we define an alternative criterion, which we term intrapulse coherence. This definition plays a limiting role in the carrierenvelope phase measurement and stabilization of ultrashort pulses. It is shown by numerical simulation and further corroborated by experimental data that filamentationbased supercontinuum generation may lead to a loss of intrapulse coherence despite nearperfect compressibility of the pulse train. This loss of coherence may severely limit active and passive carrierenvelope phase stabilization schemes and applications in optical highfield physics.

Mechanism behind Erosive Bursts In Porous Media Phys. Rev. Lett. (IF 8.462) Pub Date : 20170918
R. Jäger, M. Mendoza, and H. J. HerrmannErosion and deposition during flow through porous media can lead to large erosive bursts that manifest as jumps in permeability and pressure loss. Here we reveal that the cause of these bursts is the reopening of clogged pores when the pressure difference between two opposite sites of the pore surpasses a certain threshold. We perform numerical simulations of flow through porous media and compare our predictions to experimental results, recovering with excellent agreement shape and powerlaw distribution of pressure loss jumps, and the behavior of the permeability jumps as a function of particle concentration. Furthermore, we find that erosive bursts only occur for pressure gradient thresholds within the range of two critical values, independent of how the flow is driven. Our findings provide a better understanding of sudden sand production in oil wells and breakthrough in filtration.

Enhanced SecondOrder Nonlinearity for THz Generation by Resonant Interaction of ExcitonPolariton Rabi Oscillations with Optical Phonons Phys. Rev. Lett. (IF 8.462) Pub Date : 20170918
Katharina Rojan, Yoan Léger, Giovanna Morigi, Maxime Richard, and Anna MinguzziSemiconductor microcavities in the strongcoupling regime exhibit an energy scale in the terahertz (THz) frequency range, which is fixed by the Rabi splitting between the upper and lower excitonpolariton states. While this range can be tuned by several orders of magnitude using different excitonic media, the transition between both polaritonic states is dipole forbidden. In this work, we show that, in cadmium telluride microcavities, the Rabioscillationdriven THz radiation is actually active without the need for any change in the microcavity design. This feature results from the unique resonance condition which is achieved between the Rabi splitting and the phononpolariton states and leads to a giant enhancement of the secondorder nonlinearity.

Search for Low Mass Vector Resonances Decaying to QuarkAntiquark Pairs in ProtonProton Collisions ats=13TeV Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
A. M. Sirunyanet al.(CMS Collaboration)A search is reported for a narrow vector resonance decaying to quarkantiquark pairs in protonproton collisions at s = 13 TeV , collected with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 2.7 fb − 1 . The vector resonance is produced at large transverse momenta, with its decay products merged into a single jet. The resulting signature is a peak over background in the distribution of the invariant mass of the jet. The results are interpreted in the framework of a leptophobic vector resonance and no evidence is found for such particles in the mass range of 100–300 GeV. Upper limits at 95% confidence level on the production cross section are presented in a region of masscoupling phase space previously unexplored at the LHC. The region below 140 GeV has not been explored by any previous experiments.

Dissecting Reactor Antineutrino Flux Calculations Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
A. A. Sonzogni, E. A. McCutchan, and A. C. HayesCurrent predictions for the antineutrino yield and spectra from a nuclear reactor rely on the experimental electron spectra from U 235 , Pu 239 , Pu 241 and a numerical method to convert these aggregate electron spectra into their corresponding antineutrino ones. In the present work we investigate quantitatively some of the basic assumptions and approximations used in the conversion method, studying first the compatibility between two recent approaches for calculating electron and antineutrino spectra. We then explore different possibilities for the disagreement between the measured Daya Bay and the HuberMueller antineutrino spectra, including the U 238 contribution as well as the effective charge and the allowed shape assumption used in the conversion method. We observe that including a shape correction of about + 6 % MeV − 1 in conversion calculations can better describe the Daya Bay spectrum. Because of a lack of experimental data, this correction cannot be ruled out, concluding that in order to confirm the existence of the reactor neutrino anomaly, or even quantify it, precisely measured electron spectra for about 50 relevant fission products are needed. With the advent of new rare ion facilities, the measurement of shape factors for these nuclides, for many of which precise beta intensity data from TAGS experiments already exist, would be highly desirable.

Enhancement of the Triple Alpha Rate in a Hot Dense Medium Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
Mary Beard, Sam M. Austin, and Richard CyburtIn a sufficiently hot and dense astrophysical environment the rate of the triplealpha ( 3 α ) reaction can increase greatly over the value appropriate for helium burning stars owing to hadronically induced deexcitation of the Hoyle state. In this Letter we use a statistical model to evaluate the enhancement as a function of temperature and density. For a density of 10 6 g cm − 3 enhancements can exceed a factor of 100. In high temperature or density situations, the enhanced 3 α rate is a better estimate of this rate and should be used in these circumstances. We then examine the effect of these enhancements on production of C 12 in the neutrino wind following a supernova explosion and in an xray burster.

Atomic Clock Measurements of Quantum Scattering Phase Shifts Spanning Feshbach Resonances at Ultralow Fields Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
Aaron Bennett, Kurt Gibble, Servaas Kokkelmans, and Jeremy M. HutsonWe use an atomic fountain clock to measure quantum scattering phase shifts precisely through a series of narrow, lowfield Feshbach resonances at average collision energies below 1 μ K . Our low spread in collision energy yields phase variations of order ± π / 2 for target atoms in several F , m F states. We compare them to a theoretical model and establish the accuracy of the measurements and the theoretical uncertainties from the fitted potential. We find overall excellent agreement, with small statistically significant differences that remain unexplained.

Vibrational Feshbach Resonances Mediated by Nondipole PositronMolecule Interactions Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
M. R. Natisin, J. R. Danielson, G. F. Gribakin, A. R. Swann, and C. M. SurkoMeasurements of energyresolved positronmolecule annihilation show the existence of positron binding and vibrational Feshbach resonances. The existing theory describes this phenomenon successfully for the case of infraredactive vibrational modes that allow dipole coupling between the incident positron and the vibrational motion. Presented here are measurements of positronmolecule annihilation made using a recently developed cryogenic positron beam capable of significantly improved energy resolution. The results provide evidence of resonances associated with infraredinactive vibrational modes, indicating that positronmolecule bound states may be populated by nondipole interactions. The anticipated ingredients for a theoretical description of such interactions are discussed.

Emergence of TypeII Dirac Points in Graphynelike Photonic Lattices Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
Georgios G. Pyrialakos, Nicholas S. Nye, Nikolaos V. Kantartzis, and Demetrios N. Christodoulides 
Spontaneous Formation of Vector Vortex Beams in VerticalCavity SurfaceEmitting Lasers with Feedback Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
Jesus JimenezGarcia, Pedro Rodriguez, T. Guillet, and T. Ackemann 
Optically Controlled Orbital Angular Momentum Generation in a Polaritonic Quantum Fluid Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
S. M. H. Luk, N. H. Kwong, P. Lewandowski, S. Schumacher, and R. BinderApplications of the orbital angular momentum (OAM) of light range from the next generation of optical communication systems to optical imaging and optical manipulation of particles. Here we propose a micronsized semiconductor source that emits light with predefined OAM pairs. This source is based on a polaritonic quantum fluid. We show how in this system modulational instabilities can be controlled and harnessed for the spontaneous formation of OAM pairs not present in the pump laser source. Once created, the OAM states exhibit exotic flow patterns in the quantum fluid, characterized by generationannihilation pairs. These can only occur in open systems, not in equilibrium condensates, in contrast to wellestablished vortexantivortex pairs.

TwoDimensional Pulse Propagation without Anomalous Dispersion Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
Carl M. Bender, Francisco J. RodríguezFortuño, Sarben Sarkar, and Anatoly V. ZayatsAnomalous dispersion is a surprising phenomenon associated with wave propagation in an even number of space dimensions. In particular, wave pulses propagating in twodimensional space change shape and develop a tail even in the absence of a dispersive medium. We show mathematically that this dispersion can be eliminated by considering a modified wave equation with two geometric spatial dimensions and, unconventionally, two timelike dimensions. Experimentally, such a wave equation describes pulse propagation in an optical or acoustic medium with hyperbolic dispersion, leading to a fundamental understanding and new approaches to ultrashort pulse shaping in nanostructured metamaterials.

Shapes and Fissility of Highly Charged and Rapidly Rotating Levitated Liquid Drops Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
L. Liao and R. J. A. HillWe use diamagnetic levitation to investigate the shapes and the stability of free electrically charged and spinning liquid drops of volume ∼ 1 ml. In addition to binary fission and Taylor conejet fission modes observed at low and high charge density, respectively, we also observe an unusual mode which appears to be a hybrid of the two. Measurements of the angular momentum required to fission a charged drop show that nonrotating drops become unstable to fission at the amount of charge predicted by Lord Rayleigh. This result is in contrast to the observations of most previous experiments on fissioning charged drops, which typically exhibit fission well below Rayleigh’s limit.

Extraordinary Indentation Strain Stiffening Produces Superhard Tungsten Nitrides Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
Cheng Lu, Quan Li, Yanming Ma, and Changfeng ChenTransitionmetal lightelement compounds are a class of designer materials tailored to be a new generation of superhard solids, but indentation strain softening has hitherto limited their intrinsic loadinvariant hardness to well below the 40 GPa threshold commonly set for superhard materials. Here we report findings from firstprinciples calculations that two tungsten nitrides, hP4WN and hP 6 − WN 2 , exhibit extraordinary strain stiffening that produces remarkably enhanced indentation strengths exceeding 40 GPa, raising exciting prospects of realizing the longsought nontraditional superhard solids. Calculations show that hP4WN is metallic both at equilibrium and under indentation, marking it as the first known intrinsic superhard metal. An xray diffraction pattern analysis indicates the presence of hP4WN in a recently synthesized specimen. We elucidate the intricate bonding and stress response mechanisms for the identified structural strengthening, and the insights may help advance rational design and discovery of additional novel superhard materials.

Mapping Isobaric Aging onto the Equilibrium Phase Diagram Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
Kristine NissThe linear volume relaxation and the nonlinear volume aging of a glassforming liquid are measured, directly compared, and used to extract the outofequilibrium relaxation time. This opens a window to investigate how the relaxation time depends on temperature, structure, and volume in parts of phase space that are not accessed by the equilibrium liquid. It is found that the temperature dependence of relaxation time is nonArrhenius even in the isostructural case—challenging the AdamGibbs entropy model. Based on the presented data and the idea that aging happens through quasiequilibrium states, we suggest a mapping of the outofequilibrium states during isobaric aging to the equilibrium phase diagram. This mapping implies the existence of isostructural lines in the equilibrium phase diagram. The relaxation time is found to depend on the bath temperature, density, and a just single structural parameter, referred to as an effective temperature.

Echoes of the Glass Transition in Athermal Soft Spheres Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
Peter K. Morse and Eric I. CorwinRecent theoretical advances have led to the creation of a unified phase diagram for the thermal glass and athermal jamming transitions. This diagram makes clear that, while related, the modecoupling—or dynamic—glass transition is distinct from the jamming transition, occurring at a finite temperature and significantly lower density than the jamming transition. Nonetheless, we demonstrate a prejamming transition in athermal frictionless spheres which occurs at the same density as the modecoupling transition and is marked by percolating clusters of locally rigid particles. At this density in both the thermal and athermal systems, individual motions of an extensive number of particles become constrained, such that only collective motion is possible. This transition, which is well below jamming, exactly matches the definition of collective behavior at the dynamical transition of glasses. Thus, we reveal that the genesis of rigidity in both thermal and athermal systems is governed by the same underlying topological transition in their shared configuration space.

Evidence That StrainRate Softening Is Not Necessary for Material Instability Patterns Phys. Rev. Lett. (IF 8.462) Pub Date : 20170915
Julio R. Valdes, François Guillard, and Itai EinavStrainrate softening has been associated with a wide variety of material instabilities, from the Portevin–Le Chatelier effect in metal alloys to stickslip motion in crust faults. Dynamic instability patterns have been recently discovered in brittle porous media: diffused, oscillatory, and erratic compaction. Using model simulations inspired by experiments with puffed rice, we question the link between these dynamic patterns and strainrate sensitivity in such media. An important feature of our model is that it can recover strainrate softening as an emergent phenomenon, without imposing it a priori at its microstructural scale. More importantly, the model also demonstrates that the full range of dynamic patterns can develop without presenting macroscopic strainrate softening. Based on this counterexample model, we therefore argue that strainrate softening should not be taken as a necessary condition for the emergence of instability patterns. Our findings in brittle porous media have implications on models that require strainrate softening to explain earthquake and metal alloy instabilities.

Monogamy Inequality for Any Local Quantum Resource and Entanglement Phys. Rev. Lett. (IF 8.462) Pub Date : 20170914
S. CamaletWe derive a monogamy inequality for any local quantum resource and entanglement. It results from the fact that there is always a convex measure for a quantum resource, as shown here, and from the relation between entanglement and local entropy. One of its consequences is an entanglement monogamy different from that usually discussed. If the local resource is nonuniformity or coherence, it is satisfied by familiar resource and entanglement measures. The ensuing upper bound for the local coherence, determined by the entanglement, is independent of the basis used to define the coherence.

Diffusion in Deterministic Interacting Lattice Systems Phys. Rev. Lett. (IF 8.462) Pub Date : 20170914
Marko Medenjak, Katja Klobas, and Tomaž ProsenWe study reversible deterministic dynamics of classical charged particles on a lattice with hardcore interaction. It is rigorously shown that the system exhibits three types of transport phenomena, ranging from ballistic, through diffusive to insulating. By obtaining an exact expressions for the current timeautocorrelation function we are able to calculate the linear response transport coefficients, such as the diffusion constant and the Drude weight. Additionally, we calculate the longtime charge profile after an inhomogeneous quench and obtain diffusive profilewith the GreenKubo diffusion constant. Exact analytical results are corroborated by Monte Carlo simulations.

Scaling Theory of Entanglement at the ManyBody Localization Transition Phys. Rev. Lett. (IF 8.462) Pub Date : 20170914
Philipp T. Dumitrescu, Romain Vasseur, and Andrew C. PotterWe study the universal properties of eigenstate entanglement entropy across the transition between manybody localized (MBL) and thermal phases. We develop an improved real space renormalization group approach that enables numerical simulation of large system sizes and systematic extrapolation to the infinite system size limit. For systems smaller than the correlation length, the average entanglement follows a subthermal volume law, whose coefficient is a universal scaling function. The full distribution of entanglement follows a universal scaling form, and exhibits a bimodal structure that produces universal subleading powerlaw corrections to the leading volume law. For systems larger than the correlation length, the short interval entanglement exhibits a discontinuous jump at the transition from fully thermal volume law on the thermal side, to pure area law on the MBL side.

Realizing and Detecting a Topological Insulator in the AIII Symmetry Class Phys. Rev. Lett. (IF 8.462) Pub Date : 20170914
Carlos G. Velasco and Belén ParedesTopological insulators in the AIII (chiral unitary) symmetry class lack experimental realization. Moreover, fractionalization in onedimensional topological insulators has not been yet directly observed. Our work might open possibilities for both challenges. We propose a onedimensional model realizing the AIII symmetry class which can be realized in current experiments with ultracold atomic gases. We further report on a distinctive property of topological edge modes in the AIII class: in contrast to those in the wellstudied BDI (chiral orthogonal) class, they have nonzero momentum. Exploiting this feature we propose a path for the detection of fractionalization. A fermion added to an AIII system splits into two halves localized at opposite momenta, which can be detected by imaging the momentum distribution.

Disappearance of the Hexatic Phase in a Binary Mixture of Hard Disks Phys. Rev. Lett. (IF 8.462) Pub Date : 20170914
John Russo and Nigel B. WildingRecent studies of melting in hard disks have confirmed the existence of a hexatic phase occurring in a narrow window of density which is separated from the isotropic liquid phase by a firstorder transition, and from the solid phase by a continuous transition. However, little is known concerning the melting scenario in mixtures of hard disks. Here we employ tailored Monte Carlo simulations to elucidate the phase behavior of a system of large ( l ) and small ( s ) disks with diameter ratio σ l / σ s = 1.4 . We find that as small disks are introduced to a system of large ones, the stability window of the hexatic phase shrinks progressively until the line of continuous transitions terminates at an end point beyond which melting becomes a firstorder liquidsolid transition. This occurs at surprisingly low concentrations of the small disks, c ≲ 1 % , emphasizing the fragility of the hexatic phase. We speculate that the change to the melting scenario is a consequence of strong fractionation effects, the nature of which we elucidate.

Temperature Scaling Law for Quantum Annealing Optimizers Phys. Rev. Lett. (IF 8.462) Pub Date : 20170914
Tameem Albash, Victor MartinMayor, and Itay Hen 
Heat Transport via LowDimensional Systems with Broken TimeReversal Symmetry Phys. Rev. Lett. (IF 8.462) Pub Date : 20170914
Shuji Tamaki, Makiko Sasada, and Keiji SaitoWe consider heat transport via systems with broken timereversal symmetry. We apply magnetic fields to the onedimensional charged particle systems with transverse motions. The standard momentum conservation is not satisfied. To focus on this effect clearly, we introduce a solvable model. We exactly demonstrate that the anomalous transport with a new exponent can appear. We numerically show the violation of the standard relation between the powerlaw decay in the equilibrium correlation and the diverging exponent of the thermal conductivity in the open system.

Constraining Quirky Tracks with Conventional Searches Phys. Rev. Lett. (IF 8.462) Pub Date : 20170914
Marco Farina and Matthew LowQuirks are particles that are charged both under the standard model and under a new confining group. The quirk setup assumes there are no light flavors of the new confining group, so that while the theory is in a confining phase, the quirkantiquirk distance can be macroscopic. In this Letter, we reinterpret existing collider limits, those from monojet and heavy stable charged particle searches, as limits on quirks. Additionally, we propose a new search in the magneticfieldless CMS data for quirks and estimate the sensitivity. We focus on the region where the confinement scale is roughly between 1 and 100 eV and find mass constraints in the TeV range, depending on the quirk’s quantum numbers.

Incommensurate Chirality Density Wave Transition in a Hybrid Molecular Framework Phys. Rev. Lett. (IF 8.462) Pub Date : 20170914
Joshua A. Hill, Kirsten E. Christensen, and Andrew L. GoodwinUsing singlecrystal xray diffraction we characterize the 235 K incommensurate phase transition in the hybrid molecular framework tetraethylammonium silver(I) dicyanoargentate, [ NEt 4 ] Ag 3 ( CN ) 4 . We demonstrate the transition to involve spontaneous resolution of chiral [ NEt 4 ] + conformations, giving rise to a state in which molecular chirality is incommensurately modulated throughout the crystal lattice. We refer to this state as an incommensurate chirality density wave (XDW) phase, which represents a fundamentally new type of chiral symmetry breaking in the solid state. Drawing on parallels to the incommensurate ferroelectric transition of NaNO 2 , we suggest the XDW state arises through coupling between acoustic (shear) and molecular rotoinversion modes. Such coupling is symmetry forbidden at the Brillouin zone center but symmetry allowed for small but finite modulation vectors q = [ 0 , 0 , q z ] * . The importance of longwavelength chirality modulations in the physics of this hybrid framework may have implications for the generation of mesoscale chiral textures, as required for advanced photonic materials.

SelfAveraging Fluctuations in the Chaoticity of Simple Fluids Phys. Rev. Lett. (IF 8.462) Pub Date : 20170914
Moupriya Das and Jason R. GreenBulk properties of equilibrium liquids are a manifestation of intermolecular forces. Here, we show how these forces imprint on dynamical fluctuations in the Lyapunov exponents for simple fluids with and without attractive forces. While the bulk of the spectrum is strongly selfaveraging, the first Lyapunov exponent selfaverages only weakly and at a rate that depends on the length scale of the intermolecular forces; shortrange repulsive forces quantitatively dominate longerrange attractive forces, which act as a weak perturbation that slows the convergence to the thermodynamic limit. Regardless of intermolecular forces, the fluctuations in the KolmogorovSinai entropy rate diverge, as one expects for an extensive quantity, and the spontaneous fluctuations of these dynamical observables obey fluctuationdissipationlike relationships. Together, these results are a representation of the van der Waals picture of fluids and another lens through which we can view the liquid state.

Nanoparticle Superlattices as QuasiFrankKasper Phases Phys. Rev. Lett. (IF 8.462) Pub Date : 20170914
Alex TravessetI show that all phases reported experimentally in binary nanoparticle superlattices can be described as networks of disclinations in an ideal lattice of regular tetrahedra. A set of simple rules is provided to identify the different disclination types from the Voronoi construction, and it is shown that those disclinations completely screen the positive curvature of the ideal tetrahedral lattice. In this way, this study provides a generalization of the wellknown FrankKasper phases to binary systems consisting of two types of particles, and with a more general type of disclinations, i.e., quasiFrankKasper phases. The study comprises all strategies in nanoparticle selfassembly, whether driven by DNA or hydrocarbon ligands, and establishes the universal tendency of superlattices to develop icosahedral order, which is facilitated by the asymmetry of the particles. Besides its interest in predicting nanoparticle selfassembly, I discuss the implications for models of the glass transition, micelles of diblock polymers, and dendritic molecules, among many others.

Correlation Decay in Fermionic Lattice Systems with PowerLaw Interactions at Nonzero Temperature Phys. Rev. Lett. (IF 8.462) Pub Date : 20170913
Senaida HernándezSantana, Christian Gogolin, J. Ignacio Cirac, and Antonio AcínWe study correlations in fermionic lattice systems with longrange interactions in thermal equilibrium. We prove a bound on the correlation decay between anticommuting operators and generalize a longrange LiebRobinsontype bound. Our results show that in these systems of spatial dimension D with, not necessarily translation invariant, twosite interactions decaying algebraically with the distance with an exponent α ≥ 2 D , correlations between such operators decay at least algebraically to 0 with an exponent arbitrarily close to α at any nonzero temperature. Our bound is asymptotically tight, which we demonstrate by a high temperature expansion and by numerically analyzing densitydensity correlations in the onedimensional quadratic (free, exactly solvable) Kitaev chain with longrange pairing.

SelfInteracting Dark Matter Can Explain Diverse Galactic Rotation Curves Phys. Rev. Lett. (IF 8.462) Pub Date : 20170913
Ayuki Kamada, Manoj Kaplinghat, Andrew B. Pace, and HaiBo Yu 
GaussBonnet Supergravity in Six Dimensions Phys. Rev. Lett. (IF 8.462) Pub Date : 20170913
Joseph Novak, Mehmet Ozkan, Yi Pang, and Gabriele TartaglinoMazzucchelliThe supersymmetrization of curvature squared terms is important in the study of the lowenergy limit of compactified superstrings where a distinguished role is played by the GaussBonnet combination, which is ghostfree. In this Letter, we construct its offshell N = ( 1 , 0 ) supersymmetrization in six dimensions for the first time. By studying this invariant together with the supersymmetric EinsteinHilbert term, we confirm and extend known results of the α ′ corrected string theory compactified to six dimensions. Finally, we analyze the spectrum about the AdS 3 × S 3 solution.

Derivation of the TimeReversal Anomaly for (2+1)Dimensional Topological Phases Phys. Rev. Lett. (IF 8.462) Pub Date : 20170913
Yuji Tachikawa and Kazuya YonekuraWe prove an explicit formula conjectured recently by Wang and Levin for the anomaly of timereversal symmetry in ( 2 + 1 )dimensional fermionic topological quantum field theories. The crucial step is to determine the crosscap state in terms of the modular S matrix and T 2 eigenvalues, generalizing the recent analysis by Barkeshli et al. in the bosonic case.

Unexpected Large Hole Effective Masses in SnSe Revealed by AngleResolved Photoemission Spectroscopy Phys. Rev. Lett. (IF 8.462) Pub Date : 20170913
Qiangsheng Lu, Minghui Wu, Di Wu, Cheng Chang, YanPing Guo, ChunSheng Zhou, Wei Li, XiaoMing Ma, Gan Wang, LiDong Zhao, Li Huang, Chang Liu, and Jiaqing HeSnSe has emerged as an efficient thermoelectric material since a high value of the thermoelectric figure of merit ( Z T ) has been reported recently. Here we show with systematic angle resolved photoemission spectroscopy data that the lowlying electronic structures of undoped and holedoped SnSe crystals exhibit noticeable temperature variation from 80 to 600 K. In particular, the hole effective masses for the two lowest lying valence band maxima are found to be very large and increase with decreasing temperature. Thermoelectric parameters derived from such holemass enhancement agree well with the transport values, indicating comprehensively a reduced impact of multivalley transport to the system’s thermoelectric performance.

Large Spin Perturbation Theory for Conformal Field Theories Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
Luis F. AldayWe consider conformal field theories around points of large twist degeneracy. Examples of this are theories with weakly broken higher spin symmetry and perturbations around generalized free fields. At the degenerate point we introduce twist conformal blocks. These are eigenfunctions of certain quartic operators and encode the contribution, to a given fourpoint correlator, of the whole tower of intermediate operators with a given twist. As we perturb around the degenerate point, the twist degeneracy is lifted. In many situations this breaking is controlled by inverse powers of the spin. In such cases the twist conformal blocks can be decomposed into a sequence of functions which we systematically construct. Decomposing the fourpoint correlator in this basis turns crossing symmetry into an algebraic problem. Our method can be applied to a wide spectrum of conformal field theories in any number of dimensions and at any order in the breaking parameter. As an example, we compute the spectrum of various theories around generalized free fields.

Induced Cavities for Photonic Quantum Gates Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
Ohr Lahad and Ofer FirstenbergEffective cavities can be optically induced in atomic media and employed to strengthen optical nonlinearities. Here we study the integration of induced cavities with a photonic quantum gate based on Rydberg blockade. Accounting for loss in the atomic medium, we calculate the corresponding finesse and gate infidelity. Our analysis shows that the conventional limits imposed by the blockade optical depth are mitigated by the induced cavity in long media, thus establishing the total optical depth of the medium as a complementary resource.

Conductance and Kondo Interference beyond Proportional Coupling Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
Luis G. G. V. Dias da Silva, Caio H. Lewenkopf, Edson Vernek, Gerson J. Ferreira, and Sergio E. UlloaThe transport properties of nanostructured systems are deeply affected by the geometry of the effective connections to metallic leads. In this work we derive a conductance expression for a class of interacting systems whose connectivity geometries do not meet the MeirWingreen proportional coupling condition. As an interesting application, we consider a quantum dot connected coherently to tunable electronic cavity modes. The structure is shown to exhibit a welldefined Kondo effect over a wide range of coupling strengths between the two subsystems. In agreement with recent experimental results, the calculated conductance curves exhibit strong modulations and asymmetric behavior as different cavity modes are swept through the Fermi level. These conductance modulations occur, however, while maintaining robust Kondo singlet correlations of the dot with the electronic reservoir, a direct consequence of the lopsided nature of the device.

Quantum Criticality in Resonant Andreev Conduction Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
M. Pustilnik, B. van Heck, R. M. Lutchyn, and L. I. GlazmanMotivated by recent experiments with proximitized nanowires, we study a mesoscopic swave superconductor connected via point contacts to normalstate leads. We demonstrate that at energies below the charging energy the system is described by the twochannel Kondo model, which can be brought to the quantum critical regime by varying the gate potential and conductances of the contacts.

Mechanisms for Strong Anisotropy of InPlanegFactors in Hole Based Quantum Point Contacts Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
D. S. Miserev, A. Srinivasan, O. A. Tkachenko, V. A. Tkachenko, I. Farrer, D. A. Ritchie, A. R. Hamilton, and O. P. SushkovInplane hole g factors measured in quantum point contacts based on ptype heterostructures strongly depend on the orientation of the magnetic field with respect to the electric current. This effect, first reported a decade ago and confirmed in a number of publications, has remained an open problem. In this work, we present systematic experimental studies to disentangle different mechanisms contributing to the effect and develop the theory which describes it successfully. We show that there is a new mechanism for the anisotropy related to the existence of an additional B+k−4σ+ effective Zeeman interaction for holes, which is kinematically different from the standard single Zeeman term B−k−2σ+ considered until now.

Emergent BerezinskiiKosterlitzThouless Phase in LowDimensional Ferroelectrics Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
Y. Nahas, S. Prokhorenko, I. Kornev, and L. BellaicheUsing firstprinciplesbased simulations merging an effective Hamiltonian scheme with scaling, symmetry, and topological arguments, we find that an overlooked BerezinskiiKosterlitzThouless (BKT) phase sustained by quasicontinuous symmetry emerges between the ferroelectric phase and the paraelectric one of BaTiO3 ultrathin film, being under tensile strain. Not only do these results provide an extension of BKT physics to the field of ferroelectrics, but they also unveil their nontrivial critical behavior in low dimensions.

ShearInduced Heterogeneity in Associating Polymer Gels: Role of Network Structure and Dilatancy Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
Ahmad K. Omar and ZhenGang WangWe study associating polymer gels under steady shear using Brownian dynamics simulation to explore the interplay between the network structure, dynamics, and rheology. For a wide range of flow rates, we observe the formation of shear bands with a pronounced difference in shear rate, concentration, and structure. A striking increase in the polymer pressure in the gradient direction with shear, along with the inherently large compressibility of the gels, is shown to be a crucial factor in destabilizing homogeneous flow through sheargradient concentration coupling. We find that shear has only a modest influence on the degree of association, but induces marked spatial heterogeneity in the network connectivity. We attribute the increase in the polymer pressure (and polymer mobility) to this structural reorganization.

Dynamical Scaling and Phase Coexistence in Topologically Constrained DNA Melting Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
Y. A. G. Fosado, D. Michieletto, and D. MarenduzzoThere is a longstanding experimental observation that the melting of topologically constrained DNA, such as circular closed plasmids, is less abrupt than that of linear molecules. This finding points to an important role of topology in the physics of DNA denaturation, which is, however, poorly understood. Here, we shed light on this issue by combining largescale Brownian dynamics simulations with an analytically solvable phenomenological Landau mean field theory. We find that the competition between melting and supercoiling leads to phase coexistence of denatured and intact phases at the singlemolecule level. This coexistence occurs in a wide temperature range, thereby accounting for the broadening of the transition. Finally, our simulations show an intriguing topologydependent scaling law governing the growth of denaturation bubbles in supercoiled plasmids, which can be understood within the proposed mean field theory.

Erratum: Reduced Limit on the Permanent Electric Dipole Moment ofHg199[Phys. Rev. Lett.116, 161601 (2016)] Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
B. Graner, Y. Chen, E. G. Lindahl, and B. R. HeckelDOI:https://doi.org/10.1103/PhysRevLett.119.119901

Improved Noninterferometric Test of Collapse Models Using Ultracold Cantilevers Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
A. Vinante, R. Mezzena, P. Falferi, M. Carlesso, and A. Bassi 
All Entangled States can Demonstrate Nonclassical Teleportation Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
Daniel Cavalcanti, Paul Skrzypczyk, and Ivan Šupić 
Gravitational Wave Oscillations in Bigravity Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
Kevin Max, Moritz Platscher, and Juri SmirnovWe derive consistent equations for gravitational wave oscillations in bigravity. In this framework a second dynamical tensor field is introduced in addition to general relativity and coupled such that one massless and one massive linear combination arise. Only one of the two tensors is the physical metric coupling to matter, and thus the basis in which gravitational waves propagate is different from the basis where the wave is produced and detected. Therefore, one should expect—in analogy to neutrino oscillations—to observe an oscillatory behavior. We show for the first time how this behavior arises explicitly, discuss phenomenological implications, and present new limits on the graviton parameter space in bigravity.

First Measurement of TransverseSpinDependent Azimuthal Asymmetries in the DrellYan Process Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
M. Aghasyanet al.(COMPASS Collaboration)The first measurement of transversespindependent azimuthal asymmetries in the pioninduced DrellYan (DY) process is reported. We use the CERN SPS 190 GeV/c π− beam and a transversely polarized ammonia target. Three azimuthal asymmetries giving access to different transversemomentumdependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3 GeV/c2 and 8.5 GeV/c2. Within the experimental uncertainties, the observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of quantum chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semiinclusive deepinelastic scattering (SIDIS) data. We present two other asymmetries originating from the pion BoerMulders TMD PDFs convoluted with either the nucleon transversity or pretzelosity TMD PDFs. A recent COMPASS SIDIS measurement was obtained at a hard scale comparable to that of these DY results. This opens the way for possible tests of fundamental QCD universality predictions.

Probing the Hardest Branching within Jets in HeavyIon Collisions Phys. Rev. Lett. (IF 8.462) Pub Date : 20170912
YangTing Chien and Ivan VitevHeavy ion collisions present exciting opportunities to study the effects of quantum coherence in the formation of subatomic particle showers. We report on the first calculation of the momentum sharing and angular separation distributions between the leading subjets inside a reconstructed jet in such collisions. These observables are directly sensitive to the hardest branching within jets and can probe the early stage of the jet formation. We find that the leadingorder mediuminduced splitting functions, here obtained in the framework of softcollinear effective theory with Glauber gluon interactions, capture the essential manybody physics, which is different from protonproton reactions. Qualitative and in most cases quantitative agreement between theory and preliminary CMS measurements suggests that hard parton branching in strongly interacting matter can be dramatically modified. We also propose a new measurement that will illuminate its angular structure.

Diffusion and Signatures of Localization in Stochastic Conformal Field Theory Phys. Rev. Lett. (IF 8.462) Pub Date : 20170911
Denis Bernard and Benjamin DoyonWe define a simple model of conformal field theory in random spacetime environments, which we refer to as stochastic conformal field theory. This model accounts for the effects of dilute random impurities in strongly interacting critical manybody systems. On one hand, surprisingly, although impurities are separated by macroscopic distances, we find that the infinitetime steady state is factorized on microscopic lengths, a signature of the emergence of localization. The stationary state also displays vanishing energy current and strong uncorrelated spatial fluctuations of local observables. On the other hand, at finite times, the transient shows a crossover from ballistic to diffusive energy propagation. In this regime and a Markovian limit, concentrating on currentgenerating initial states with a temperature imbalance, we show that the energy current and density satisfy simple dissipative hydrodynamic equations. We describe the spacetime scales at which nonequilibrium currents exist. We show that a lightcone effect subsists in the presence of impurities although a momentum burst propagates transiently on a diffusive scale only.

Observation of the Doubly Charmed BaryonΞcc++ Phys. Rev. Lett. (IF 8.462) Pub Date : 20170911
R. Aaijet al.(LHCb Collaboration) 
Enhancement of the Upper Critical Field in Disordered Transition Metal Dichalcogenide Monolayers Phys. Rev. Lett. (IF 8.462) Pub Date : 20170911
Stefan Ilić, Julia S. Meyer, and Manuel HouzetWe calculate the effect of impurities on the superconducting phase diagram of transition metal dichalcogenide monolayers in the presence of an inplane magnetic field. Because of strong intrinsic spinorbit coupling, the upper critical field greatly surpasses the Pauli limit at low temperatures. We find that it is insensitive to intravalley scattering and, ultimately, limited by intervalley scattering.

Electric Double Layer Composed of an Antagonistic Salt in an Aqueous Mixture: Local Charge Separation and Surface Phase Transition Phys. Rev. Lett. (IF 8.462) Pub Date : 20170911
Shunsuke Yabunaka and Akira OnukiWe examine an electric double layer containing an antagonistic salt in an aqueous mixture, where the cations are small and hydrophilic but the anions are large and hydrophobic. In this situation, a strong coupling arises between the charge density and the solvent composition. As a result, the anions are trapped in an oilrich adsorption layer on a hydrophobic wall. We then vary the surface charge density σ on the wall. For σ > 0 the anions remain accumulated, but for σ < 0 the cations are attracted to the wall with increasing  σ  . Furthermore, the electric potential drop Ψ ( σ ) is nonmonotonic when the solvent interaction parameter χ ( T ) exceeds a critical value χ c determined by the composition and the ion density in the bulk. This leads to a firstorder phase transition between two kinds of electric double layers with different σ and common Ψ . In equilibrium such twolayer regions can coexist. The steric effect due to finite ion sizes is crucial in these phenomena.

General Galilei Covariant Gaussian Maps Phys. Rev. Lett. (IF 8.462) Pub Date : 20170908
Giulio Gasbarri, Marko Toroš, and Angelo BassiWe characterize general nonMarkovian Gaussian maps which are covariant under Galilean transformations. In particular, we consider translational and Galilean covariant maps and show that they reduce to the known Holevo result in the Markovian limit. We apply the results to discuss measures of macroscopicity based on classicalization maps, specifically addressing dissipation, Galilean covariance and nonMarkovianity. We further suggest a possible generalization of the macroscopicity measure defined by Nimmrichter and Hornberger [Phys. Rev. Lett. 110, 16 (2013)].

Experimental Detection of Quantum Channel Capacities Phys. Rev. Lett. (IF 8.462) Pub Date : 20170908
Álvaro Cuevas, Massimiliano Proietti, Mario Arnolfo Ciampini, Stefano Duranti, Paolo Mataloni, Massimiliano F. Sacchi, and Chiara MacchiavelloWe present an efficient experimental procedure that certifies nonvanishing quantum capacities for qubit noisy channels. Our method is based on the use of a fixed bipartite entangled state, where the system qubit is sent to the channel input. A particular set of local measurements is performed at the channel output and the ancilla qubit mode, obtaining lower bounds to the quantum capacities for any unknown channel with no need of quantum process tomography. The entangled qubits have a Bell state configuration and are encoded in photon polarization. The lower bounds are found by estimating the Shannon and von Neumann entropies at the output using an optimized basis, whose statistics is obtained by measuring only the three observables σ x ⊗ σ x , σ y ⊗ σ y , and σ z ⊗ σ z .

PolynomialTime Classical Simulation of Quantum Ferromagnets Phys. Rev. Lett. (IF 8.462) Pub Date : 20170908
Sergey Bravyi and David GossetWe consider a family of quantum spin systems which includes, as special cases, the ferromagnetic X Y model and ferromagnetic Ising model on any graph, with or without a transverse magnetic field. We prove that the partition function of any model in this family can be efficiently approximated to a given relative error ε using a classical randomized algorithm with runtime polynomial in ε − 1 , system size, and inverse temperature. As a consequence, we obtain a polynomial time algorithm which approximates the free energy or ground energy to a given additive error. We first show how to approximate the partition function by the perfect matching sum of a finite graph with positive edge weights. Although the perfect matching sum is not known to be efficiently approximable in general, the graphs obtained by our method have a special structure which facilitates efficient approximation via a randomized algorithm due to Jerrum and Sinclair.

Hybrid Semiclassical Theory of Quantum Quenches in OneDimensional Systems Phys. Rev. Lett. (IF 8.462) Pub Date : 20170908
Cătălin Paşcu Moca, Márton Kormos, and Gergely ZarándWe develop a hybrid semiclassical method to study the time evolution of onedimensional quantum systems in and out of equilibrium. Our method handles internal degrees of freedom completely quantum mechanically by a modified timeevolving block decimation method while treating orbital quasiparticle motion classically. We can follow dynamics up to time scales well beyond the reach of standard numerical methods to observe the crossover between preequilibrated and locally phase equilibrated states. As an application, we investigate the quench dynamics and phase fluctuations of a pair of tunnelcoupled onedimensional Bose condensates. We demonstrate the emergence of solitoncollisioninduced phase propagation, solitonentropy production, and multistep thermalization. Our method can be applied to a wide range of gapped onedimensional systems.
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