
Engineered CRISPRCas9 nuclease with expanded targeting space Science (IF 41.058) Pub Date : 20180918
Hiroshi Nishimasu, Xi Shi, Soh Ishiguro, Linyi Gao, Seiichi Hirano, Sae Okazaki, Taichi Noda, Omar O. Abudayyeh, Jonathan S. Gootenberg, Hideto Mori, Seiya Oura, Benjamin Holmes, Mamoru Tanaka, Motoaki Seki, Hisato Hirano, Hiroyuki Aburatani, Ryuichiro Ishitani, Masahito Ikawa, Nozomu Yachie, Feng Zhang, Osamu NurekiThe RNAguided endonuclease Cas9 cleaves its target DNA and is a powerful genomeediting tool. However, the widely used Streptococcus pyogenes Cas9 enzyme (SpCas9) requires an NGG protospacer adjacent motif (PAM) for target recognition, thereby restricting the targetable genomic loci. Here, we report a rationally engineered SpCas9 variant (SpCas9NG) that can recognize relaxed NG PAMs. The crystal structure revealed that the loss of the basespecific interaction with the third G is compensated by newly introduced nonbasespecific interactions, enabling the NG PAM recognition. We showed that SpCas9NG induces indels at endogenous target sites bearing NG PAMs in human cells. Furthermore, we found that the fusion of SpCas9NG and the activationinduced cytidine deaminase (AID) mediates the CtoT conversion at target sites with NG PAMs in human cells.

Exciton States in MonolayerMoSe2andMoTe2Probed by Upconversion Spectroscopy Phys. Rev. X (IF 14.385) Pub Date : 20180918
B. Han, C. Robert, E. Courtade, M. Manca, S. Shree, T. Amand, P. Renucci, T. Taniguchi, K. Watanabe, X. Marie, L. E. Golub, M. M. Glazov, and B. Urbaszek 
Experimental Observation of Topologically Protected Helical Edge Modes in Patterned Elastic Plates Phys. Rev. X (IF 14.385) Pub Date : 20180918
M. Miniaci, R. K. Pal, B. Morvan, and M. Ruzzene 
Erratum: Binary Black Hole Mergers in the First Advanced LIGO Observing Run [Phys. Rev. X6, 041015 (2016)] Phys. Rev. X (IF 14.385) Pub Date : 20180918
B. P. Abbottet al.(LIGO Scientific and Virgo Collaborations) 
Certification and quantification of multilevel quantum coherence Phys. Rev. X (IF 14.385) Pub Date :
Martin Ringbauer, Thomas R. Bromley, Marco Cianciaruso, Ludovico Lami, W. Y. Sarah Lau, Gerardo Adesso, Andrew G. White, Alessandro Fedrizzi, and Marco PianiQuantum coherence, present whenever a quantum system exists in a superposition of , marks one of the fundamental departures from classical physics. Quantum coherence has recently been investigated rigorously within a resourcetheoretic formalism. However, the finergrained notion of , which explicitly takes into account the number of superposed classical states, has remained relatively unexplored. A comprehensive analysis of multilevel coherence, which acts as the singleparty analogue to multipartite entanglement, is essential for understanding natural quantum processes as well as for gauging the performance of quantum technologies. Here we develop the theoretical and experimental groundwork for characterizing and quantifying multilevel coherence. We further verify and lowerbound the robustness of multilevel coherence by performing a phase discrimination task, which is implemented experimentally with fourlevel quantum probes in a photonic setup. Our results contribute to understanding the operational relevance of genuine multilevel coherence, also by demonstrating the key role it plays in enhanced phase discrimination—a primitive for quantum communication and metrology—and suggest new ways to reliably and effectively test the quantum behaviour of physical systems.

Nonperturbative quantum electrodynamics in the Cherenkov effect Phys. Rev. X (IF 14.385) Pub Date :
Charles RoquesCarmes, Nicholas Rivera, John D. Joannopoulos, Marin Soljačić, and Ido KaminerQuantum Electrodynamics (QED) is one of the most precisely tested theories in the history of science, giving accurate predictions to a wide range of experimental observations. Recent experimental advances have allowed for the ability to probe physics on extremely short attosecond timescales, enabling ultrafast imaging of quantum dynamics. It is of great interest to extend our understanding of shorttime quantum dynamics to QED, where the focus is typically on longtime observables such as Smatrices, decay rates, and cross sections. That said, even for the simplest problems, solving the dynamics of the QED hamiltonian can lead to shorttime divergences, making it unclear how to arrive at physical predictions. We present an approach to regularize QED at short times, and apply it to the problem of describing the detailed time dynamics of free electron radiation into a medium, known as erenkov radiation. Surprisingly, we find a number of previously unknown phenomena yielding corrections to the conventional erenkov effect that could be observed in current experiments. Specifically, the rate of photon emission near the erenkov velocity threshold decreases relative to the conventional theory, effectively making the minimum velocity for erenkov radiation larger than the phase velocity of light in the medium. Finally, we reveal a bifurcation process creating radiation into new erenkov angles, occurring in the strongcoupling regime, which would be realizable by considering the radiation dynamics of highlycharged ions. Our results shed light on QED phenomena at short times and reveal surprising new physics in the erenkov effect.

Author Correction: Higherorder topology in bismuth Nat. Phys. (IF 22.727) Pub Date : 20180919
Frank Schindler, Zhijun Wang, Maia G. Vergniory, Ashley M. Cook, Anil Murani, Shamashis Sengupta, Alik Yu. Kasumov, Richard Deblock, Sangjun Jeon, Ilya Drozdov, Hélène Bouchiat, Sophie Guéron, Ali Yazdani, B. Andrei Bernevig, Titus NeupertAuthor Correction: Higherorder topology in bismuthAuthor Correction: Higherorder topology in bismuth, Published online: 19 September 2018; doi:10.1038/s4156701803084Author Correction: Higherorder topology in bismuth

An inconsistent friend Nat. Phys. (IF 22.727) Pub Date : 20180918
Matthew F. PuseyAn inconsistent friendAn inconsistent friend, Published online: 18 September 2018; doi:10.1038/s4156701802937Are there limits to the applicability of textbook quantum theory? Experiments haven’t found any yet, but a new theoretical analysis shows that treating your colleagues as quantum systems might be a step too far.

Erratum: Tests of General Relativity with GW150914 [Phys. Rev. Lett.116, 221101 (2016)] Phys. Rev. Lett. (IF 8.839) Pub Date : 20180918
B. P. Abbottet al.(LIGO Scientific and Virgo Collaboration) 
Erratum: GW170104: Observation of a 50SolarMass Binary Black Hole Coalescence at Redshift 0.2 [Phys. Rev. Lett.118, 221101 (2017)] Phys. Rev. Lett. (IF 8.839) Pub Date : 20180918
B. P. Abbottet al.(LIGO Scientific and Virgo Collaboration) 
Energy Storage via Topological Spin Textures Phys. Rev. Lett. (IF 8.839) Pub Date : 20180918
Yaroslav Tserkovnyak and Jiang Xiao 
Unconventional Multiband Superconductivity in BulkSrTiO3andLaAlO3/SrTiO3Interfaces Phys. Rev. Lett. (IF 8.839) Pub Date : 20180918
Thaís V. Trevisan, Michael Schütt, and Rafael M. Fernandes 
Spectral Evidence for Emergent Order inBa1−xNaxFe2As2 Phys. Rev. Lett. (IF 8.839) Pub Date : 20180918
M. Yi, A. Frano, D. H. Lu, Y. He, Meng Wang, B. A. Frandsen, A. F. Kemper, R. Yu, Q. Si, L. Wang, M. He, F. Hardy, P. Schweiss, P. Adelmann, T. Wolf, M. Hashimoto, S.K. Mo, Z. Hussain, M. Le Tacon, A. E. Böhmer, D.H. Lee, Z.X. Shen, C. Meingast, and R. J. Birgeneau 
Fragile Topology and Wannier Obstructions Phys. Rev. Lett. (IF 8.839) Pub Date : 20180918
Hoi Chun Po, Haruki Watanabe, and Ashvin Vishwanath 
Observation of Nonlocal Heat Flux Using Thomson Scattering Phys. Rev. Lett. (IF 8.839) Pub Date : 20180918
R. J. Henchen, M. Sherlock, W. Rozmus, J. Katz, D. Cao, J. P. Palastro, and D. H. Froula 
Painting Nonclassical States of Spin or Motion with Shaped Single Photons Phys. Rev. Lett. (IF 8.839) Pub Date : 20180918
Emily J. Davis, Zhaoyou Wang, Amir H. SafaviNaeini, and Monika H. SchleierSmith 
R'{e}nyi generalization of the accessible entanglement entropy Phys. Rev. Lett. (IF 8.839) Pub Date :
Hatem Barghathi, C. M. Herdman, and Adrian Del MaestroOperationally accessible entanglement in bipartite systems of indistinguishable particles could be reduced due to restrictions on the allowed local operations as a result of particle number conservation. In order to quantify this effect, Wiseman and Vaccaro [Phys. Rev. Lett. {91}, 097902 (2003)] introduced an operational measure of the von Neumann entanglement entropy. Motivated by advances in measuring entropies in quantum manybody systems subject to conservation laws, we derive a generalization of the operationally accessible entanglement that is both computationally and experimentally measurable. Using the Widom theorem, we investigate its scaling with the size of a spatial subregion for free fermions and find a logarithmically violated area law scaling, similar to the spatial entanglement entropy, with at most, a doublelog leadingorder correction. A modification of the correlation matrix method confirms our findings in systems of up to 105 particles.

Realization of a crosslinked chiral ladder with neutral fermions in a onedimensional optical lattice by orbitalmomentum coupling Phys. Rev. Lett. (IF 8.839) Pub Date :
Jin Hyoun Kang, Jeong Ho Han, and Y. ShinWe report the experimental realization of a crosslinked chiral ladder with ultracold fermionic atoms in a onedimensional optical lattice. In the ladder, the legs are formed by the orbital states of the optical lattice and the complex interleg links are generated by the orbitalchanging Raman transitions that are driven by a moving lattice potential superimposed onto the optical lattice. The effective magnetic flux per ladder plaquette is tuned by the spatial periodicity of the moving lattice, and the chiral currents are observed from the asymmetric momentum distributions of the orbitals. The effect of the complex cross links is demonstrated in quench dynamics by measuring the momentum dependence of the interorbital coupling strength. We discuss the topological phase transition of the chiral ladder system for the variations of the complex cross links.

Periodic Motion of Sedimenting Flexible Knots Phys. Rev. Lett. (IF 8.839) Pub Date : 20180918
Magdalena Gruziel, Krishnan Thyagarajan, Giovanni Dietler, Andrzej Stasiak, Maria L. EkielJeżewska, and Piotr Szymczak 
Dynamical control of order in a cavityBEC system Phys. Rev. Lett. (IF 8.839) Pub Date :
Jayson G. Cosme, Christoph Georges, Andreas Hemmerich, and Ludwig MatheyWe demonstrate dynamical control of the superradiant transition of cavityBEC system via periodic driving of the pump laser. We show that the dominant density wave order of the superradiant state can be suppressed, and that the subdominant competing order of BoseEinstein condensation emerges in the steady state. Furthermore, we show that additional, nonequilibrium density wave orders, which do not exist in equilibrium, can be stabilized dynamically. Finally, for strong driving, chaotic dynamics emerges.

Theory of the driftwave instability at arbitrary collisionality Phys. Rev. Lett. (IF 8.839) Pub Date :
R. Jorge, P. Ricci, and N. F. LoureiroA numerically efficient framework that takes into account the effect of the Coulomb collision operator at arbitrary collisionalities is introduced. Such model is based on the expansion of the distribution function on a HermiteLaguerre polynomial basis, to study the effects of collisions on magnetized plasma instabilities at arbitrary meanfree path. Focusing on the driftwave instability, we show that our framework allows retrieving established collisional and collisionless limits. At the intermediate collisionalities relevant for present and future magnetic nuclear fusion devices, deviations with respect to collision operators used in stateoftheart turbulence simulation codes show the need for retaining the full Coulomb operator in order to obtain both the correct instability growth rate and eigenmode spectrum, which, for example, may significantly impact quantitative predictions of transport. The exponential convergence of the spectral representation that we propose makes the representation of the velocity space dependence, including the full collision operator, more efficient than standard finite difference methods.

Dynamo effect and turbulence in hydrodynamic Weyl metals Phys. Rev. Lett. (IF 8.839) Pub Date :
Victor Galitski, Mehdi Kargarian, and Sergey SyzranovThe dynamo effect is a class of macroscopic phenomena responsible for generation and maintaining magnetic fields in astrophysical bodies. It hinges on hydrodynamic threedimensional motion of conducting gases and plasmas that achieve high hydrodynamic and/or magnetic Reynolds numbers due to large length scales involved. The existing laboratory experiments modeling dynamos are challenging and involve large apparatuses containing conducting fluids subject to fast helical flows. Here we propose that electronic solidstate materials  in particular, hydrodynamic metals  may serve as an alternative platform to observe some aspects of the dynamo effect. Motivated by recent experimental developments, this paper focuses on hydrodynamic Weyl semimetals, where the dominant scattering mechanism is due to interactions. We derive NavierStokes equations along with equations of magnetohydrodynamics that describe transport of Weyl electronhole plasma appropriate in this regime. We estimate the hydrodynamic and magnetic Reynolds numbers for this system. The latter is a key figure of merit of the dynamo mechanism. We show that it can be relatively large to enable observation of the dynamoinduced magnetic field bootstrap in experiment. Finally, we generalize the simplest dynamo instability model  Ponomarenko dynamo  to the case of a hydrodynamic Weyl semimetal and show that the chiral anomaly term reduces the threshold magnetic Reynolds number for the dynamo instability.

Mass difference for charged quarks from asymptotically safe quantum gravity Phys. Rev. Lett. (IF 8.839) Pub Date :
Astrid Eichhorn and Aaron HeldWe propose a scenario to retrodict the top and bottom mass and the Abelian gauge coupling from first principles in a microscopic model including quantum gravity. In our approximation, antiscreening quantumgravity fluctuations induce an asymptotically safe fixed point for the Abelian hypercharge leading to a uniquely fixed infrared value that is observationally viable for a particular choice of microscopic gravitational parameters. The unequal quantum numbers of the top and bottom quark lead to different fixedpoint values for the top and bottom Yukawa under the impact of gauge and gravity fluctuations. This results in a dynamically generated mass difference between the two quarks. To work quantitatively, the preferred ratio of electric charges of bottom and top in our approximation lies in close vicinity to the StandardModel value of $Q_b/Q_t =1/2$.

From birefringent electrons to marginal or nonFermi liquid of relativistic spin1/2 fermions: An emergent superuniversality Phys. Rev. Lett. (IF 8.839) Pub Date :
Bitan Roy, Malcolm P. Kennett, Kun Yang, and Vladimir JuričIćWe present the quantum critical theory of an interacting nodal Fermiliquid of quasirelativisitc pseudospin3/2 fermions that have a noninteracting \emph{birefringent} spectrum with \emph{two} distinct Fermi velocities. When such quasiparticles interact with gapless bosonic degrees of freedom that mediate either the longrange Coulomb interaction or its short range component (responsible for spontaneous symmetry breaking), in the deep infrared or quantum critical regime in two dimensions the system is respectively described by a \emph{marginal} or a \emph{nonFermi liquid} of relativistic spin1/2 fermions (possessing a \emph{unique} velocity), and is always a \emph{marginal Fermi liquid} in three dimensions. We consider a possible generalization of these scenarios to fermions with an arbitrary halfoddinteger spin, and conjecture that critical spin1/2 excitations represent a \emph{superuniversal} description of the entire family of interacting quasirelativistic fermions.

Beliaev damping of spinorbit coupled BoseEinstein condensate Phys. Rev. Lett. (IF 8.839) Pub Date :
Rukuan Wu and Zhaoxin LiangBeliaev damping provides a fundamental mechanism for dissipation of quasiparticles. Previous research has shown that the twocomponent internal degrees of freedom has no nontrivial effect on Beliaev damping. Here we provide the first example where the spinor nature of Bose gases can manifest itself in the Beliaev damping by way of spinobit coupling. We identify novel features of Beliaev decay rate due to spinorbit coupling, in particular, it shows explicit dependence on the spindensity interaction and diverges at the interactionmodified phase boundary between the zeromomentum and planewave phases. This represents a manifestation of the effect of spinorbit coupling in the beyondmeanfield regime, which by breaking Galilean invariance couples excitations in the density and spinchannels. We further show that the measurement of Beliaev damping rate is experimentally feasible through the measurement of spin polarizability susceptibility which has been already achieved in spinorbitcoupled Bose gases.

Secure quantum key distribution over 421 km of optical fiber Phys. Rev. Lett. (IF 8.839) Pub Date :
Alberto Boaron, Gianluca Boso, Davide Rusca, Cédric Vulliez, Claire Autebert, Misael Caloz, Matthieu Perrenoud, Gaëtan Gras, Félix Bussières, MingJun Li, Daniel Nolan, Anthony Martin, and Hugo ZbindenWe present a quantum key distribution system with a 2.5~GHz repetition rate using a threestate timebin protocol combined with a onedecoy approach. Taking advantage of superconducting singlephoton detectors optimized for quantum key distribution and ultra lowloss fiber, we can distribute secret keys at a maximum distance of 421~km and obtain secret key rates of 6.5~bps over 405~km.

Diffusion Dynamics and Optimal Coupling in Multiplex Networks with Directed Layers Phys. Rev. X (IF 14.385) Pub Date : 20180917
Alejandro Tejedor, Anthony Longjas, Efi FoufoulaGeorgiou, Tryphon T. Georgiou, and Yamir Moreno 
Strength of Correlations in Strongly Recurrent Neuronal Networks Phys. Rev. X (IF 14.385) Pub Date : 20180917
Ran Darshan, Carl van Vreeswijk, and David Hansel 
Deterministic and generalized framework for unsupervised learning with restricted Boltzmann machines Phys. Rev. X (IF 14.385) Pub Date :
Eric W. Tramel, Marylou Gabrié, Andre Manoel, Francesco Caltagirone, and Florent KrzakalaRestricted Boltzmann machines (RBMs) are energybased neuralnetworks which are commonly used as the building blocks for deep architectures neural architectures. In this work, we derive a deterministic framework for the training, evaluation, and use of RBMs based upon the ThoulessAndersonPalmer (TAP) meanfield approximation of widelyconnected systems with weak interactions coming from spinglass theory. While the TAP approach has been extensively studied for fullyvisible binary spin systems, our construction is generalized to latentvariable models, as well as to arbitrarily distributed realvalued spin systems with bounded support. In our numerical experiments, we demonstrate the effective deterministic training of our proposed models and are able to show interesting features of unsupervised learning which could not be directly observed with sampling. Additionally, we demonstrate how to utilize our TAPbased framework for leveraging trained RBMs as joint priors in denoising problems.

Competing inversionbased lasing and Raman lasing in doped silicon Phys. Rev. X (IF 14.385) Pub Date :
S. G. Pavlov, N. Deßmann, B. Redlich, A. F. G. van der Meer, N. V. Abrosimov, H. Riemann, R. Kh. Zhukavin, V. N. Shastin, and H. W. HübersWe report on an optically pumped laser where photons are simultaneously generated by population inversion and by stimulated Raman scattering in the same active medium, namely crystalline silicon doped by bismuth (Si:Bi). The medium utilizes three electronic levels: ground state (\textbar 1$\rangle $: 1s(A$_{1})$ in Si:Bi), upper (\textbar 3$\rangle $: 2p$_{\pm })$ and lower (\textbar 2$\rangle $: 1s(E)) laser levels. The \textbar 1$\rangle \leftrightarrow $\textbar 3$\rangle $ and \textbar 2$\rangle \leftrightarrow $\textbar 3$\rangle $ transitions are optically allowed and the \textbar 1$\rangle \leftrightarrow $\textbar 2$\rangle $ transition is Raman active. Lasing based on population inversion occurs between the states \textbar 3$\rangle $ and \textbar 2$\rangle $ while Raman scattering benefits from the Ramanactive transition. At high pump power the inversionbased stimulated emission \textbar 3$\rangle \to $\textbar 2$\rangle $ disappears, because electronic scattering from \textbar 1$\rangle $~to~\textbar 2$\rangle $ via a virtual state dominates and the electrons are excited into \textbar 2$\rangle $ rather than into \textbar 3$\rangle $. Starting as population inversion based lasing, it ends as stimulated Raman scattering. Our model shows that such a competition occurs on the time scale of the 10~ps long pump pulse.

Entanglement entropy: Holography and renormalization group Rev. Mod. Phys. (IF 36.367) Pub Date : 20180917
Tatsuma Nishioka 
Membraneinduced hydroelastic migration of a particle surfing its own wave Nat. Phys. (IF 22.727) Pub Date : 20180917
Bhargav Rallabandi, Naomi Oppenheimer, Matan Yah Ben Zion, Howard A. StoneWhile coupling between fluid flow and soft elastic surfaces is common in biology and engineering, an analytical description is challenging as it often involves nonlinear dynamics. Here we show using theory and experiments that a small particle moving along an elastic membrane through a viscous fluid is repelled from the membrane due to hydroelastic forces. The flow field produces an elastic disturbance in the membrane leading to particle–wave coupling. We derive an analytic expression for the particle trajectory and find that the normal migration velocity of the particle is quadratic in its speed and depends on a combination of the tension and bending resistance of the membrane. Experimentally, we measure the normal displacement of spheres sedimenting under gravity along a suspended elastic membrane and find quantitative agreement with the theoretical predictions with no fitting parameters. We experimentally demonstrate that the effect is strong enough for separation and sorting of particles on the basis of both their size and density. We discuss the significance of our results for particles interacting with biological membranes, and propose the use of our model for membrane elasticity measurements.

Visualization of the periodic modulation of Cooper pairing in a cuprate superconductor Nat. Phys. (IF 22.727) Pub Date : 20180917
Wei Ruan, Xintong Li, Cheng Hu, Zhenqi Hao, Haiwei Li, Peng Cai, Xingjiang Zhou, DungHai Lee, Yayu WangIn cuprate superconductors, the existence of various intertwined orders associated with spin, charge and Cooper pairs1,2 is an obstacle in understanding the mechanism of Cooper pairing. The ubiquitous charge order is particularly important2,3,4,5,6,7. Various theories have been proposed to explain the origin of the charge order and its implications for the superconducting phase, including charge stripes8, electronic nematicity8,9 and Fermi surface instability5,10. A highly appealing physical picture is the ‘pair density wave’, a spatially periodic modulation of Cooper pairing, which may also induce a charge order2,11,12,13,14,15,16,17,18,19,20,21. To elucidate the existence and nature of the pair density wave, we use scanning tunnelling microscopy to investigate a severely underdoped cuprate, in which superconductivity just emerges on top of a pronounced chequerboard charge order. We observe a periodic modulation of both the superconducting coherence peak and gap depth, indicating the existence of a density wave order of Cooper pairing based on the empirical relationship between superconducting coherence and superfluid density22,23,24,25,26,27. The pair density wave has the same spatial periodicity as the charge order, and the amplitudes of the two orders exhibit clear positive correlation. These results shed new light on the origin of and interplay between the charge order and Cooper pairing modulation in the cuprates.

Collective mechanical adaptation of honeybee swarms Nat. Phys. (IF 22.727) Pub Date : 20180917
O. Peleg, J. M. Peters, M. K. Salcedo, L. MahadevanHoneybee Apis mellifera swarms form large congested treehanging clusters made solely of bees attached to each other1. How these structures are maintained under the influence of dynamic mechanical forcing is unknown. To address this, we created pendant clusters and subject them to dynamic loads of varying orientation, amplitude, frequency and duration. We find that horizontally shaken clusters adapt by spreading out to form wider, flatter cones that recover their original shape when unloaded. Measuring the response of a cluster to an impulsive pendular excitation shows that flattened cones deform less and relax faster than the elongated ones (that is, they are more stable). Particlebased simulations of a passive assemblage suggest a behavioural hypothesis: individual bees respond to local variations in strain by moving up the strain gradient, which is qualitatively consistent with our observations of individual bee movement during dynamic loading. The simulations also suggest that vertical shaking will not lead to significant differential strains and thus no shape adaptation, which we confirmed experimentally. Together, our findings highlight how a superorganismal structure responds to dynamic loading by actively changing its morphology to improve the collective stability of the cluster at the expense of increasing the average mechanical burden of an individual.

Nonreciprocal interband Brillouin modulation Nat. Photon. (IF 32.521) Pub Date : 20180917
Eric A. Kittlaus, Nils T. Otterstrom, Prashanta Kharel, Shai Gertler, Peter T. RakichNonreciprocal light propagation is essential to control optical crosstalk and backscatter in photonic systems. However, realizing highfidelity nonreciprocity in lowloss integrated photonic circuits remains challenging. Here, we experimentally demonstrate a form of nonlocal acoustooptic light scattering to produce nonreciprocal singlesideband modulation and mode conversion in an integrated silicon photonic platform. In this system, a travellingwave acoustic phonon driven by optical forces in a silicon waveguide spatiotemporally modulates light in a separate waveguide through linear interband Brillouin scattering. This process extends narrowband optomechanicsbased schemes for nonreciprocity to travellingwave physics, enabling large operation bandwidths of more than 125 GHz and up to 38 dB of nonreciprocal contrast between forward and backwardpropagating optical waves. The modulator operation wavelength is tunable over a 35nm range by varying the optical drive wavelength. Such travellingwave acoustooptic interactions provide a promising path toward the realization of broadband, lowloss isolators and circulators within integrated photonics.

Thermal Critical Points and Quantum Critical End Point in the Frustrated Bilayer Heisenberg Antiferromagnet Phys. Rev. Lett. (IF 8.839) Pub Date : 20180917
J. Stapmanns, P. Corboz, F. Mila, A. Honecker, B. Normand, and S. Wessel 
Binary TwoDimensional Honeycomb Lattice with Strong SpinOrbit Coupling and ElectronHole Asymmetry Phys. Rev. Lett. (IF 8.839) Pub Date : 20180917
Jian Gou, Bingyu Xia, Hang Li, Xuguang Wang, Longjuan Kong, Peng Cheng, Hui Li, Weifeng Zhang, Tian Qian, Hong Ding, Yong Xu, Wenhui Duan, Kehui Wu, and Lan Chen 
Fractional Excitonic Insulator Phys. Rev. Lett. (IF 8.839) Pub Date : 20180917
Yichen Hu, Jörn W. F. Venderbos, and C. L. Kane 
Quantum Spin Hall Effect and Spin Bott Index in a Quasicrystal Lattice Phys. Rev. Lett. (IF 8.839) Pub Date : 20180917
Huaqing Huang and Feng Liu 
Observation of Higgs Boson Decay to Bottom Quarks Phys. Rev. Lett. (IF 8.839) Pub Date : 20180917
A. M. Sirunyanet al.(CMS Collaboration) 
Quantum Anomaly and 2D3D Crossover in Strongly Interacting Fermi Gases Phys. Rev. Lett. (IF 8.839) Pub Date : 20180917
T. Peppler, P. Dyke, M. Zamorano, I. Herrera, S. Hoinka, and C. J. Vale 
Anomalous Breaking of Scale Invariance in a TwoDimensional Fermi Gas Phys. Rev. Lett. (IF 8.839) Pub Date : 20180917
M. Holten, L. Bayha, A. C. Klein, P. A. Murthy, P. M. Preiss, and S. Jochim 
Stochastic polarization instability in PbTiO$_3$ Phys. Rev. Lett. (IF 8.839) Pub Date :
K. Datta, I. Margaritescu, D. A. Keen, and B. MihailovaAlthough discussions of structural phase transitions in prototypical ferroelectric systems with the perovskite structure, such as BaTiO$_3$ and PbTiO$_3$, started almost seventy years ago, an atomiclevel description of the polar characteristics as a function of temperature, pressure and composition remains topical. Here we provide a novel quantitative description of the temperaturedriven local structural correlations in PbTiO$_3$ via the development of characteristic relative cationic shifts. The results give new insights into the phase transition beyond those reliant on the longrange order. The ferroelectrictoparaelectric transition of PbTiO$_3$ is realized by the extent of a stochastic polarization instability driven by a progressive misalignment instead of a complete disappearance of the local dipoles, which further suggests that such polarization instability is chemically induced at the morphotropic phase boundary of PbTiO$_3$based solid solutions with giant piezoelectric effect. As such, our results not only identify the evolving atomistic disorder in a perovskitebased ferroelectric system, but also suggest that polarizationinstability can serve as a generic fingerprint for phase transitions as well as for better understanding structureproperty relationships in PbTiO$_3$based ferroelectric solid solutions.

Highdimensional quantum communication complexity beyond strategies based on Bell's theorem Phys. Rev. Lett. (IF 8.839) Pub Date :
Daniel Martínez, Armin Tavakoli, Mauricio Casanova, Gustavo Cañas, Breno Marques, and Gustavo LimaQuantum resources can improve communication complexity problems (CCPs) beyond their classical constraints. One quantum approach is to share entanglement and create correlations violating a Bell inequality, which can then assist classical communication. A second approach is to resort solely to the preparation, transmission and measurement of a single quantum system; in other words quantum communication. Here, we show the advantages of the latter over the former in highdimensional Hilbert space. We focus on a family of CCPs, based on facet Bell inequalities, study the advantage of highdimensional quantum communication, and realise such quantum communication strategies using up to tendimensional systems. The experiment demonstrates, for growing dimension, an increasing advantage over quantum strategies based on Bell inequality violation. For sufficiently high dimensions, quantum communication also surpasses the limitations of the postquantum Bell correlations obeying only locality in the macroscopic limit. We find that the advantages are tied to the use of measurements that are not rankone projective, and provide an experimental semideviceindependent falsification of such measurements in Hilbert space dimension six.

Initiating and monitoring the evolution of single electrons within atomdefined structures Phys. Rev. Lett. (IF 8.839) Pub Date :
Mohammad Rashidi, Wyatt Vine, Thomas Dienel, Lucian Livadaru, Jacob Retallick, Taleana Huff, Konrad Walus, and Robert A. WolkowUsing a noncontact atomic force microscope we track and manipulate the position of single electrons confined to atomic structures engineered from silicon dangling bonds on the hydrogen terminated silicon surface. An attractive tip surface interaction mechanically manipulates the equilibrium position of a surface silicon atom, causing rehybridization that stabilizes a negative charge at the dangling bond. This is applied to controllably switch the charge state of individual dangling bonds. Because this mechanism is based on short range interactions and can be performed without applied bias voltage, we maintain both sitespecific selectivity and singleelectron control. We extract the short range forces involved with this mechanism by subtracting the long range forces acquired on a dimer vacancy site. As a result of relaxation of the silicon lattice to accommodate negatively charged dangling bonds, we observe charge configurations of dangling bond structures that remain stable for many seconds at 4.5~K. Subsequently, we use charge manipulation to directly prepare the ground state and metastable charge configurations of dangling bond structures composed of up to six atoms.

Breakdown of nonrelativistic QCD factorization in processes involving two quarkonia and its cure Phys. Rev. Lett. (IF 8.839) Pub Date :
ZhiGuo He, Bernd A. Kniehl, and XiangPeng WangWe study inclusive processes involving two heavy quarkonia in nonrelativisitic QCD (NRQCD) and demonstrate that, in the presence of two Pwave Fock states, NRQCD factorization breaks down, leaving uncanceled infrared singularities. As phenomenologically important examples, we consider the decay $\Upsilon \to \chi_{cJ}+X$ via $b\bar{b}(^3P_{J_b}^{[8]})\to c\bar{c}(^3P_J^{[1]})+gg$ and the production process $e^+e^\to J/\psi+\chi_{cJ}+X$ via $e^{+}e^{}\to c\bar{c}(^3P_{J_1}^{[8]})+c\bar{c}(^3P_J^{[1]})+g$. We infer that such singularities will appear for double quarkonium hadroproduction at nexttoleading order. As a solution to this problem, we introduce to NRQCD effective field theory new types of operators whose quantum corrections absorb these singularities.

Quantization of the thermal Hall conductivity at small Hall angles Phys. Rev. Lett. (IF 8.839) Pub Date :
Mengxing Ye, Gábor B. Halász, Lucile Savary, and Leon BalentsWe consider the effect of coupling between phonons and a chiral Majorana edge in a gapped chiral spin liquid with Ising anyons (e.g., Kitaev's nonabelian spin liquid on the honeycomb lattice). This is especially important in the regime in which the longitudinal bulk heat conductivity $\kappa_{xx}$ due to phonons is much larger than the expected quantized thermal Hall conductance $\kappa_{xy}^{\rm q}=\frac{\pi T}{12} \frac{k_B^2}{\hbar}$ of the ideal isolated edge mode, so that the thermal Hall angle, i.e., the angle between the thermal current and the temperature gradient, is small. By modeling the interaction between a Majorana edge and bulk phonons, we show that the exchange of energy between the two subsystems leads to a transverse component of the bulk current and thereby an {\em effective} Hall conductivity. Remarkably, the latter is equal to the quantized value when the edge and bulk can thermalize, which occurs for a Hall bar of length $L \gg \ell$, where $\ell$ is a thermalization length. We obtain $\ell \sim T^{5}$ for a model of the Majoranaphonon coupling. We also find that the quality of the quantization depends on the means of measuring the temperature and, surprisingly, a more robust quantization is obtained when the lattice, not the spin, temperature is measured. We present general hydrodynamic equations for the system, detailed results for the temperature and current profiles, and an estimate for the coupling strength and its temperature dependence based on a microscopic model Hamiltonian. Our results may explain recent experiments observing a quantized thermal Hall conductivity in the regime of small Hall angle, $\kappa_{xy}/\kappa_{xx} \sim 10^{3}$, in $\alpha$RuCl$_3$.

Confinement of positrons exceeding one second in a supported magnetic dipole trap Phys. Rev. Lett. (IF 8.839) Pub Date :
J. HornStanja, S. Niß l, U. Hergenhahn, T. Sunn Pedersen, H. Saitoh, E. V. Stenson, M. Dickmann, C. Hugenschmidt, M. Singer, M. R. Stoneking, and J. R. DanielsonAn ensemble of lowenergy positrons injected into a supported magnetic dipole trap can remain trapped for more than a second. Trapping experiments with and without a positive magnet bias yield confinement times up to $\tau_A=(1.5\pm0.1)\,$s and $\tau_B=(0.28\pm0.04)\,$s, respectively. Supported by singleparticle simulations, we conclude that the dominant mechanism limiting the confinement in this trap is scattering off of neutrals, which can lead to both radial transport and parallel losses onto the magnet surface. These results provide encouragement for plans to confine an electronpositron plasma in a levitated dipole trap.

Short note on the density of states in 3D Weyl semimetals Phys. Rev. Lett. (IF 8.839) Pub Date :
K. Ziegler and A. SinnerThe average density of states in a disordered threedimensional Weyl system is discussed in the case of a continuous distribution of random scattering. Our results clearly indicate that the average density of states does not vanish, reflecting the absence of a critical point for a metalinsulator transition. This calculation supports recent suggestions of an avoided quantum critical point in the disordered threedimensional Weyl semimetal. However, the effective density of states can be very small such that the saddleapproximation with a vanishing density of states might be valid for practical cases.

Generation of a cat state in an optical sideband Phys. Rev. Lett. (IF 8.839) Pub Date :
Takahiro Serikawa, Junichi Yoshikawa, Shuntaro Takeda, Hidehiro Yonezawa, Timothy C. Ralph, Elanor H. Huntington, and Akira FurusawaWe propose a method to subtract a photon from a double sideband mode of continuouswave light. The central idea is to use phase modulation as a frequency sideband beamsplitter in the heralding photon subtraction scheme, where a small portion of the sideband mode is downconverted to 0\,Hz to provide a trigger photon. An optical cat state is created by applying the proposed method to a squeezed state at 500MHz sideband, which is generated by an optical parametric oscillator. The Wigner function of the cat state reconstructed from a direct homodyne measurement of the 500\,MHz sideband modes shows the negativity of $W(0,0) = 0.088\pm0.001$ without any loss corrections.

Timeasymmetric loop around an exceptional point over the full optical communications band Nature (IF 41.577) Pub Date : 20180917
Jae Woong Yoon, Youngsun Choi, Choloong Hahn, Gunpyo Kim, Seok Ho Song, KiYeon Yang, Jeong Yub Lee, Yongsung Kim, Chang Seung Lee, Jai Kwang Shin, HongSeok Lee, Pierre Berini 
Sensation, movement and learning in the absence of barrel cortex Nature (IF 41.577) Pub Date : 20180917
Y. Kate Hong, Clay O. Lacefield, Chris C. Rodgers, Randy M. Bruno 
Structure of the membraneassembled retromer coat determined by cryoelectron tomography Nature (IF 41.577) Pub Date : 20180917
Oleksiy Kovtun, Natalya Leneva, Yury S. Bykov, Nicholas Ariotti, Rohan D. Teasdale, Miroslava Schaffer, Benjamin D. Engel, David. J. Owen, John A. G. Briggs, Brett M. Collins 
The role of miniaturization in the evolution of the mammalian jaw and middle ear Nature (IF 41.577) Pub Date : 20180917
Stephan Lautenschlager, Pamela G. Gill, ZheXi Luo, Michael J. Fagan, Emily J. Rayfield 
Spectrally resolved specular reflections of thermal phonons from atomically rough surfaces Phys. Rev. X (IF 14.385) Pub Date :
Navaneetha K. Ravichandran, Hang Zhang, and Austin J. MinnichThe reflection of waves from rough surfaces is a fundamental process that plays a role in diverse fields such as optics, acoustics, and seismology. While a quantitative understanding of the process has long been established for many types of waves, the precise manner in which thermal phonons of specific wavelengths reflect from atomically rough surfaces remains unclear owing to limited control over THz frequency phonon generation and detection. Knowledge of these processes is critical for many applications, however, and is particularly important for recent attempts to create novel materials by coherently interfering thermal phonons. Here, we report measurements of a key property for these efforts, the phonon wavelengthdependent specularity parameter, which describes the probability of specular reflection of thermal phonons at a surface. Our observations demonstrate that THz thermal phonons specularly reflect from surfaces with Angstromscale roughness, and further show that completely diffuse reflections occur with surface imperfections on the scale of only a few atomic planes. Our work provides key insights into the surface perfection required for coherent manipulation of heat and demonstrates a general approach to probe thermal phonon interactions with surfaces with considerable microscopic detail.

The conformal bootstrap: Theory, numerical techniques, and applications Rev. Mod. Phys. (IF 36.367) Pub Date :
David Poland, Slava Rychkov, and Alessandro VichiConformal field theories have been long known to describe the fascinating universal physics of scale invariant critical points. They describe continuous phase transitions in fluids, magnets, and numerous other materials, while at the same time sit at the heart of our modern understanding of quantum field theory. For decades it has been a dream to study these intricate strongly coupled theories nonperturbatively using symmetries and other consistency conditions. This idea, called the conformal bootstrap, saw some successes in two dimensions but it is only in the last ten years that it has been fully realized in three, four, and other dimensions of interest. This renaissance has been possible both due to significant analytical progress in understanding how to set up the bootstrap equations and the development of numerical techniques for finding or constraining their solutions. These developments have led to a number of groundbreaking results, including world record determinations of critical exponents and correlation function coecients in the Ising and O(N) models in three dimensions. This article will review these exciting developments for newcomers to the bootstrap, giving an introduction to conformal field theories and the theory of conformal blocks, describing numerical techniques for the bootstrap based on convex optimization, and summarizing in detail their applications to fixed points in three and four dimensions with no or minimal supersymmetry.

Transition from Asynchronous to Oscillatory Dynamics in Balanced Spiking Networks with Instantaneous Synapses Phys. Rev. Lett. (IF 8.839) Pub Date : 20180917
Matteo di Volo and Alessandro Torcini 
ConstraintBased Approach to Granular Dispersion Rheology Phys. Rev. Lett. (IF 8.839) Pub Date : 20180917
B. M. Guy, J. A. Richards, D. J. M. Hodgson, E. Blanco, and W. C. K. Poon 
Anomalous Hall Effect in 2D Dirac Materials Phys. Rev. Lett. (IF 8.839) Pub Date : 20180917
Manuel Offidani and Aires Ferreira 
Avalanche Behavior in Creep Failure of Disordered Materials Phys. Rev. Lett. (IF 8.839) Pub Date : 20180917
D. F. Castellanos and M. Zaiser
Some contents have been Reproduced by permission of The Royal Society of Chemistry.