Read by QxMD icon Read

Physical Review Letters

Igor Marinković, Andreas Wallucks, Ralf Riedinger, Sungkun Hong, Markus Aspelmeyer, Simon Gröblacher
Over the past few decades, experimental tests of Bell-type inequalities have been at the forefront of understanding quantum mechanics and its implications. These strong bounds on specific measurements on a physical system originate from some of the most fundamental concepts of classical physics-in particular that properties of an object are well-defined independent of measurements (realism) and only affected by local interactions (locality). The violation of these bounds unambiguously shows that the measured system does not behave classically, void of any assumption on the validity of quantum theory...
November 30, 2018: Physical Review Letters
Song-Bo Zhang, Johanna Erdmenger, Björn Trauzettel
We study Josephson junctions based on inversion-asymmetric but time-reversal symmetric Weyl semimetals under the influence of Zeeman fields. We find that, due to distinct spin textures, the Weyl nodes of opposite chirality respond differently to an external magnetic field. Remarkably, a Zeeman field perpendicular to the junction direction results in a phase shift of opposite sign in the current-phase relations of opposite chirality. This leads to a finite chirality Josephson current (CJC) even in the absence of a phase difference across the junction...
November 30, 2018: Physical Review Letters
Rong Yu, Jian-Xin Zhu, Qimiao Si
Motivated by the recent low-temperature experiments on bulk FeSe, we study the electron correlation effects in a multiorbital model for this compound in the nematic phase using the U(1) slave-spin theory. We find that a finite nematic order helps to stabilize an orbital selective Mott phase. Moreover, we propose that when the d- and s-wave bond nematic orders are combined with the ferro-orbital order, there exists a surprisingly large orbital selectivity between the xz and yz orbitals even though the associated band splitting is relatively small...
November 30, 2018: Physical Review Letters
Shadi Fatayer, Nikolaj Moll, Sara Collazos, Dolores Pérez, Enrique Guitián, Diego Peña, Leo Gross, Gerhard Meyer
By atom manipulation we performed on-surface chemical reactions of a single molecule on a multilayer insulating film using noncontact atomic force microscopy. The single-electron sensitivity of atomic force microscopy allows us to follow the addition of single electrons to the molecule and the investigation of the reaction products. By performing a novel strategy based on long-lived doubly charged states a single molecule is fragmented. The fragmentation can be reverted by again changing the charge state of the system, characterizing a reversible reaction...
November 30, 2018: Physical Review Letters
Bibek Pokharel, Namit Anand, Benjamin Fortman, Daniel A Lidar
Quantum computers must be able to function in the presence of decoherence. The simplest strategy for decoherence reduction is dynamical decoupling (DD), which requires no encoding overhead and works by converting quantum gates into decoupling pulses. Here, using the IBM and Rigetti platforms, we demonstrate that the DD method is suitable for implementation in today's relatively noisy and small-scale cloud-based quantum computers. Using DD, we achieve substantial fidelity gains relative to unprotected, free evolution of individual superconducting transmon qubits...
November 30, 2018: Physical Review Letters
Hiroyuki Endo, Chisa Hotta, Akira Shimizu
We propose a self-validating scheme to calculate the unbiased responses of quantum many-body systems to external fields of arbitrary strength at any temperature. By switching on a specified field to a thermal pure quantum state of an isolated system, and tracking its time evolution, one can observe an intrinsic thermalization process driven solely by many-body effects. The transient behavior before thermalization contains rich information on excited states, giving the linear and nonlinear response functions at all frequencies...
November 30, 2018: Physical Review Letters
Steven Weinberg
The standard model is a quantum field theory that successfully accounts for the strong, weak, and electromagnetic interactions of the known elementary particles. In this essay I reminisce about the forerunners of the standard model, the beginnings of the model half a century ago, and its development and confirmation from then to the present.
November 30, 2018: Physical Review Letters
M W Coughlin, J Harms, J Driggers, D J McManus, N Mukund, M P Ross, B J J Slagmolen, K Venkateswara
Newtonian gravitational noise from seismic fields will become a limiting noise source at low frequency for second-generation, gravitational-wave detectors. It is planned to use seismic sensors surrounding the detectors' test masses to coherently subtract Newtonian noise using Wiener filters derived from the correlations between the sensors and detector data. In this Letter, we use data from a seismometer array deployed at the corner station of the Laser Interferometer Gravitational Wave Observatory (LIGO) Hanford detector combined with a tiltmeter for a detailed characterization of the seismic field and to predict achievable Newtonian-noise subtraction levels...
November 30, 2018: Physical Review Letters
M Dinkgreve, M A J Michels, T G Mason, D Bonn
The non-Newtonian flow behavior of thermal and athermal disordered systems of dispersed uniform particles at high densities have strikingly similar features. By investigating the flow curves of yield-stress fluids and colloidal glasses having different volume fractions, particle sizes, and interactions, we show that both thermal and athermal systems exhibit power-law scaling with respect to the glass and jamming point, respectively, with the same exponents. All yield-stress flow curves can be scaled onto a single universal curve using the Laplace pressure as the stress scale for athermal systems and the osmotic pressure for the thermal systems...
November 30, 2018: Physical Review Letters
Cristian D Batista, Mikhail Shifman, Zhentao Wang, Shang-Shun Zhang
We discuss noncollinear magnetic phenomena whose local order parameter is characterized by more than one spin vector. By focusing on the simple cases of 2D triangular and 3D pyrochlore lattices, we demonstrate that their low-energy theories can be described by a one-parametric class of sigma models continuously interpolating between the classical Heisenberg model and the principal chiral model Tr(∂_{a}U∂_{a}U^{†}) for all U∈SU(2). The target space can be viewed as a U(1) fibration over the CP(1) space...
November 30, 2018: Physical Review Letters
Shuyi Liu, Martin Wolf, Takashi Kumagai
We report plasmon-assisted resonant electron tunneling from a Ag or Au tip to field emission resonances (FERs) of a Ag(111) surface induced by cw laser excitation of a scanning tunneling microscope (STM) junction at visible wavelengths. As a hallmark of the plasmon-assisted resonant tunneling, we observe a downshift of the first peak in the FER spectra by a fixed amount equal to the incident photon energy. STM-induced luminescence measurement for the Ag and Au tip reveals the clear correlation between the laser-induced change in the FER spectra and the plasmonic properties of the junction...
November 30, 2018: Physical Review Letters
A H Reiman, N J Fisch
Currents driven by radio frequency (rf) waves in the interior of magnetic islands can stabilize deleterious tearing modes in tokamaks. Present analyses of stabilization assume that the local electron acceleration is unaffected by the presence of the island. However, the power deposition and electron acceleration are sensitive to the perturbation of the temperature. The nonlinear feedback on the power deposition in the island increases the temperature perturbation, and can lead to a bifurcation of the solution to the steady-state heat diffusion equation...
November 30, 2018: Physical Review Letters
Dongfang Li, Sinan Karaveli, Sébastien Cueff, Wenhao Li, Rashid Zia
We experimentally demonstrate that the radiative decay rate of a quantum emitter is determined by the combined electric and magnetic local density of optical states (LDOS). A Drexhage-style experiment was performed for two distinct quantum emitters, divalent nickel ions in magnesium oxide and trivalent erbium ions in yttrium oxide, which both support nearly equal mixtures of isotropic electric dipole and magnetic dipole transitions. The disappearance of lifetime oscillations as a function of emitter-interface separation distance confirms that the electromagnetic LDOS refers to the total mode density, and thus similar to thermal emission, these unique electronic emitters effectively excite all polarizations and orientations of the electromagnetic field...
November 30, 2018: Physical Review Letters
P A R Ade, Z Ahmed, R W Aikin, K D Alexander, D Barkats, S J Benton, C A Bischoff, J J Bock, R Bowens-Rubin, J A Brevik, I Buder, E Bullock, V Buza, J Connors, J Cornelison, B P Crill, M Crumrine, M Dierickx, L Duband, C Dvorkin, J P Filippini, S Fliescher, J Grayson, G Hall, M Halpern, S Harrison, S R Hildebrandt, G C Hilton, H Hui, K D Irwin, J Kang, K S Karkare, E Karpel, J P Kaufman, B G Keating, S Kefeli, S A Kernasovskiy, J M Kovac, C L Kuo, N A Larsen, K Lau, E M Leitch, M Lueker, K G Megerian, L Moncelsi, T Namikawa, C B Netterfield, H T Nguyen, R O'Brient, R W Ogburn, S Palladino, C Pryke, B Racine, S Richter, A Schillaci, R Schwarz, C D Sheehy, A Soliman, T St Germaine, Z K Staniszewski, B Steinbach, R V Sudiwala, G P Teply, K L Thompson, J E Tolan, C Tucker, A D Turner, C Umiltà, A G Vieregg, A Wandui, A C Weber, D V Wiebe, J Willmert, C L Wong, W L K Wu, H Yang, K W Yoon, C Zhang
We present results from an analysis of all data taken by the bicep2/Keck CMB polarization experiments up to and including the 2015 observing season. This includes the first Keck Array observations at 220 GHz and additional observations at 95 and 150 GHz. The Q and U maps reach depths of 5.2, 2.9, and 26  μK_{CMB} arcmin at 95, 150, and 220 GHz, respectively, over an effective area of ≈400 square degrees. The 220 GHz maps achieve a signal to noise on polarized dust emission approximately equal to that of Planck at 353 GHz...
November 30, 2018: Physical Review Letters
Mattia Walschaers, Supratik Sarkar, Valentina Parigi, Nicolas Treps
Graph states are the backbone of measurement-based continuous-variable quantum computation. However, experimental realizations of these states induce Gaussian measurement statistics for the field quadratures, which poses a barrier to obtain a genuine quantum advantage. In this Letter, we propose mode-selective photon addition and subtraction as viable and experimentally feasible pathways to introduce non-Gaussian features in such continuous-variable graph states. In particular, we investigate how the non-Gaussian properties spread among the vertices of the graph, which allows us to show the degree of control that is achievable in this approach...
November 30, 2018: Physical Review Letters
Xuekai Ma, Stefan Schumacher
Vortices are topological objects formed in coherent nonlinear systems. As such they are studied in a wide number of physical systems and promise applications in information storage, processing, and communication. In semiconductor microcavities, vortices in polariton condensates can be conveniently created, studied, and manipulated using solely optical means. For nonresonant excitation with a ring-shaped pump a stable vortex can be formed, leading to bistability with left- and right-handed vorticity. In the present work we report on a much richer vortex multistability, with optically addressable vortices with topological charges m=±1, ±2, and ±3, all stable for the same system and excitation parameters...
November 30, 2018: Physical Review Letters
Jenny Feige, Anton Wallner, Randolf Altmeyer, L Keith Fifield, Robin Golser, Silke Merchel, Georg Rugel, Peter Steier, Stephen G Tims, Stephan R Winkler
We searched for the presence of ^{26}Al in deep-sea sediments as a signature of supernova influx. Our data show an exponential dependence of ^{26}Al with the sample age that is fully compatible with radioactive decay of terrigenic ^{26}Al. The same set of samples demonstrated a clear supernova ^{60}Fe signal between 1.7 and 3.2 Myr ago. Combining our ^{26}Al data with the recently reported ^{60}Fe data results in a lower limit of 0.18_{-0.08}^{+0.15} for the local interstellar ^{60}Fe/^{26}Al isotope ratio...
November 30, 2018: Physical Review Letters
Jee Woo Park, Bumsuk Ko, Y Shin
We study the critical vortex shedding in a strongly interacting fermionic superfluid of ^{6}Li across the BEC-BCS crossover. By moving an optical obstacle in the sample and directly imaging the vortices after the time of flight, the critical velocity u_{vor} for vortex shedding is measured as a function of the obstacle travel distance L. The observed u_{vor} increases with decreasing L, where the rate of increase is the highest in the unitary regime. In the deep Bose-Einstein condensation regime, an empirical dissipation model well captures the dependence of u_{vor} on L, characterized by a constant value of η=-[d(1/u_{vor})/d(1/L)]...
November 30, 2018: Physical Review Letters
Kun Jiang, Xianxin Wu, Jiangping Hu, Ziqiang Wang
We study the electronic structure and superconductivity in a CuO_{2} monolayer grown recently on the d-wave cuprate superconductor Bi_{2}Sr_{2}CaCu_{2}O_{8+δ}. Density functional theory calculations indicate a significant charge transfer across the interface such that the CuO_{2} monolayer is heavily overdoped into the hole-rich regime yet inaccessible in bulk cuprates. We show that both the Cu d_{x^{2}-y^{2}} and d_{3z^{2}-r^{2}} orbitals become important and the Fermi surface contains one electron and one hole pocket associated with the two orbitals, respectively...
November 30, 2018: Physical Review Letters
Bahadur Singh, Barun Ghosh, Chenliang Su, Hsin Lin, Amit Agarwal, Arun Bansil
Materials with tunable charge and lattice degrees of freedom provide excellent platforms for investigating multiple phases that can be controlled via external stimuli. We show how the charge-ordered ferroelectric oxide Ag_{2}BiO_{3}, which has been realized experimentally, presents a unique exemplar of a metal-insulator transition under an external electric field. Our first-principles calculations, combined with a symmetry analysis, reveal the presence of a nearly ideal hourglass-Dirac-semimetal state in the nonpolar structure of Ag_{2}BiO_{3}...
November 30, 2018: Physical Review Letters
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"