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Condense matter

Peng Xue, Xian Zhan, Zhihao Bian
We experimentally demonstrate a photonic quantum simulator: by using a two-spin Ising chain (an isolated dimer) as an example, we encode the wavefunction of the ground state with a pair of entangled photons. The effect of magnetic fields, leading to a critical modification of the correlation between two spins, can be simulated by just local operations. With the ratio of simulated magnetic fields and coupling strength increasing, the ground state of the system changes from a product state to an entangled state and back to another product state...
May 19, 2017: Scientific Reports
Steve M Young, Benjamin J Wieder
Filling-enforced Dirac semimetals, or those required at specific fillings by the combination of crystalline and time-reversal symmetries, have been proposed in numerous materials. However, Dirac points in these materials are not generally robust against breaking or modifying time-reversal symmetry. We present a new class of two-dimensional Dirac semimetal protected by the combination of crystal symmetries and a special, antiferromagnetic time-reversal symmetry. Systems in this class of magnetic layer groups, while having broken time-reversal symmetry, still respect the operation of time-reversal followed by a half-lattice translation...
May 5, 2017: Physical Review Letters
Alireza Taghizadeh, Il-Sug Chung
Photon's effective mass is an important parameter of an optical cavity mode, which determines the strength of light-matter interaction. Here, we propose a novel method for controlling the photon's effective mass by using coupled photonic cavities and designing the angular dependence of the coupling strength. This can be implemented by employing a high-contrast grating (HCG) as the coupling reflector in a system of two coupled vertical cavities, and engineering both the HCG reflection phase and amplitude response...
May 18, 2017: Scientific Reports
Thomas Schweigler, Valentin Kasper, Sebastian Erne, Igor Mazets, Bernhard Rauer, Federica Cataldini, Tim Langen, Thomas Gasenzer, Jürgen Berges, Jörg Schmiedmayer
Quantum systems can be characterized by their correlations. Higher-order (larger than second order) correlations, and the ways in which they can be decomposed into correlations of lower order, provide important information about the system, its structure, its interactions and its complexity. The measurement of such correlation functions is therefore an essential tool for reading, verifying and characterizing quantum simulations. Although higher-order correlation functions are frequently used in theoretical calculations, so far mainly correlations up to second order have been studied experimentally...
May 17, 2017: Nature
Gufei Zhang, Tomas Samuely, Zheng Xu, Johanna K Jochum, Alexander Volodin, Shengqiang Zhou, Paul W May, Oleksandr Onufriienko, Jozef Kačmarčík, Julian A Steele, Jun Li, Johan Vanacken, Jiri Vacík, Pavol Szabó, Haifeng Yuan, Maarten B J Roeffaers, Dorin Cerbu, Peter Samuely, Johan Hofkens, Victor V Moshchalkov
Superconductivity and ferromagnetism are two mutually antagonistic states in condensed matter. Research on the interplay between these two competing orderings sheds light not only on the cause of various quantum phenomena in strongly correlated systems but also on the general mechanism of superconductivity. Here we report on the observation of the electronic entanglement between superconducting and ferromagnetic states in hydrogenated boron-doped nanodiamond films, which have a superconducting transition temperature Tc ~ 3 K and a Curie temperature TCurie > 400 K...
May 16, 2017: ACS Nano
Jean-Philippe Tetienne, Nikolai Dontschuk, David A Broadway, Alastair Stacey, David A Simpson, Lloyd C L Hollenberg
Since its first discovery in 2004, graphene has been found to host a plethora of unusual electronic transport phenomena, making it a fascinating system for fundamental studies in condensed matter physics as well as offering tremendous opportunities for future electronic and sensing devices. Typically, electronic transport in graphene has been investigated via resistivity measurements; however, these measurements are generally blind to spatial information critical to observing and studying landmark transport phenomena in real space and in realistic imperfect devices...
April 2017: Science Advances
Mario Santoro, Federico A Gorelli, Roberto Bini, Julien Haines
Molecular nitrogen is a benchmark system for condensed matter and, in particular, for looking at universal properties of strongly confined dense systems. We conducted Raman and X-ray diffraction measurements on a dense and disordered form of molecular nitrogen subnanoconfined in a noncatalytic pure SiO2 zeolite under pressure, up to 50 GPa. In this form, N2-N2 interactions and, consequently, distances are found to be very close to those of bulk N2 and intramolecular interactions progressively weaken upon increasing pressure...
May 15, 2017: Journal of Physical Chemistry Letters
Z Zhu, R D McDonald, A Shekhter, B J Ramshaw, K A Modic, F F Balakirev, N Harrison
The excitonic insulator phase has long been predicted to form in proximity to a band gap opening in the underlying band structure. The character of the pairing is conjectured to crossover from weak (BCS-like) to strong coupling (BEC-like) as the underlying band structure is tuned from the metallic to the insulating side of the gap opening. Here we report the high-magnetic field phase diagram of graphite to exhibit just such a crossover. By way of comprehensive angle-resolved magnetoresistance measurements, we demonstrate that the underlying band gap opening occurs inside the magnetic field-induced phase, paving the way for a systematic study of the BCS-BEC-like crossover by means of conventional condensed matter probes...
May 4, 2017: Scientific Reports
Guoqing Chang, Su-Yang Xu, Shin-Ming Huang, Daniel S Sanchez, Chuang-Han Hsu, Guang Bian, Zhi-Ming Yu, Ilya Belopolski, Nasser Alidoust, Hao Zheng, Tay-Rong Chang, Horng-Tay Jeng, Shengyuan A Yang, Titus Neupert, Hsin Lin, M Zahid Hasan
Topological metals and semimetals (TMs) have recently drawn significant interest. These materials give rise to condensed matter realizations of many important concepts in high-energy physics, leading to wide-ranging protected properties in transport and spectroscopic experiments. It has been well-established that the known TMs can be classified by the dimensionality of the topologically protected band degeneracies. While Weyl and Dirac semimetals feature zero-dimensional points, the band crossing of nodal-line semimetals forms a one-dimensional closed loop...
May 10, 2017: Scientific Reports
Shao-Kai Jian, Chien-Hung Lin, Joseph Maciejko, Hong Yao
Supersymmetric (SUSY) gauge theories such as the minimal supersymmetric standard model play a fundamental role in modern particle physics, but have not been verified so far in nature. Here, we show that a SUSY gauge theory with dynamical gauge bosons and fermionic gauginos emerges naturally at the pair-density-wave (PDW) quantum phase transition on the surface of a correlated topological insulator hosting three Dirac cones, such as the topological Kondo insulator SmB_{6}. At the quantum tricritical point between the surface Dirac semimetal and nematic PDW phases, three massless bosonic Cooper pair fields emerge as the superpartners of three massless surface Dirac fermions...
April 21, 2017: Physical Review Letters
Tao Hong, Y Qiu, M Matsumoto, D A Tennant, K Coester, K P Schmidt, F F Awwadi, M M Turnbull, H Agrawal, A L Chernyshev
The notion of a quasiparticle, such as a phonon, a roton or a magnon, is used in modern condensed matter physics to describe an elementary collective excitation. The intrinsic zero-temperature magnon damping in quantum spin systems can be driven by the interaction of the one-magnon states and multi-magnon continuum. However, detailed experimental studies on this quantum many-body effect induced by an applied magnetic field are rare. Here we present a high-resolution neutron scattering study in high fields on an S=1/2 antiferromagnet C9H18N2CuBr4...
May 5, 2017: Nature Communications
Carolin Rösch, Dirk K Wissenbach, Ulrich Franck, Manfred Wendisch, Uwe Schlink
In indoor air, terpene-ozone reactions can form secondary organic aerosols (SOA) in a transient process. 'Real world' measurements conducted in a furnished room without air conditioning were modelled involving the indoor background of airborne particulate matter, outdoor ozone infiltrated by natural ventilation, repeated transient limonene evaporations, and different subsequent ventilation regimes. For the given setup, we disentangled the development of nucleated, coagulated, and condensed SOA fractions in the indoor air and calculated the time dependence of the aerosol mass fraction (AMF) by means of a process model...
April 26, 2017: Environmental Pollution
J-J Kim, S H Joo, K S Lee, J H Yoo, M S Park, J S Kwak, Jinho Lee
The Low Temperature Scanning Tunneling Microscope (LT-STM) is an extremely valuable tool not only in surface science but also in condensed matter physics. For years, numerous new ideas have been adopted to perfect LT-STM performances-Ultra-Low Vibration (ULV) laboratory and the rigid STM head design are among them. Here, we present three improvements for the design of the ULV laboratory and the LT-STM: tip treatment stage, sample cleaving stage, and vibration isolation system. The improved tip treatment stage enables us to perform field emission for the purpose of tip treatment in situ without exchanging samples, while our enhanced sample cleaving stage allows us to cleave samples at low temperature in a vacuum without optical access by a simple pressing motion...
April 2017: Review of Scientific Instruments
Daniele Vigolo, Jianguo Zhao, Stephan Handschin, Xiaobao Cao, Andrew J deMello, Raffaele Mezzenga
The isotropic and nematic (I + N) coexistence for rod-like colloids is a signature of the first-order thermodynamics nature of this phase transition. However, in the case of amyloid fibrils, the biphasic region is too small to be experimentally detected, due to their extremely high aspect ratio. Herein, we study the thermophoretic behaviour of fluorescently labelled β-lactoglobulin amyloid fibrils by inducing a temperature gradient across a microfluidic channel. We discover that fibrils accumulate towards the hot side of the channel at the temperature range studied, thus presenting a negative Soret coefficient...
April 27, 2017: Scientific Reports
Jason H V Nguyen, De Luo, Randall G Hulet
Nonlinear systems can exhibit a rich set of dynamics that are inherently sensitive to their initial conditions. One such example is modulational instability, which is believed to be one of the most prevalent instabilities in nature. By exploiting a shallow zero-crossing of a Feshbach resonance, we characterize modulational instability and its role in the formation of matter-wave soliton trains from a Bose-Einstein condensate. We examine the universal scaling laws exhibited by the system and, through real-time imaging, address a long-standing question of whether the solitons in trains are created with effectively repulsive nearest-neighbor interactions or rather evolve into such a structure...
April 28, 2017: Science
Ling-Na Wu, Xin-Yu Luo, Zhi-Fang Xu, Masahito Ueda, Ruquan Wang, L You
Spin-orbit coupling (SOC) plays an essential role in many exotic and interesting phenomena in condensed matter physics. In neutral-atom-based quantum simulations, synthetic SOC constitutes a key enabling element. The strength of SOC realized so far is limited by various reasons or constraints. This work reports tunable SOC synthesized with a gradient magnetic field (GMF) for atoms in a harmonic trap. Nearly ten-fold enhancement is observed when the GMF is modulated near the harmonic-trap resonance in comparison with the free-space situation...
April 27, 2017: Scientific Reports
Shuang Zhou, Sergij V Shiyanovskii, Heung-Shik Park, Oleg D Lavrentovich
The detailed structure of singularities of ordered field represents a fundamental problem in diverse areas of physics. At the defect cores, the deformations are so strong that the system explores states with symmetry different from that of an undistorted material. These regions are difficult to explore experimentally as their spatial extension is very small, a few molecular lengths in the condensed matter. Here we explore the cores of disclinations in the so-called chromonic nematics that extend over macroscopic length scales accessible for optical characterization...
April 21, 2017: Nature Communications
E M García, N Cherry, B D Lambert, J P Muir, M A Nazareno, J I Arroquy
BACKGROUND: Tropical tree or shrub leaves are an important source of nutrients for ruminants and a potential source of biologically active compounds that may affect ruminal metabolism of nutrients. Therefore, eight woody species from the native flora of Argentinean Dry Chaco - rich in secondary compounds such as condensed tannins (CT), were assessed for their nutritional value, CT fractions, and in vitro true digestibility of dry matter as well as biological activity (BA). RESULTS: Differences among species were found in contents of total phenol, protein-precipitating phenols (PPP), bound proteins to PPP (BP) and BP/PPP (P<0...
April 18, 2017: Journal of the Science of Food and Agriculture
Weiwei Jin, Yang Jiao, Lufeng Liu, Ye Yuan, Shuixiang Li
An ellipsoid, the simplest nonspherical shape, has been extensively used as a model for elongated building blocks for a wide spectrum of molecular, colloidal, and granular systems. Yet the densest packing of congruent hard ellipsoids, which is intimately related to the high-density phase of many condensed matter systems, is still an open problem. We discover an unusual family of dense crystalline packings of self-dual ellipsoids (ratios of the semiaxes α:sqrt[α]:1), containing 24 particles with a quasi-square-triangular (SQ-TR) tiling arrangement in the fundamental cell...
March 2017: Physical Review. E
Zhiwei Fan, Yuhan Shi, Yan Liu, Wei Pang, Yongyao Li, Boris A Malomed
We consider a dipolar Bose-Einstein condensate trapped in an array of two-well systems with an arbitrary orientation of the dipoles relative to the system's axis. The system can be built as a chain of local traps sliced into two parallel lattices by a repelling laser sheet. It is modeled by a pair of coupled discrete Gross-Pitaevskii equations, with dipole-dipole self-interactions and cross interactions. When the dipoles are not polarized perpendicular or parallel to the lattice, the cross interaction is asymmetric, replacing the familiar symmetric two-component discrete solitons by two new species of cross-symmetric ones, viz...
March 2017: Physical Review. E
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