A predicted type of atom-light crystal could host phonon-like excitations, allowing for new ways to simulate the physics of solids.

[Phys. Rev. X 6, 021026] Published Tue May 24, 2016

]]>A recently discovered class of two-dimensional semiconductors exhibits a novel degree of freedom known as valley pseudospin. New results show that a weak magnetic field can significantly extend the depolarization time of this pseudospin.

[Phys. Rev. X 6, 021024] Published Fri May 20, 2016

]]>Dilute atomic gases with tunable interactions are tools that can be used to understand many-body physics. Scientists study the interplay between two-body evaporation and three-body recombination in ultracold cesium and lithium gases.

[Phys. Rev. X 6, 021025] Published Fri May 20, 2016

]]>Motors that perform work can be powered by either a chemical fuel or time-dependent changes in their surrounding environment. A theoretical analysis shows that these two classes of motors are thermodynamically equivalent.

[Phys. Rev. X 6, 021022] Published Wed May 18, 2016

]]>Recurrent neuronal networks constitute the biological substrate of high-level brain functions such as memory and reasoning. Researchers use energy-efficient, neurally inspired hardware to show how network heterogeneity affects the dynamics of such systems.

[Phys. Rev. X 6, 021023] Published Wed May 18, 2016

]]>Collision and transport phenomena are difficult to describe in many dense, strongly interacting laboratory and astrophysical plasmas. Now, researchers experimentally study collisional dynamics in dilute plasmas of ${}^{88}$Sr ions barely one degree above absolute zero.

[Phys. Rev. X 6, 021021] Published Tue May 17, 2016

]]>The internet is filled with memes that have “gone viral.” A study of meme popularity uses an analytically tractable model that sheds light on the fundamental drivers of meme popularity in social networks.

[Phys. Rev. X 6, 021019] Published Fri May 13, 2016

]]>X-ray photons can be used as unique probes to understand the properties of elementary excitations. A theoretical study demonstrates that a complex x-ray scattering technique captures richer spectral information than simpler two-particle correlation functions in cuprate superconductors.

[Phys. Rev. X 6, 021020] Published Fri May 13, 2016

]]>In quantum mechanics, Heisenberg’s uncertainty principle prevents the determination of precise, simultaneous measurements of two quantities. A new approach extracts position and momentum information from the same group of entangled photons by dramatically undersampling the system.

[Phys. Rev. X 6, 021018] Published Thu May 12, 2016

]]>Free-space laser links have been used to synchronize optical clocks with an unprecedented uncertainty of femtoseconds.

[Phys. Rev. X 6, 021016] Published Wed May 11, 2016

]]>Topological edge states are observed inside a large band gap on the surface of ZrTe${}_{5}$ crystals, paving the way for topological quantum computing devices.

[Phys. Rev. X 6, 021017] Published Tue May 10, 2016

]]>Microwave cavities are widely used to control closed few-level systems in the context of quantum information processing. Now, they also appear as a powerful probe for quantum tunneling in hybrid nanocircuits.

[Phys. Rev. X 6, 021014] Published Mon May 09, 2016

]]>Linking the properties of a material’s bulk and surface is often challenging and limited to low-dimensional systems. Now, researchers theoretically demonstrate a bulk-boundary correspondence for a class of three-dimensional insulators, namely symmetry-protected topological phases of matter.

[Phys. Rev. X 6, 021015] Published Mon May 09, 2016

]]>Researchers discover a unique topological phase present in a periodically driven, two-dimensional system: All of its bulk Floquet states are localized by disorder while its edges support propagating chiral modes.

[Phys. Rev. X 6, 021013] Published Fri May 06, 2016

]]>[Phys. Rev. X 6, 020001] Published Wed May 04, 2016

]]>[Phys. Rev. X 6, 029902] Published Tue May 03, 2016

]]>Shining a laser onto a microscopic object coated with a superfluid film induces flows that can generate a controlled force.

[Phys. Rev. X 6, 021012] Published Fri Apr 29, 2016

]]>Understanding metastatic cell escape from tumors and embryonic development requires a detailed understanding of how cells move collectively inside dense tissues. Scientists show that small changes to single-cell behavior can cause tissue to transition between a fluidlike and a solidlike state.

[Phys. Rev. X 6, 021011] Published Thu Apr 21, 2016

]]>[Phys. Rev. X 6, 029901] Published Tue Apr 19, 2016

]]>Topological insulators combine aspects of metals, semiconductors, and insulators and also show unusual electric properties. A theoretical study reveals that they also exhibit unconventional magnetism as a result of electron transitions normally forbidden by energy conservation.

[Phys. Rev. X 6, 021010] Published Mon Apr 18, 2016

]]>Naturally occurring crystals are classified by spacetime symmetries, and now researchers theoretically expand this classification, with the aim of topologically classifying band insulators.

[Phys. Rev. X 6, 021008] Published Fri Apr 15, 2016

]]>A mathematical technique for comparing large symbol sets suggests that less frequently used words are mainly responsible for the evolution of the English language over the past two centuries.

[Phys. Rev. X 6, 021009] Published Fri Apr 15, 2016

]]>An investigation into how lipids diffuse in the presence of varying protein:lipid number ratios reveals that protein crowding results in drastically different lipid and protein diffusion due to the strengthened impact of correlated motion.

[Phys. Rev. X 6, 021006] Published Tue Apr 12, 2016

]]>Understanding the physics in multiple-state open systems is critical in many fields of physics. A study of an ensemble of connected lossy cavities shows how eigenstates can coalesce to produce new higher-order singularities.

[Phys. Rev. X 6, 021007] Published Tue Apr 12, 2016

]]>Fault-tolerant topological quantum computation has long been a goal of physicists. A theoretical proposal shows how Majorana zero modes can be used in a universal quantum computer in a manner that avoids precise timing requirements.

[Phys. Rev. X 6, 021005] Published Fri Apr 08, 2016

]]>Interactions between atomic ions and valence electrons are fundamental to the properties of all materials. A new investigation visualizes and quantifies electron-lattice interactions in aluminum heated by an infrared laser pulse.

[Phys. Rev. X 6, 021003] Published Wed Apr 06, 2016

]]>High-temperature superconductivity in cuprates is an ongoing mystery. Scientists show that two electronic phases of the cuprate La${}_{2-x}$Sr${}_{x}$CuO${}_{4}$ are in fact separate.

[Phys. Rev. X 6, 021004] Published Wed Apr 06, 2016

]]>Accurately measuring extremely small forces is important in many fields of physics, materials science, and engineering. Researchers demonstrate tiny “trampoline’’ mechanical sensors that are exquisitely sensitive to attonewton forces at room temperature.

[Phys. Rev. X 6, 021001] Published Fri Apr 01, 2016

]]>Modern society is permeated by systems with many numbers of nodes and connections (e.g., rail networks, airports). A theoretical study of the multiplex network consisting of European Union air routes and the London rail transportation system demonstrates the fragility of such a network.

[Phys. Rev. X 6, 021002] Published Fri Apr 01, 2016

]]>An analysis of data spanning 29 orders of magnitude in gravitational-wave frequency provides insights into the physics of the early cosmos.

[Phys. Rev. X 6, 011035] Published Thu Mar 31, 2016

]]>Multiple interaction layers are a fact of life in real-world networks. Scientists model how well networks can be represented using superpositions of layers assembled using either AND or OR logic.

[Phys. Rev. X 6, 011036] Published Thu Mar 31, 2016

]]>Studies of molecular motors and their cargo moving within cells have revealed that they can be trapped for long periods of times. Researchers show that this trapping can occur when the motors encounter intersections of cytoskeletal filaments within cells.

[Phys. Rev. X 6, 011037] Published Thu Mar 31, 2016

]]>A variety of linelike structures in orientationally ordered materials are identified by researchers as umbilic lines, a natural set of geometric singularities that reveal the topological structure of these materials.

[Phys. Rev. X 6, 011033] Published Mon Mar 28, 2016

]]>$U(1)$ quantum spin liquids represent quantum phases of matter associated with different electric and magnetic particles. A theoretical study shows how these phases can be distinguished in the presence of time-reversal symmetry.

[Phys. Rev. X 6, 011034] Published Mon Mar 28, 2016

]]>Light-mediated interactions are commonplace in both the laboratory and nature, and now researchers show how to harness them to generate and sustain large-scale quantum entanglement in extended networks of qubits.

[Phys. Rev. X 6, 011032] Published Wed Mar 23, 2016

]]>A new quantum device uses a superconducting circuit to monitor a 2D gas of electrons floating on the surface of superfluid helium.

[Phys. Rev. X 6, 011031] Published Mon Mar 21, 2016

]]>The metal-insulator transition is an important aspect of quantum mechanics. Using lattice models populated with Dirac electrons, researchers present a numerically exact investigation of this transition.

[Phys. Rev. X 6, 011029] Published Thu Mar 17, 2016

]]>Natural systems such as the brain and the heart can occasionally switch to harmful patterns. Now, researchers suggest a new mechanism for these changes with the goal of better predicting what modulates pattern switchings.

[Phys. Rev. X 6, 011030] Published Thu Mar 17, 2016

]]>An electric field can launch shock waves that create a fast and nonvolatile resistivity change in transition-metal oxides.

[Phys. Rev. X 6, 011028] Published Tue Mar 15, 2016

]]>Simulations show that the interface between two perovskite oxides can be a much stronger ferroelectric than either oxide on its own.

[Phys. Rev. X 6, 011027] Published Mon Mar 14, 2016

]]>The emission from a polariton laser shows the coherence that is common to conventional lasers, a step toward using them as high-efficiency alternative light sources.

[Phys. Rev. X 6, 011026] Published Fri Mar 11, 2016

]]>The frequency of a laser based on trapped ultracold atoms can be made insensitive to fluctuations in the laser cavity’s length.

[Phys. Rev. X 6, 011025] Published Wed Mar 09, 2016

]]>Unconditionally secure communication between remote parties has many applications in finance and industry. Now, a quantum key distribution network spread over a metropolitan area is shown to be secure against untrustworthy relays.

[Phys. Rev. X 6, 011024] Published Fri Mar 04, 2016

]]>Error correction by feedback is crucial in quantum computation, and an experiment now shows that two such methods can be integrated in a nested feedback protocol to obtain the best properties of both.

[Phys. Rev. X 6, 011022] Published Thu Mar 03, 2016

]]>String breaking refers to flux strings breaking, resulting in the production of particle-antiparticle pairs. Now, investigators quantitatively analyze the real-time evolution of string breaking and study the growth of the system entanglement.

[Phys. Rev. X 6, 011023] Published Thu Mar 03, 2016

]]>Drawing inferences from data is at the heart of many fields of science. A new kind of data analysis, free of assumptions from underlying models, is proposed and its use demonstrated on weather data.

[Phys. Rev. X 6, 011021] Published Tue Mar 01, 2016

]]>[Phys. Rev. X 6, 019902] Published Tue Mar 01, 2016

]]>Cryptographic science and lotteries both rely on the generation of random numbers. Researchers demonstrate a photonic setup that can reliably generate random numbers.

[Phys. Rev. X 6, 011020] Published Thu Feb 25, 2016

]]>Researchers study oscillating quartz crystals to search for physics not explained by the standard model, and they recover results that are 6 orders of magnitude more precise than any previous laboratory experiment.

[Phys. Rev. X 6, 011018] Published Wed Feb 24, 2016

]]>Estimating errors is a fundamental component of science. Researchers present a new framework for quantifying uncertainties associated with nuclear interactions for low-mass nuclei.

[Phys. Rev. X 6, 011019] Published Wed Feb 24, 2016

]]>Reducing the time necessary for experimental measurements allows more data to be obtained, which in turn leads to a more sensitive result. A roughly twofold speedup in differentiating between two charge states of a point defect in diamond is demonstrated, which could substantially facilitate the detection of small magnetic fields.

[Phys. Rev. X 6, 011017] Published Tue Feb 23, 2016

]]>Quasicrystals are a class of materials that exhibit long-range order but no periodicity. A study of topological transport in quasicrystals shows that, surprisingly, a two-dimensional photonic quasicrystal exhibits a topological insulating phase.

[Phys. Rev. X 6, 011016] Published Mon Feb 22, 2016

]]>Complex ensembles of multiple components are found in many biological systems, such as brains. Researchers model a population of oscillators acting like firing neurons to study the onset of irregular collective dynamics.

[Phys. Rev. X 6, 011015] Published Fri Feb 19, 2016

]]>Tests of the standard model of particle physics rely on measurements with highly polarized electron beams. A new instrument achieves the highest known precision for determining the beam polarization of low-energy (~1 GeV) electron beams.

[Phys. Rev. X 6, 011013] Published Tue Feb 16, 2016

]]>A fluid consisting of solid particles that is confined within a narrow channel undergoes changes in, for example, its thermodynamic properties. Researchers investigate the density fluctuations and isothermal compressibilities of spherical silica particles suspended in a solvent that is subjected to nanoscopic confinement.

[Phys. Rev. X 6, 011014] Published Tue Feb 16, 2016

]]>Rotation is a ubiquitous concept in physics. A new approach shows how the concept of angular momentum spread among many particles can be simplified and approximated.

[Phys. Rev. X 6, 011012] Published Fri Feb 12, 2016

]]>Foams contain suspended bubbles and are therefore susceptible to degradation over time. Scientists show how a “suit of armor” that coats individual bubbles can stabilize them.

[Phys. Rev. X 6, 011010] Published Fri Feb 05, 2016

]]>Light-emitting diodes are in widespread use in both commercial and residential settings. New research shows that applying a small magnetic field to some devices can boost their luminescence efficiency.

[Phys. Rev. X 6, 011011] Published Fri Feb 05, 2016

]]>A robot group clusters together or disperses based on each robot’s reaction time for sensing light, a finding useful for search-and-rescue missions.

[Phys. Rev. X 6, 011008] Published Fri Jan 29, 2016

]]>Double-layer capacitors can be used to harness wind and solar energy, and now new measurements reveals the electrical double-layer structure of silica-electrolyte interfaces that controls capacitance.

[Phys. Rev. X 6, 011007] Published Thu Jan 28, 2016

]]>Many biological molecules exhibit rare events such as protein folding between long-lived states. A new approach allows the kinetics of these rare events to be efficiently simulated with readily achievable computational times.

[Phys. Rev. X 6, 011009] Published Thu Jan 28, 2016

]]>[Phys. Rev. X 6, 019901] Published Thu Jan 28, 2016

]]>Cerenkov radiation is ubiquitous in a range of applications from nuclear reactors to biological imaging. New work shows that the quantum attributes of the charged particles result in important changes to the traditional Cerenkov theory.

[Phys. Rev. X 6, 011006] Published Mon Jan 25, 2016

]]>Casimir and van der Waals forces, induced by dipolar fluctuations, are commonplace, and now a new study shows that fluctuations induced by monopolar charges can create similar or stronger forces in solid-state devices.

[Phys. Rev. X 6, 011004] Published Thu Jan 21, 2016

]]>The transition that an amorphous solid undergoes to become a fluid flow is central to many real-world applications such as landslides and earthquakes. Now, researchers model the stability of amorphous solids in three and four dimensions.

[Phys. Rev. X 6, 011005] Published Thu Jan 21, 2016

]]>Ensuring efficient pedestrian streams through transit corridors such as subway hallways is a problem of significant relevance to many cities. By modeling self-driven particles, scientists show that modulating the shape of a hallway’s walls might help to separate opposite pedestrian flows.

[Phys. Rev. X 6, 011003] Published Thu Jan 07, 2016

]]>The properties of human cells are determined by their mechanical environment, which they sense when they make contact with it. A new study shows how cells adhere to surfaces presenting heterogeneous nanomechanical environments.

[Phys. Rev. X 6, 011001] Published Tue Jan 05, 2016

]]>A quantum system can jump into its ground state by emitting a photon. Now, scientists produce a superposition of ground and excited states by just measuring the emitted light.

[Phys. Rev. X 6, 011002] Published Tue Jan 05, 2016

]]>Researchers explore the limits of quantum theory using pairs of entangled photons and find results consistent with quantum predictions.

[Phys. Rev. X 5, 041052] Published Wed Dec 30, 2015

]]>Molecular nitrogen plays a role in the assembly of prebiotic molecules, and it protects humans from the Sun’s extreme ultraviolet radiation. Researchers investigate, for the first time, the ultrafast molecular dynamics of nitrogen as it disassociates.

[Phys. Rev. X 5, 041053] Published Wed Dec 30, 2015

]]>Optomechanics, which refers to the interplay of light and nanomechanics, has widespread applications in sensing and quantum optics. Researchers demonstrate that an optomechanical system based on single-crystal diamond nanobeams can undergo large self-oscillations.

[Phys. Rev. X 5, 041051] Published Tue Dec 29, 2015

]]>Conventional electric circuits use electrons as information carriers, a process that dissipates vast quantities of waste heat. A new design for a spin-wave diode, which produces no Joule heating, is presented.

[Phys. Rev. X 5, 041049] Published Mon Dec 28, 2015

]]>Novel topological phenomena are believed to arise in systems driven out of equilibrium. Now, researchers make a key step toward realizing such phenomena and establish the requirements for obtaining Floquet insulator steady states.

[Phys. Rev. X 5, 041050] Published Mon Dec 28, 2015

]]>Many-body localization leads to the breakdown of ergodicity in quantum systems and defies description in terms of equilibrium statistical mechanics. Researchers introduce an order parameter that makes it possible to probe how ergodicity and thermalization break down due to many-body localization.

[Phys. Rev. X 5, 041047] Published Wed Dec 23, 2015

]]>Two-dimensional Mott insulators allow for a remarkable “deconfined” quantum phase transition. A new theoretical and computational study shows that this controversial critical point may be even stranger than previously thought.

[Phys. Rev. X 5, 041048] Published Wed Dec 23, 2015

]]>Topological effects persist in Weyl semimetals, and now two experiments show how Fermi arcs lead to nonlocal currents in Weyl semimetal samples already at the semiclassical level.

[Phys. Rev. X 5, 041046] Published Mon Dec 21, 2015

]]>A new metamaterial acts like a cloak over a wide range of microwave frequencies.

[Phys. Rev. X 5, 041045] Published Fri Dec 18, 2015

]]>Theorists demonstrate a quantum variant of the Kolmogorov-Arnold-Moser theorem, a theorem in classical mechanics that concerns the crossover between integrability and chaos. Integrability breaking in the Lieb-Liniger model, a model describing one-dimensional Bose gases, leads to a deformation, not destruction, of the model’s conserved quantities.

[Phys. Rev. X 5, 041043] Published Wed Dec 16, 2015

]]>Correlated quantum many-body systems appear in physics, chemistry, and biology. Researchers simulate and explore such systems using an experimentally controlled superconducting quantum device.

[Phys. Rev. X 5, 041044] Published Wed Dec 16, 2015

]]>Majorana particles, which are their own antiparticles and whose recent detection in solid-state systems remains controversial, are expected to play an important role in future quantum computing. Now, scientists predict that graphene may host Majorana particles.

[Phys. Rev. X 5, 041042] Published Tue Dec 15, 2015

]]>Error correction is critical in topological quantum computation, but it restricts the quantum gates that can be easily performed. A proposed model shows how to correct errors and perform complex gates by braiding in realistic qubit systems that support non-Abelian parafermions.

[Phys. Rev. X 5, 041040] Published Mon Dec 14, 2015

]]>Modeling systems with a large number of interacting electrons is critical to understanding the physical properties of materials and molecules of interest to chemists and physicists. Researchers model a system using a range of numerical techniques and compare results in order to find sources of uncertainty and establish benchmarks.

[Phys. Rev. X 5, 041041] Published Mon Dec 14, 2015

]]>Fault-tolerant quantum computation has been a long-standing goal in many fields of physics. A new model shows how logical qubits can be encoded using anyon excitations from Majorana fermions arranged on a two-dimensional lattice.

[Phys. Rev. X 5, 041038] Published Thu Dec 10, 2015

]]>Copying information is fundamental in both nature and human industries. Researchers show how the accuracy of a simple copying process is related to thermodynamics.

[Phys. Rev. X 5, 041039] Published Thu Dec 10, 2015

]]>The act of a quantum measurement reduces the uncertainty in the motion of a vibrating membrane below the fundamental quantum limit.

[Phys. Rev. X 5, 041037] Published Mon Dec 07, 2015

]]>A proof-of-principle experiment allows single photons to travel in only one direction through an optical fiber.

[Phys. Rev. X 5, 041036] Published Fri Dec 04, 2015

]]>Theorists studying unexpected quantum states of matter show that the second-neighbor Kitaev can explain materials that are in close proximity to a spin-liquid state.

[Phys. Rev. X 5, 041035] Published Tue Dec 01, 2015

]]>Time-reversal symmetry is fundamental to condensed matter physics, and now researchers show how time reversal can be applied locally, using a tensor network representation, and how time-reversal twists can be used to detect topological order.

[Phys. Rev. X 5, 041034] Published Mon Nov 30, 2015

]]>Glasses remain a poorly understood material despite their widespread use. A study of the macroscopic elastic properties of a colloidal-glass former during vitrification offers new insights.

[Phys. Rev. X 5, 041033] Published Wed Nov 25, 2015

]]>Researchers use ideas generated in the study of quantum entanglement to guide the construction of new impurity solvers, enabling analysis of substantially more complex and realistic problems within the cluster dynamical mean-field-theory framework.

[Phys. Rev. X 5, 041032] Published Tue Nov 24, 2015

]]>Topological insulators possess properties of both conductors and insulators. A theoretical study demonstrates that the surface state of a Fu-Kane-Mele topological insulator can access all of the other surface states of the material.

[Phys. Rev. X 5, 041031] Published Fri Nov 20, 2015

]]>Chaos is a fundamental aspect of many fields of nuclear and atomic physics. Scientists use collisions among magnetic rare-earth atoms to investigate quantum chaos.

[Phys. Rev. X 5, 041029] Published Thu Nov 19, 2015

]]>Cortical neural circuits have been hypothesized to operate in a regime termed the “edge of chaos.” A new theoretical study puts this regime in a more biologically plausible perspective.

[Phys. Rev. X 5, 041030] Published Thu Nov 19, 2015

]]>The transition between a superfluid and a normal fluid in two dimensions can be understood in terms of the proliferation of topological defects. Now, scientists theoretically analyze such phase transitions in the far-from-equilibrium context of a quantum fluid of exciton polaritons.

[Phys. Rev. X 5, 041028] Published Tue Nov 17, 2015

]]>Modulating the phase of electromagnetic waves has many applications in photonic research. A new mechanism allows a thin graphene metasurface to reliably achieve an extremely large phase modulation in THz radiation.

[Phys. Rev. X 5, 041027] Published Mon Nov 16, 2015

]]>Black hole horizons have been shown to have characteristic entropies and temperatures. A new investigation shows similarities between the entropy of a black hole and a metallic state of high-temperature superconductors.

[Phys. Rev. X 5, 041025] Published Fri Nov 13, 2015

]]>Water, plasmas, and laser light can all exhibit instabilities. Experiments in two different areas of wave physics are used to investigate the creation and annihilation dynamics of superregular breather waves, which combine to form an instability.

[Phys. Rev. X 5, 041026] Published Fri Nov 13, 2015

]]>Coupling the frequency of an electromagnetic cavity to the square of mechanical displacement of the cavity structure has been proposed for realizing quantum nondemolition measurements. Such measurement systems are now one step closer with the realization of a tunable microscale photonic crystal cavity with coupling that is some 5 orders of magnitude larger than in conventional Fabry-Pérot resonators.

[Phys. Rev. X 5, 041024] Published Thu Nov 12, 2015

]]>Spintronics devices often use the accumulation of spins, probed by magnetoresistance, to convey information, and now researchers identify the origin of junction magnetoresistance in artificially engineered oxide heterostructures.

[Phys. Rev. X 5, 041023] Published Wed Nov 11, 2015

]]>Interactions between molecules and light modes can alter the chemical structures of molecules. By examining strong coupling from a microscopic perspective it is possible to predict the modifications that molecules will undergo.

[Phys. Rev. X 5, 041022] Published Mon Nov 09, 2015

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