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

]]>The Meissner effect, which explains the levitation of magnetic objects, involves the expulsion of external magnetic flux from a superconductor. Now, researchers show that the inverse effect can also occur in which external magnetic flux is amplified.

[Phys. Rev. X 5, 041021] Published Fri Nov 06, 2015

]]>Superconducting qubit experiments cannot be conducted without nonreciprocal devices such as circulators and directional amplifiers. Researchers show that both of these kinds of devices can be realized using a single Josephson circuit.

[Phys. Rev. X 5, 041020] Published Thu Nov 05, 2015

]]>Superconducting cuprates are of great interest in condensed-matter physics, and now a new study shows that another transition-metal oxide, Sr${}_{2}$IrO${}_{4}$, may be analogous to cuprates in its high-temperature superconductivity.

[Phys. Rev. X 5, 041018] Published Wed Nov 04, 2015

]]>Many of tomorrow’s photonic devices, including optical biosensors, may rely on light signals with highly particular polarization properties. A new experiment shows that an ultrathin layer of gold particles can selectively absorb or reflect a light beam depending on its polarization handedness.

[Phys. Rev. X 5, 041019] Published Wed Nov 04, 2015

]]>Previous studies have shown that single nuclear spins and nuclear spin pairs can be detected. Scientists analyze time-periodic sensing protocols using Floquet theory, a powerful new method for relating experimental features to the characteristics of the detected spin or small cluster of spins.

[Phys. Rev. X 5, 041016] Published Fri Oct 30, 2015

]]>Because photons interact weakly with themselves and experience low decoherence, they are a promising avenue for quantum information science. Theorists show how the temporal modes of single-photon states can form an alphabet for communication across a quantum information network.

[Phys. Rev. X 5, 041017] Published Fri Oct 30, 2015

]]>Particle interference is a critical component of optical quantum computing and communication. Now, researchers examine multiphoton quantum interference both theoretically and experimentally by manipulating the distinguishability of photons.

[Phys. Rev. X 5, 041015] Published Tue Oct 27, 2015

]]>High-resolution tracking of the population abundances in a simple, closed microbial ecosystem shows that the intrinsic dynamics of the system are strongly deterministic.

[Phys. Rev. X 5, 041014] Published Mon Oct 26, 2015

]]>High-temperature superconductivity—the property of zero electrical resistance at relatively high temperature—is manifested in very limited classes of materials. An examination of the unique relationship between electronic structures and lattice structural units of the two known classes of high-temperature superconductors helps to identify possible new classes of these materials.

[Phys. Rev. X 5, 041012] Published Fri Oct 23, 2015

]]>Exotic excitations known as anyons are found in fractional quantum Hall states. Now, a systematic method establishes that certain symmetric theories of anyons cannot be realized in two dimensions.

[Phys. Rev. X 5, 041013] Published Fri Oct 23, 2015

]]>Quantum effects such as coherence and entanglement increase a system’s ability to store energy.

[Phys. Rev. X 5, 041011] Published Thu Oct 22, 2015

]]>Secure cryptography has been a long-standing goal of quantum applications. Now, researchers experimentally show how a quantum setup can transmit a pattern of 1s and 0s over a 25-km optical fiber by interfering two independent lasers.

[Phys. Rev. X 5, 041009] Published Wed Oct 21, 2015

]]>Quantum technology that enables two distant parties to securely communicate is of great interest in cryptography. New research shows how implementations of quantum key distribution can be significantly simplified by not co-transmitting a local oscillator reference between the two communicating parties.

[Phys. Rev. X 5, 041010] Published Wed Oct 21, 2015

]]>Quantum key distribution, a process employed in encrypted transactions, relies on Einstein-Podolsky-Rosen steering when one party has untrusted devices. For the first time, a formal framework of steering as a physical resource is presented.

[Phys. Rev. X 5, 041008] Published Thu Oct 15, 2015

]]>A theoretical analysis quantifies the technical resources required to build a quantum computer based on photons.

[Phys. Rev. X 5, 041007] Published Wed Oct 14, 2015

]]>The evolution of an isolated quantum system has applications in many fields of atomic physics, condensed matter physics, and cosmology. A theoretical study shows how an ensemble of interacting quantum spins exhibits different relaxation dynamics depending on the energy of the prepared initial states.

[Phys. Rev. X 5, 041005] Published Mon Oct 12, 2015

]]>Quantum states play key roles in advanced cryptographic methods. Now, experiments show that quantum state tomography can be optimized by employing certain mathematical constructions.

[Phys. Rev. X 5, 041006] Published Mon Oct 12, 2015

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