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Understanding the role of phase in chemical bond breaking with coincidence angular streaking
Ultrafast laser pulses are useful to study electron dynamics in chemical bonds, but their influence on bond breaking is not fully understood. Wu et al. study H2 bond breaking with coincidence techniques, and find a phase-dependent anisotropy of the H+fragmentation even for isotropic multicycle laser pulses.
- J. Wu
- , M. Magrakvelidze
- & R. Dörner
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Spatial entanglement of bosons in optical lattices
Estimating the entanglement in a system is vital for quantum information processing, particularly in many-body systems. To this end, Cramer et al.experimentally quantify multi-partite entanglement in an optical lattice across the superfluid-Mott insulator phase transition and at different temperatures.
- M. Cramer
- , A. Bernard
- & M.B. Plenio
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Experimental realization of an optical second with strontium lattice clocks
The SI second is based on caesium microwave fountains, but optical lattice clocks show increasingly greater performances. This work presents two strontium optical lattice clocks agreeing better than their comparison to three fountains, suggesting that such clocks may realize a better definition of the second.
- R. Le Targat
- , L. Lorini
- & J. Lodewyck
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| Open AccessVibrationally induced inversion of photoelectron forward-backward asymmetry in chiral molecule photoionization by circularly polarized light
The Franck–Condon principle—frozen nuclear positions during electronic motion—is used to explain many physical phenomena. Garcia et al.show how this breaks down in a photoionized chiral molecule via the vibrational dependence of the photoelectron angular asymmetry in the laboratory frame.
- Gustavo A. Garcia
- , Laurent Nahon
- & Ivan Powis
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Engineering p-wave interactions in ultracold atoms using nanoplasmonic traps
Controlling p-wave interactions between fermions would enable studies of interesting quantum phenomena. Towards this end, Juliá-Díaz et al. propose a combination of strongly confined nanoplasmonic traps and laser-induced gauge fields that could produce the necessary coupling of atomic states.
- B. Juliá-Díaz
- , T. Graß
- & M. Lewenstein
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Atomic scale study of the life cycle of a dislocation in graphene from birth to annihilation
Dislocations are key in determining a variety of properties of crystalline materials, but are inherently difficult to study in three-dimensional structures. Here, Lehtinen et al. image the full life cycle of a dislocation in a two-dimensional graphene sheet, from birth to annihilation.
- O. Lehtinen
- , S. Kurasch
- & U. Kaiser
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Robust site-resolvable quantum gates in an optical lattice via inhomogeneous control
Ultracold atoms in optical lattices are promising for quantum information applications, but it is important to address individual sites with high accuracy and low cross-talk. Lee et al.adapt inhomogeneous control methods to improve the performance of single-qubit gates for selected sites.
- J. H. Lee
- , E. Montano
- & P. S. Jessen
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Sensitive magnetic control of ensemble nuclear spin hyperpolarization in diamond
The transfer of spin polarization from electrons to nuclei is important for nuclear spin-based techniques such as nuclear magnetic resonance. Here Wang and colleagues achieve sensitive magnetic control of the hyperpolarization of nuclei near optically polarized nitrogen-vacancy centres in diamond.
- Hai-Jing Wang
- , Chang S. Shin
- & Vikram S. Bajaj
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| Open AccessControlled formation and reflection of a bright solitary matter-wave
Bright solitary waves in Bose–Einstein condensates are analogues of solitons in conventional wave systems, and may enable interesting tests of many-body quantum systems. Using 85Rb, Marchant et al.show the controlled formation of bright solitary matter-waves, and their reflection from a repulsive barrier.
- A. L. Marchant
- , T. P. Billam
- & S. L. Cornish
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| Open AccessMeasurement of the first ionization potential of astatine by laser ionization spectroscopy
The application of astatine, one of the rarest elements on the earth, in the treatment of cancer requires a better understanding of its chemistry. Rothe et al. report the first measurement of the ionization potential of astatine, against which high-level quantum calculations are benchmarked.
- S. Rothe
- , A. N. Andreyev
- & K. D. A. Wendt
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Suppression of population transport and control of exciton distributions by entangled photons
The unusual properties of entangled photons endow them with useful properties for imaging and metrology tasks. This work simulates the use of entangled photons for controlling two-exciton states in Blastochloris viridis, showing their advantages for studying excitation pathways in bacterial reaction centres.
- Frank Schlawin
- , Konstantin E. Dorfman
- & Shaul Mukamel
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| Open AccessDescription and first application of a new technique to measure the gravitational mass of antihydrogen
One intriguing question about antimatter that is yet to be directly answered is whether or not it behaves exactly the same as matter under gravity. Here, a direct experimental method is presented to measure the ratio of inertial to gravitational mass for antihydrogen under free-fall conditions.
- C. Amole
- , M. D. Ashkezari
- & A. E. Charman
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Solid-state electronic spin coherence time approaching one second
Nitrogen-vacancy centres in diamond are a promising route for solid-state quantum information processing and magnetometry, but longer coherence times are needed to optimize protocols. Here, Bar-Gill et al. suppress decoherence to realize nitrogen-vacancy spin coherence times approaching one second.
- N. Bar-Gill
- , L.M. Pham
- & R.L. Walsworth
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| Open AccessRelativistic electron mirrors from nanoscale foils for coherent frequency upshift to the extreme ultraviolet
By reflecting light from a relativistically moving mirror, its frequency can be changed, which could create X-rays from visible light. Kiefer et al. make such a mirror from relativistic electrons formed by an intense laser striking a nanofoil, and shift a laser pulse from the infrared to the extreme ultraviolet.
- D. Kiefer
- , M. Yeung
- & B. Dromey
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High-coherence electron bunches produced by femtosecond photoionization
Ultrashort electron bunches are promising for diffraction measurements of structural dynamics, particularly in surfaces, thin films or membrane proteins. With this goal in mind, Engelen et al.generate high-coherence ultrafast electron bunches by photoionisation of laser-cooled atoms.
- W. J. Engelen
- , M. A. van der Heijden
- & O. J. Luiten
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High-coherence picosecond electron bunches from cold atoms
Ultrashort electron bunches are promising for diffractive imaging measurements of structural dynamics, particularly in small or delicate structures. To this end, McCulloch et al. use a two-colour photoionization process to generate high-coherence ultrafast electron bunches from laser-cooled atoms.
- A. J. McCulloch
- , D. V. Sheludko
- & R. E. Scholten
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Direct visualization of reversible dynamics in a Si6 cluster embedded in a graphene pore
Studying the structural dynamics of clusters of just a handful of atoms is challenging. But by imaging a cluster of six silicon atoms trapped in a pore of a sheet of graphene with an electron microscope, Lee et al. observe the reversible switching of the cluster between different metastable structural states.
- Jaekwang Lee
- , Wu Zhou
- & Sokrates T. Pantelides
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X-ray observation of a helium atom and placing a nitrogen atom inside He@C60 and He@C70
Helium has not, to date, been observed crystallographically. Here, the authors report the first crystallographic observation of a helium atom, encapsulated in a fullerene, and show that it exerts a small but detectable influence on the electronic structure of a coencapsulated nitrogen atom.
- Yuta Morinaka
- , Satoru Sato
- & Yasujiro Murata
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| Open AccessNanoscale light–matter interactions in atomic cladding waveguides
Alkali vapours are increasingly useful in photonic research and metrology applications, and they provide a useful test bed for investigating light–matter interaction. Stern et al. integrate silicon nitride waveguides with alkali vapours to study light–matter interactions on a chip-scale platform.
- Liron Stern
- , Boris Desiatov
- & Uriel Levy
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Topological states in a ladder-like optical lattice containing ultracold atoms in higher orbital bands
Arrays of ultracold gas atoms trapped in an optical lattice can mimic many of the behaviours of conventional matter and give rise to exotic quantum states of matter as well. Li et al. suggest that a system of atoms in a two-legged ladder-like lattice could exhibit topological insulator and topological superconductor states.
- Xiaopeng Li
- , Erhai Zhao
- & W. Vincent Liu
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| Open AccessSi:P as a laboratory analogue for hydrogen on high magnetic field white dwarf stars
Measuring atomic spectra in high magnetic fields is important for understanding astrophysical objects such as white dwarfs, but laboratory fields are too small to do so. Murdin et al. study the analogous spectra of phosphorous-doped silicon, whose material properties scale the equivalent field to far lower values.
- B.N. Murdin
- , Juerong Li
- & P.G. Murdin
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Motional averaging in a superconducting qubit
One of the advantages that it is hoped quantum computers will have over classical computers is their ability to accurately simulate quantum phenomena. Silveri et al.take a step towards this goal by simulating so-called motional averaging in an artificial atom realized by a superconducting quantum bit.
- Jian Li
- , M.P. Silveri
- & G.S. Paraoanu
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Non-equilibrium dynamics of an unstable quantum pendulum explored in a spin-1 Bose–Einstein condensate
Theoretical models usually fail in describing the behaviour of a many-body quantum system at a hyperbolic fixed point—a point of unstable equilibrium analogous to a motionless inverted pendulum. Gerving et al.show that such behaviour can be explored in the non-equilibrium dynamics of a Bose condensate.
- C.S. Gerving
- , T.M. Hoang
- & M.S. Chapman
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Probing the tunnelling site of electrons in strong field enhanced ionization of molecules
Molecules in intense laser fields have enhanced multiple ionization rates, caused by the ionic core and laser fields acting on the part of the molecule in the up-field. Here, direct proof of this model is presented by studying the instantaneous effect of the field direction during double ionization in ArXe.
- J. Wu
- , M. Meckel
- & R. Dörner
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Cooling and stabilization by collisions in a mixed ion–atom system
Trapped ions and atoms coexist at different temperatures in mixed systems, and cooling of ions through collisions with atoms is required for the mixture to stabilize. Raviet al. study these effects using rubidium atoms and ions, and find a collisional cooling mechanism leading to stability of the mixture.
- K. Ravi
- , Seunghyun Lee
- & S.A. Rangwala
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| Open AccessThe elusive Heisenberg limit in quantum-enhanced metrology
Quantum metrology employs the properties of quantum states to further enhance the accuracy of some of the most precise measurement schemes to date. Here, a method for estimating the upper bounds to achievable precision in quantum-enhanced metrology protocols in the presence of decoherence is presented.
- Rafał Demkowicz-Dobrzański
- , Jan Kołodyński
- & Mădălin Guţă
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Real-space observation of spin-split molecular orbitals of adsorbed single-molecule magnets
Controlling the behaviour of single molecules on electrode interfaces is crucial for the development of molecular spintronics. This study reports spin-polarized scanning tunnelling microscopy data of the spin-split molecular orbitals of a single-molecule magnet adsorbed on a cobalt surface.
- Jörg Schwöbel
- , Yingshuang Fu
- & Roland Wiesendanger
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Electronic origin of high-temperature superconductivity in single-layer FeSe superconductor
The exact mechanism for superconductivity in iron-based superconductors remains elusive, but is thought to involve complex interactions between many orbitals. Using angle-resolved photoelectron spectroscopy, Liuet al. report the electronic structure of the single-layer parent compound FeSe.
- Defa Liu
- , Wenhao Zhang
- & X.J. Zhou
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Absorption imaging of a single atom
Absorption imaging relies on the capture of photons by an object to create intensity contrasts, allowing for the visualization of small quantum systems. Streedet al. demonstrate the first absorption imaging of an isolated ytterbium ion, with contrast at the limit of semiclassical theory.
- Erik W. Streed
- , Andreas Jechow
- & David Kielpinski
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Field-directed sputter sharpening for tailored probe materials and atomic-scale lithography
Scanning probe microscopy and related techniques rely on the availability of very sharp tips. Here, a sharpening technique based on field-directed sputtering is demonstrated, resulting in ultrasharp metallic tips for use in scanning tunnelling microscopy as well as atomic-scale lithographic experiments.
- S.W. Schmucker
- , N. Kumar
- & J.W. Lyding
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Suppression of spin-bath dynamics for improved coherence of multi-spin-qubit systems
Nitrogen-vacancy colour centres in diamond are promising examples for solid-state multi-spin-qubit systems. Here, the spin environment of nitrogen vacancy centres is studied spectroscopically, uncovering a mechanism for spin-flip suppression that opens the way for quantum information applications.
- N. Bar-Gill
- , L.M. Pham
- & R. Walsworth
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| Open AccessAttosecond tracing of correlated electron-emission in non-sequential double ionization
Studying the dynamics of electrons is important for understanding fundamental processes in materials. Here the ionization of a pair of electrons in argon atoms is explored on attosecond timescales, offering insight into their correlated emission and the double ionization mechanism.
- Boris Bergues
- , Matthias Kübel
- & Matthias F. Kling
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Scalable architecture for a room temperature solid-state quantum information processor
Electron spins at nitrogen-vacancy centres in diamond are thought to be the most promising building blocks for practical realizations of quantum computers. Yaoet al. present a scalable architecture for a quantum information processor based on such vacancy centres that operates at room temperature.
- N.Y. Yao
- , L. Jiang
- & M.D. Lukin
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Electrically driven photon antibunching from a single molecule at room temperature
Single-photon emitters are important for developing quantum technologies, but their integration with existing devices requires them to be driven by electric fields. Here, an organic light-emitting diode is presented that emits single photons from guest molecules in an applied electric field at room temperature.
- Maximilian Nothaft
- , Steffen Höhla
- & Jörg Wrachtrup
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| Open AccessViolation of a Leggett–Garg inequality with ideal non-invasive measurements
Quantum mechanics predicts that objects can simultaneously exist in a superposition of two states. Kneeet al.propose and demonstrate experimentally a protocol which fully confirms this prediction, by testing the so-called Leggett–Garg inequality in a non-invasive manner.
- George C. Knee
- , Stephanie Simmons
- & Simon C. Benjamin
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| Open AccessDetecting inertial effects with airborne matter-wave interferometry
Inertial sensors using atom interferometry have applications in geophysics, navigation- and space-based tests of fundamental physics. Here, the first operation of an atom accelerometer during parabolic flights is reported, demonstrating high-resolution measurements at both 1g and 0g.
- R. Geiger
- , V. Ménoret
- & P. Bouyer
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| Open AccessFast cavity-enhanced atom detection with low noise and high fidelity
Single atoms can be detected using optical resonators that extend the lifetime of the photon. Here, the authors demonstrate fast, high-fidelity detection of very low atom densities using a microfabricated optical cavity to couple the detection light with the atoms.
- J. Goldwin
- , M. Trupke
- & E.A. Hinds
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| Open AccessFractional quantum Hall effect in the absence of Landau levels
The fractional quantum Hall effect occurs when electrons move in Landau levels. In this study, using a theoretical flat-band lattice model, the fractional quantum Hall effect is observed in the presence of repulsive interactions when the band is one third full and in the absence of Landau levels.
- D.N. Sheng
- , Zheng-Cheng Gu
- & L. Sheng
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Onset of a quantum phase transition with a trapped ion quantum simulator
A quantum simulator can follow the evolution of a prescribed model, whose behaviour may be difficult to determine. Here, the emergence of magnetism is simulated by implementing a quantum Ising model, providing a benchmark for simulations in larger systems.
- R. Islam
- , E.E. Edwards
- & C. Monroe
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Using disorder to detect locally ordered electron nematics via hysteresis
Interactions between charge, orbital and lattice degrees of freedom in correlated electron systems have resulted in predictions of new electronic phases of matter. Carlson and Dahmen propose two protocols for detecting disordered electron nematics in condensed matter systems using non-equilibrium methods.
- E.W. Carlson
- & K.A. Dahmen
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Statistically induced phase transitions and anyons in 1D optical lattices
Anyons are particles with fractional statistics that interpolate between bosons and fermions, and are thought to exist in low-dimensional systems. Keilmannet al. propose an experimental system to create anyons in one-dimensional optical lattices using assisted Raman tunnelling.
- Tassilo Keilmann
- , Simon Lanzmich
- & Marco Roncaglia
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| Open AccessTransition to a Bose–Einstein condensate and relaxation explosion of excitons at sub-Kelvin temperatures
Bose–Einstein condensation of excitons in thermal equilibrium is a predicted quantum statistical phenomenon that has been difficult to observe. Yoshiokaet al. cool trapped excitons to sub-Kelvin temperatures and show that condensation manifests itself as a relaxation explosion as has been observed for atomic hydrogen.
- Kosuke Yoshioka
- , Eunmi Chae
- & Makoto Kuwata-Gonokami
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Observation of atomic speckle and Hanbury Brown–Twiss correlations in guided matter waves
Speckle patterns are a manifestation of decoherence and can result from two-particle interference. Here, the authors image atomic speckle for guided matter waves and link this to atom bunching in the second-order correlation function, suggesting potential use in squeezed-atom interferometry applications.
- R.G. Dall
- , S.S. Hodgman
- & A.G. Truscott
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A nanomechanical interface to rapid single-molecule interactions
Single-molecule force spectroscopy is used to study single molecule interactions, but probing short-lived events is difficult. Here, a nanomechanical interface is developed, which allows the study of microsecond timescale interactions.
- Mingdong Dong
- & Ozgur Sahin
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Identification of active atomic defects in a monolayered tungsten disulphide nanoribbon
The physical and chemical properties of low-dimensional materials, such as nanoribbons, are affected by edge structures and atomic defects. Here, single-atom defects in a monolayered tungsten disulphide nanoribbon are discriminated and the motions of atomic defects are visualized.
- Zheng Liu
- , Kazu Suenaga
- & Sumio Iijima
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| Open AccessHigh efficiency coherent optical memory with warm rubidium vapour
Efficient memory systems are vital for the development of quantum communications technologies. Hosseini and colleagues describe an optical memory based on warm rubidium vapour that achieves 87% pulse recall efficiency, illustrating the potential of warm atomic vapour systems for quantum memory.
- M. Hosseini
- , B.M. Sparkes
- & B.C. Buchler
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Experimental magic state distillation for fault-tolerant quantum computing
Error correction in quantum computing can be implemented using transversal gates, which in turn rely on the availability of so-called magic states. The authors experimentally show that it is possible to improve the fidelity of these states by distilling five of them into one.
- Alexandre M. Souza
- , Jingfu Zhang
- & Raymond Laflamme
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No-go theorem for superradiant quantum phase transitions in cavity QED and counter-example in circuit QED
The authors show theoretically that in cavity quantum electrodynamics (QED), superradiant quantum phase transitions are forbidden. Conversely, for circuit QED, the quantum phase transition remains possible. This may pave the way for the study of interesting quantum phases.
- Pierre Nataf
- & Cristiano Ciuti
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Nanostructural hierarchy increases the strength of aluminium alloys
Improving the properties of metallic alloys is important to develop new lightweight materials. In this paper, we show that an aluminium (Al) alloy containing a hierarchy of nanostructures in a solid solution with a high density of dislocations is capable of beating strength records for Al alloys while maintaining good ductility.
- Peter V. Liddicoat
- , Xiao-Zhou Liao
- & Simon P. Ringer