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Letter |
Experimental realization and characterization of an electronic Lieb lattice
Individual carbon monoxide molecules on a copper surface can be manipulated with scanning tunnelling microscopy to realize an electronic Lieb lattice.
- Marlou R. Slot
- , Thomas S. Gardenier
- & Ingmar Swart
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Letter |
Subatomic-scale force vector mapping above a Ge(001) dimer using bimodal atomic force microscopy
Measuring vector quantities in nanoscale systems is challenging — often only scalar magnitudes can be experimentally obtained. Now, a multi-frequency atomic force microscopy method for probing the 3D force response of a Ge(001) surface is reported.
- Yoshitaka Naitoh
- , Robert Turanský
- & Yasuhiro Sugawara
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Letter |
Plasmon-enhanced high-harmonic generation from silicon
High-harmonic emission from crystalline silicon can be made ten times brighter by exploiting local plasmonic fields in arrays of nano-antennas.
- G. Vampa
- , B. G. Ghamsari
- & P. B. Corkum
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Letter |
Topological states in engineered atomic lattices
Individual vacancies in a chlorine monolayer on copper can be manipulated with scanning tunnelling microscopy to engineer artificial lattices that have topologically nontrivial electronic states.
- Robert Drost
- , Teemu Ojanen
- & Peter Liljeroth
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Letter |
Signatures of interaction-induced helical gaps in nanowire quantum point contacts
Signatures of spin–momentum-locked gap states in nanowire quantum point contacts that have all-electrical origin could provide the conditions for the quasiparticle excitations required for topological quantum computing.
- S. Heedt
- , N. Traverso Ziani
- & Th. Schäpers
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Article |
Electron–hole exchange blockade and memory-less recombination in photoexcited films of colloidal quantum dots
Understanding the recombination dynamics in quantum dots is crucial for their use in optoelectronic devices. A photocurrent spectroscopy study shows how two distinct relaxation mechanisms are at play over different timescales.
- Andrew F. Fidler
- , Jianbo Gao
- & Victor I. Klimov
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Letter |
Signatures of two-photon pulses from a quantum two-level system
An excited two-level system emits a single photon, but in special circumstances it can emit two. The reason for this unexpected two-photon emission lies with modified Rabi oscillations.
- Kevin A. Fischer
- , Lukas Hanschke
- & Kai Müller
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Letter |
Optical-field-controlled photoemission from plasmonic nanoparticles
Photoemission is usually driven by the energy of the illuminating laser pulses, but in the strong-field regime, the photoemission from an array of plasmonic nanoparticles is shown to be controlled by the light’s electric field.
- William P. Putnam
- , Richard G. Hobbs
- & Franz X. Kärtner
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Article |
Control of the millisecond spin lifetime of an electrically probed atom
Single atoms on a surface can be useful in spintronics applications, but their spin lifetime is limited by relaxation. By cleverly employing an STM tip, one can probe the spin dynamics and disentangle different effects leading to relaxation.
- William Paul
- , Kai Yang
- & Andreas J. Heinrich
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Letter |
Cooperatively enhanced dipole forces from artificial atoms in trapped nanodiamonds
The strength of optical trapping of a nanodiamond can be increased by cooperative effects between its numerous colour centres — or artificial atoms: an observation that brings together ideas from atom and nanoparticle trapping.
- Mathieu L. Juan
- , Carlo Bradac
- & Thomas Volz
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Article |
Long-range mutual synchronization of spin Hall nano-oscillators
The synchronization of nine nanoconstriction spin Hall nano-oscillators brings spin-based oscillators closer to the power and noise requirements needed for practical applications.
- A. A. Awad
- , P. Dürrenfeld
- & J. Åkerman
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Article |
Control of spin–orbit torques through crystal symmetry in WTe2/ferromagnet bilayers
A link between crystalline symmetry and the allowed symmetries of spin–orbit torques provides a route for manipulating magnetic devices with perpendicular anisotropy.
- D. MacNeill
- , G. M. Stiehl
- & D. C. Ralph
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Letter |
Interlayer electron–phonon coupling in WSe2/hBN heterostructures
The emergence of optically silent phonons show that strong interlayer electron–phonon coupling can arise in van der Waals heterostructures, with the vibrational modes in one layer coupling to the electronic states in a neighbouring layer.
- Chenhao Jin
- , Jonghwan Kim
- & Feng Wang
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Letter |
Ultrastrong coupling of a single artificial atom to an electromagnetic continuum in the nonperturbative regime
A superconducting artificial atom coupled to a 1D waveguide tests the limits of light–matter interaction in an unexplored coupling regime, which may enable new perspectives for quantum technologies.
- P. Forn-Díaz
- , J. J. García-Ripoll
- & A. Lupascu
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Letter |
Optical manipulation of valley pseudospin
Valleys in momentum space provide a degree of freedom that could be exploited for applications. A demonstration of valley pseudospin control now completes the generation–manipulation–detection paradigm, paving the way for valleytronic devices.
- Ziliang Ye
- , Dezheng Sun
- & Tony F. Heinz
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Letter |
Ramsey-type phase control of free-electron beams
Using a technique inspired by Ramsey spectroscopy it is now possible to coherently control free electrons in an electron microscope.
- Katharina E. Echternkamp
- , Armin Feist
- & Claus Ropers
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Letter |
Elastic instability-mediated actuation by a supra-molecular polymer
The elastic energy built up during peptide self-assembly is exploited in the realization of a microactuator. The energy stored is released on millisecond timescales via a buckling instability controlled with droplet microfluidics.
- Aviad Levin
- , Thomas C. T. Michaels
- & Tuomas P. J. Knowles
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News & Views |
Graphene traps
Although Dirac fermions in graphene can tunnel through potential barriers without reflection, two experiments show how they can temporarily be trapped inside nanoscale graphene quantum dots.
- Heejun Yang
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News & Views |
Heavy going
Chiral symmetry breaking is imaged in graphene which, through a mechanism analogous to mass generation in quantum electrodynamics, could provide a means for making it semiconducting.
- Christopher Mudry
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Article |
Imaging chiral symmetry breaking from Kekulé bond order in graphene
Scanning tunnelling microscopy shows how the interaction between electrons in graphene and atomic vacancies in a copper substrate produces Kekulé ordering — an electronic phase that breaks chiral symmetry.
- Christopher Gutiérrez
- , Cheol-Joo Kim
- & Abhay N. Pasupathy
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Letter |
Josephson ϕ0-junction in nanowire quantum dots
A so-called Josephson ϕ0-junction based on a nanowire quantum dot is reported. By means of electrostatic gating, it is possible to controllably introduce a phase offset taking any value between 0 and π in the ground state of the junction.
- D. B. Szombati
- , S. Nadj-Perge
- & L. P. Kouwenhoven
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Letter |
Atomic spin-chain realization of a model for quantum criticality
Magnetic adatoms offer an appealing platform for building idealized spin models, but achieving sufficient control to do so is challenging. Now, arrays of Co atoms evaporated on a Cu2N/Cu(100) surface are shown to behave like a spin-1/2 XXZ Heisenberg chain.
- R. Toskovic
- , R. van den Berg
- & A. F. Otte
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Letter |
Charge density wave order in 1D mirror twin boundaries of single-layer MoSe2
A scanning tunnelling microscopy study demonstrates that one-dimensional charge density waves can form at twin boundaries in a monolayer transition metal dichalcogenide.
- Sara Barja
- , Sebastian Wickenburg
- & Alexander Weber-Bargioni
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Article |
Direct measurement of the propagation velocity of defects using coherent X-rays
Defects affect materials’ properties. A method is now presented for studying dynamic processes during the growth of thin films — specifically, the evolution of defects — based on the coherent mixing of bulk and surface X-ray scattering signals.
- Jeffrey G. Ulbrandt
- , Meliha G. Rainville
- & Randall L. Headrick
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Letter |
Few-second-long correlation times in a quantum dot nuclear spin bath probed by frequency-comb nuclear magnetic resonance spectroscopy
Using a frequency-comb nuclear magnetic resonance spectroscopy technique it is possible to probe the fluctuations in the nuclear spin bath of a self-assembled quantum dot and reveal long nuclear spin correlation times over one second.
- A. M. Waeber
- , M. Hopkinson
- & E. A. Chekhovich
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Letter |
Collective magnetic response of CeO2 nanoparticles
The magnetic response of nanoparticles made from wide-bandgap oxides that don’t contain any magnetic cations is somewhat of a mystery. Experiments with CeO2 suggest that the origin may be due to vacuum fluctuations.
- Michael Coey
- , Karl Ackland
- & Siddhartha Sen
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Letter |
Realization of a tunable artificial atom at a supercritically charged vacancy in graphene
Single carbon vacancies in graphene can host a positive charge that is tunable. When this charge is large enough such vacancies resemble artificial atoms, with an induced sequence of quasi-bound states that trap nearby electrons.
- Jinhai Mao
- , Yuhang Jiang
- & Eva Y. Andrei
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Letter |
Electron viscosity, current vortices and negative nonlocal resistance in graphene
In analogy to fluids, electric currents can exhibit viscosity — albeit with effects difficult to observe experimentally. Now, vorticity is reported as a signature feature of electron viscosity in graphene, which leads to negative nonlocal resistance.
- Leonid Levitov
- & Gregory Falkovich
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Letter |
Quantum-limited heat conduction over macroscopic distances
Quantum mechanics sets a fundamental upper limit for the flow of heat. Such quantum-limited heat conduction is now observed over macroscopic distances, extending to a metre, in superconducting transmission lines.
- Matti Partanen
- , Kuan Yen Tan
- & Mikko Möttönen
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Letter |
Quantum oscillations of the critical current and high-field superconducting proximity in ballistic graphene
Josephson junctions based on graphene exhibit tunable proximity effects. The appearance of superconducting states when changing magnetic field and carrier concentration has now been investigated—some proximity effect survives for fields above 1 T.
- M. Ben Shalom
- , M. J. Zhu
- & J. R. Prance
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Letter |
Adiabatic spin-transfer-torque-induced domain wall creep in a magnetic metal
The creep motion of domain walls in magnetic metals can belong to different universality classes depending on whether they are driven by magnetic fields or spin-polarized currents.
- S. DuttaGupta
- , S. Fukami
- & H. Ohno
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Letter |
Specular interband Andreev reflections at van der Waals interfaces between graphene and NbSe2
Andreev reflection occurs at the interface of a metal and a superconductor when an incident electron in the metal gets ‘reflected’ as a hole travelling on the same path. Replace the metal with graphene and specular reflection may instead take place.
- D. K. Efetov
- , L. Wang
- & P. Kim
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Letter |
Modulation of mechanical resonance by chemical potential oscillation in graphene
By coupling to electrons in the quantum Hall regime, the mechanical response of graphene resonators is modulated by changes in the chemical potential.
- Changyao Chen
- , Vikram V. Deshpande
- & James Hone
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News & Views |
Could use a break
Electric fields can controllably break the inversion symmetry of bilayer graphene, which can be harnessed to generate pure valley currents.
- François Amet
- & Gleb Finkelstein
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Letter |
Universality of non-equilibrium fluctuations in strongly correlated quantum liquids
Quantum liquids at equilibrium follow Fermi liquid theory, but less is known about non-equilibrium conditions. Carbon nanotubes, which exhibit universal scaling behaviour, provide a testbed for many-body physics beyond equilibrium.
- Meydi Ferrier
- , Tomonori Arakawa
- & Kensuke Kobayashi
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Letter |
Generation and detection of pure valley current by electrically induced Berry curvature in bilayer graphene
Bilayer graphene can host topological currents that are robust against defects and are associated with the electron valleys. It is now shown that electric fields can tune this topological valley transport over long distances at room temperature.
- Y. Shimazaki
- , M. Yamamoto
- & S. Tarucha
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Letter |
Spatially resolved edge currents and guided-wave electronic states in graphene
Experiments show that electron waves can be confined to and guided along the edges of monolayer and bilayer graphene sheets, analogous to the guiding of light waves in optical fibres.
- M. T. Allen
- , O. Shtanko
- & A. Yacoby
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News & Views |
Turn the other way
Negative refraction can produce optical Veselago lenses with a resolution that is not diffraction-limited. Similar lenses can also be made for electrons, with negative refraction of Dirac fermions now shown in graphene.
- Péter Makk
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Article |
Resonant tunnelling between the chiral Landau states of twisted graphene lattices
For small twist angles, electrons can resonantly tunnel between graphene layers in a van der Waals heterostructure. It is now shown that the tunnelling not only preserves energy and momentum, but also the chirality of electronic states.
- M. T. Greenaway
- , E. E. Vdovin
- & L. Eaves
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Letter |
Coherent long-range magnetic bound states in a superconductor
Magnetic atoms embedded in a niobium selenide superconductor are shown to give rise to a long-range coherent bound state extending tens of nanometres.
- Gerbold C. Ménard
- , Sébastien Guissart
- & Tristan Cren
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Letter |
Gate-tunable topological valley transport in bilayer graphene
Bilayer graphene can host topological currents that are robust against defects and are associated with the electron valleys. It is now shown that electric fields can tune this topological valley transport over long distances at room temperature.
- Mengqiao Sui
- , Guorui Chen
- & Yuanbo Zhang
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Letter |
Three-stage decoherence dynamics of an electron spin qubit in an optically active quantum dot
The mechanisms of decoherence in solid-state spin qubits subject to low magnetic fields turn out to be more complex than previously expected as an additional fast relaxation stage has now been identified.
- Alexander Bechtold
- , Dominik Rauch
- & Jonathan J. Finley
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Observation of negative refraction of Dirac fermions in graphene
Negative refraction has now been observed for Dirac fermions in graphene, and is used to create an electronic Veselago lens.
- Gil-Ho Lee
- , Geon-Hyoung Park
- & Hu-Jong Lee
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Letter |
Parity lifetime of bound states in a proximitized semiconductor nanowire
Bound states in semiconductor–superconductor hybrids are shown to have parity lifetimes of over 10 milliseconds, suggesting that they could provide a platform for topological quantum computing.
- A. P. Higginbotham
- , S. M. Albrecht
- & C. M. Marcus
Solid-state platforms
A trap for two