Featured
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News & Views |
Noisy fractions
Fractional charges are one of the hallmarks of topological matter and the building blocks of various topological devices. Now, there are indications that their fingerprint in terms of electrical noise is less obvious, but more universal, than expected.
- Stefano Roddaro
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Article |
Evidence for a spinon Kondo effect in cobalt atoms on single-layer 1T-TaSe2
Unconventional quasiparticles carrying spin but not electric charge emerge in quantum spin liquid phases. The Kondo interaction of these spinon quasiparticles with magnetic impurities may now have been observed.
- Yi Chen
- , Wen-Yu He
- & Michael F. Crommie
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Letter |
Experiments with levitated force sensor challenge theories of dark energy
In experiments with a levitated force sensor, no signatures of a fifth force are detected. This rules out the basic chameleon model, which is a popular theory providing an explanation for dark energy.
- Peiran Yin
- , Rui Li
- & Jiangfeng Du
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Article
| Open AccessJosephson diode effect from Cooper pair momentum in a topological semimetal
A diode effect—asymmetric transport depending on its direction—is shown in the proximity-induced superconducting state of a Dirac semimetal.
- Banabir Pal
- , Anirban Chakraborty
- & Stuart S. P. Parkin
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News & Views |
Magnetic skyrmions unwrapped
Experiments with chiral magnets may hold the key to a better understanding of fundamental aspects of transformations between different skyrmionic states, necessary for magnetic memory and logic applications to become a reality.
- Alexey A. Kovalev
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Letter |
Excitonic insulator in a heterojunction moiré superlattice
Stacking monolayer WS2 on top of bilayer WSe2 creates conditions where electrons and holes can coexist in the structure. Their Coulomb interaction allows them to form bound pairs and hence an excitonic insulator state.
- Dongxue Chen
- , Zhen Lian
- & Su-Fei Shi
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Article |
Correlated interlayer exciton insulator in heterostructures of monolayer WSe2 and moiré WS2/WSe2
When independent layers of electrons and holes are in close proximity to each other, their Coulomb interaction allows them to pair into neutral bosons and form an insulating state. This phenomenon is reported in a heterostructure of 2D materials.
- Zuocheng Zhang
- , Emma C. Regan
- & Feng Wang
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Article |
Sustained unidirectional rotation of a self-organized DNA rotor on a nanopore
A self-assembled DNA structure is coupled to a nanopore and exhibits continuous rotation in the presence of nanoscale flows driven by electric fields or ionic gradients.
- Xin Shi
- , Anna-Katharina Pumm
- & Cees Dekker
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Article
| Open AccessSuperconducting quantum interference at the atomic scale
Continuously changing the coupling between a magnetic impurity and a superconductor allows the observation of the reversal of supercurrent flow at the atomic scale.
- Sujoy Karan
- , Haonan Huang
- & Christian R. Ast
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News & Views |
Harmonic generation in confinement
Quantum confinement effects offer a more comprehensive understanding of the fundamental processes that drive extreme optical nonlinearities in nano-engineered solids, opening a route to unlocking the potential of high-order harmonic generation.
- Julien Madéo
- & Keshav M. Dani
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Letter |
Size-controlled quantum dots reveal the impact of intraband transitions on high-order harmonic generation in solids
Both inter- and intraband transitions contribute to high-harmonic generation in solids, but their exact roles are not fully understood. Experiments with quantum dots show that enhanced intraband transitions lead to increased carrier injection and thus enhanced harmonic generation.
- Kotaro Nakagawa
- , Hideki Hirori
- & Yoshihiko Kanemitsu
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Letter
| Open AccessSkyrmion–antiskyrmion pair creation and annihilation in a cubic chiral magnet
Magnetic skyrmions—a type of localized spin texture—have been theoretically predicted to annihilate with counterparts known as antiskyrmions. By means of electron microscopy, such annihilation has now been observed in a cubic chiral magnet.
- Fengshan Zheng
- , Nikolai S. Kiselev
- & Rafal E. Dunin-Borkowski
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Measure for Measure |
The new kilogram for new technology
The shift of the definition of the kilogram in 2019 away from an artefact to one relying on the Planck constant inspires technological innovation, as Naoki Kuramoto elucidates.
- Naoki Kuramoto
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News & Views |
Quantum echoes
Quantum waves can have stronger correlations than classical ones because of their particle nature. This effect has now been observed using quantum sound waves travelling in an acoustic waveguide.
- H. Yamaguchi
- & D. Hatanaka
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Article |
Non-classical mechanical states guided in a phononic waveguide
Non-classical vibrations are generated and transmitted along a mechanical waveguide, providing a platform for distributing quantum information and realizing hybrid quantum devices using phonons in a solid-state system.
- Amirparsa Zivari
- , Robert Stockill
- & Simon Gröblacher
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Letter |
Berry curvature dipole senses topological transition in a moiré superlattice
Transport experiments highlight a technique to detect transitions in the topological state of two-dimensional materials, with possible applications in memory devices.
- Subhajit Sinha
- , Pratap Chandra Adak
- & Mandar M. Deshmukh
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Article |
Correlated Hofstadter spectrum and flavour phase diagram in magic-angle twisted bilayer graphene
In graphene, the spin and valley degrees of freedom combine into a higher-order isospin. Now, a full map of the phase diagram of this isospin is measured in the moiré bands of twisted bilayer graphene.
- Jiachen Yu
- , Benjamin A. Foutty
- & Benjamin E. Feldman
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Article |
Interaction-driven giant thermopower in magic-angle twisted bilayer graphene
Thermal transport measurements provide a complementary view of the electronic structure of a material to electronic transport. This technique is applied to twisted bilayer graphene, and highlights the particle–hole asymmetry of its band structure.
- Arup Kumar Paul
- , Ayan Ghosh
- & Anindya Das
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Letter |
Thermal superconducting quantum interference proximity transistor
Heat transport in electronic systems is influenced by nearby superconductors due to the so-called proximity effect. Combining this with the manipulation of superconductivity using magnetic fields enables the control of nanoscale thermal transport.
- Nadia Ligato
- , Federico Paolucci
- & Francesco Giazotto
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News & Views |
Encounter with a stranger metal
Low-temperature measurements on twisted bilayer graphene show that the exotic ‘strange metal’ state is almost certainly caused by interactions between electrons.
- Tobias Stauber
- & José González
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News & Views |
Double trouble
Experiments show that interactions between electrons in twisted bilayer graphene can create a spatial order that doubles the size of the twisted unit cell.
- Eric Spanton
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Letter |
Broken-symmetry states at half-integer band fillings in twisted bilayer graphene
Correlated insulating states are common in twisted bilayer graphene when the density of carriers is close to an integer per moiré unit cell. Now, such states emerge at half-integer fillings and show signs of being spin or charge density waves.
- Saisab Bhowmik
- , Bhaskar Ghawri
- & U. Chandni
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Article
| Open AccessBand transport by large Fröhlich polarons in MXenes
The charge transport mechanism in MXenes—an emerging class of layered materials—is not yet fully understood. A combination of terahertz spectroscopy and transport measurements shows that the formation of large polarons play a crucial role.
- Wenhao Zheng
- , Boya Sun
- & Mischa Bonn
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Letter |
Direct observation of a dynamical glass transition in a nanomagnetic artificial Hopfield network
A spin glass is a disordered system with randomized competing magnetic interactions. Now, a metamaterial artificial spin glass based on nanomagnets is reported, with rudimentary features of a neural network.
- Michael Saccone
- , Francesco Caravelli
- & Alan Farhan
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Article |
Strained crystalline nanomechanical resonators with quality factors above 10 billion
Soft clamping reduces the dissipation of nanomechanical resonators, but this method has been limited to amorphous materials. When applied in crystalline silicon, it enables resonators with quality factors beyond ten billion.
- A. Beccari
- , D. A. Visani
- & T. J. Kippenberg
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News & Views |
Clock qubit conducts nuclear ensemble
A rare-earth ion in a long-lived clock state can control a nearby ensemble of nuclear spins. Interfacing this pristine photon emitter with a small quantum processor may be a route towards making identical solid-state nodes for quantum networks.
- Claire Le Gall
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Article |
Cyclotron resonance overtones and near-field magnetoabsorption via terahertz Bernstein modes in graphene
Electrons in an external magnetic field absorb electromagnetic radiation via cyclotron resonance. Deviations from this behaviour in the form of overtone resonances due to ultraslow magnetoplasmonic excitations are now reported for graphene.
- D. A. Bandurin
- , E. Mönch
- & S. D. Ganichev
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News & Views |
Optical energy on demand
Light travels through disordered media on a random path that is hard to control. A comprehensive study has now shown that optical energy can be deposited at a desired depth in a disordered waveguide by injecting a light field with a particular shape.
- Oluwafemi S. Ojambati
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Letter |
Bulk and edge properties of twisted double bilayer graphene
Twisted double bilayer graphene is predicted to be a topological insulator under certain conditions. Simultaneous bulk and edge measurements now show metallic transport with a bulk bandgap, suggestive of this prediction.
- Yimeng Wang
- , Jonah Herzog-Arbeitman
- & Emanuel Tutuc
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News & Views |
To measure a magnon population
Magnons are collective spin excitations that can propagate over long distances — an attractive trait for information-transfer technologies — but we need to better understand their thermodynamic properties. A platform using graphene may hold the key.
- Matteo Carrega
- & Stefan Heun
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Letter
| Open AccessThermodynamics of free and bound magnons in graphene
Although magnons in the quantum Hall regime of graphene have been detected, their thermodynamic properties have not yet been measured. Now, a local probe technique enables the detection of the magnon density and chemical potential.
- Andrew T. Pierce
- , Yonglong Xie
- & Amir Yacoby
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News & Views |
A layered unconventional superconductor
Most systems exhibiting topological superconductivity are artificial structures that require precise engineering. Now, a layered material shows tantalizing signs of the phenomenon.
- Jose L. Lado
- & Peter Liljeroth
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Article |
Optomechanical interface between telecom photons and spin quantum memory
Quantum networks require a connection between quantum memories and optical links, which often operate in different frequency ranges. An optomechanical device exploiting the strain dependence of a colour-centre spin provides such a spin–optics interface at room temperature.
- Prasoon K. Shandilya
- , David P. Lake
- & Paul E. Barclay
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Letter |
Imaging local discharge cascades for correlated electrons in WS2/WSe2 moiré superlattices
The Hubbard model describes many fascinating phenomena, but relating it to complicated quantum materials is difficult. Now, atomic-resolution measurements can estimate the interaction parameters that appear in the model for real materials.
- Hongyuan Li
- , Shaowei Li
- & Feng Wang
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News & Views |
Quantum sensors go flat
Some material defects have quantum degrees of freedom that are measurably disturbed by environmental changes, making them excellent sensors. A two-dimensional material with such defects could improve the versatility of quantum-sensing technologies.
- J.-P. Tetienne
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Article |
Nanoscale Turing patterns in a bismuth monolayer
Macroscale patterns seen in biological systems such as animal coats or skin can be described by Turing’s reaction–diffusion theory. Now Turing patterns are shown to also exist in bismuth monolayers, an exemplary nanoscale atomic system.
- Yuki Fuseya
- , Hiroyasu Katsuno
- & Aharon Kapitulnik
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Article |
Dynamics of driven polymer transport through a nanopore
A study of the dynamics of polymer translocation through synthetic nanopores provides a direct observation of tension propagation—a non-equilibrium description of the process of unfolding that a polymer undergoes during translocation.
- Kaikai Chen
- , Ining Jou
- & Nicholas A. W. Bell
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Article |
Learning models of quantum systems from experiments
Quantum systems make it challenging to determine candidate Hamiltonians from experimental data. An automated protocol is presented and its capabilities to infer the correct Hamiltonian are demonstrated in a nitrogen-vacancy centre set-up.
- Antonio A. Gentile
- , Brian Flynn
- & Anthony Laing
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Letter |
One-dimensional Kronig–Penney superlattices at the LaAlO3/SrTiO3 interface
The two-dimensional electron gas at an oxide interface is patterned to form a channel with a periodic potential imposed on top. This replicates the textbook Kronig–Penney model and leads to fractionalization of electron bands in the channel.
- Megan Briggeman
- , Hyungwoo Lee
- & Jeremy Levy
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Comment |
Instruments of change for academic tool development
Scientific progress has always been driven by the ability to build an instrument to answer a specific question. But spreading the news of how to replicate that tool is an evolving art, ripe for an open-source revolution.
- Georg E. Fantner
- & Andrew C. Oates
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Article |
Optical polarization analogue in free electron beams
The functionality of electron energy loss spectroscopy can be extended to include a polarization analogue constructed via the dipole transition vector between two electronic states, bringing it closer to its optical counterpart.
- Hugo Lourenço-Martins
- , Davy Gérard
- & Mathieu Kociak
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News & Views |
Multitudes of twists
Multiplexing increases the capacity of optical communication, but it is limited by the number of modes and their orbital angular momentum. A robust vortex laser now solves this problem by emitting several beams, all carrying large topological charges.
- Ren-Min Ma
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Letter |
Photonic quantum Hall effect and multiplexed light sources of large orbital angular momenta
A topological photonic crystal design directly generates light that carries orbital angular momentum with high quantum numbers. The beam contains several different states at the same time, promising integrated and multiplexed light sources.
- Babak Bahari
- , Liyi Hsu
- & Boubacar Kanté
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Article |
Tunable van Hove singularities and correlated states in twisted monolayer–bilayer graphene
A structure of monolayer and bilayer graphene with a small twist between them shows correlated insulating states that can be tuned by changing the twist angle or applying an electric field.
- Shuigang Xu
- , Mohammed M. Al Ezzi
- & Yanmeng Shi
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Letter |
Non-Majorana states yield nearly quantized conductance in proximatized nanowires
Majorana bound states should appear at both ends of a nanowire if it is in the topological regime. This paper reports that, in many cases, zero-bias conduction peaks only occur on one end of the wire, which casts doubt on whether they are Majoranas.
- P. Yu
- , J. Chen
- & S. M. Frolov