Featured
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Perspective |
Opportunities in nanoscale probing of laser-driven phase transitions
Optical near-field microscopy has facilitated our understanding of nanophotonics. This Perspective explores the opportunities that near-field studies of terahertz fields provide for ultrafast phase transitions in condensed matter systems.
- Michael Yannai
- , Matan Haller
- & Ido Kaminer
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Article
| Open AccessAssessment of the errors of high-fidelity two-qubit gates in silicon quantum dots
For solid-state qubits, the material environment hosts sources of errors that vary in time and space. This systematic analysis of errors affecting high-fidelity two-qubit gates in silicon can inform the design of large-scale quantum computers.
- Tuomo Tanttu
- , Wee Han Lim
- & Andrew S. Dzurak
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Research Briefing |
Undetectable electrons in solids with two pairs of sublattices
Angle-resolved photoemission spectroscopy measurements identify dark electron states in palladium diselenide, cuprate superconductors, and lead halide perovskites. These dark states are attributed to the two pairs of sublattices in each of the solids, which leads to a double two-level quantum system in which double destructive interference can occur.
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Article |
Dark states of electrons in a quantum system with two pairs of sublattices
The identification of dark statesâquantum states that do not interact with photonsâin real materials may help to address many unsolved issues in condensed-matter physics. Now, they have been identified in palladium diselenide.
- Yoonah Chung
- , Minsu Kim
- & Keun Su Kim
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Research Briefing |
Collective motion of electrons captured at the atomic scale
Many 2D or 1D materials feature fascinating collective behaviour of electrons that competes with highly localized interactions at atomic defects. By combining terahertz spectroscopy with scanning tunnelling microscopy, the ultrafast motion of these collective states can be captured with atomic spatial resolution, enabling the observation of electron dynamics at their intrinsic length and time scale.
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Review Article |
Electronic excitations at the plasmonâmolecule interface
Plasmonic excitations can enhance the interaction between a metal and molecules adsorbed onto its surface. This Review summarizes the different effects involved in this process and places them into a framework based on electron scattering.
- Andrei Stefancu
- , Naomi J. Halas
- & Emiliano Cortes
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Article
| Open AccessTerahertz spectroscopy of collective charge density wave dynamics at the atomic scale
The observation of phase modes of charge density wave has been a long-standing challenge. Such low-energy phase excitations have now been seen in a transition metal dichalcogenide.
- Shaoxiang Sheng
- , Mohamad Abdo
- & Sebastian Loth
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Article
| Open AccessInduced superconducting correlations in a quantum anomalous Hall insulator
The superconducting proximity effect has not been experimentally demonstrated in a quantum anomalous Hall insulator. Now this effect is observed in the chiral edge state of a ferromagnetic topological insulator.
- Anjana Uday
- , Gertjan Lippertz
- & Yoichi Ando
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Research Briefing |
Revealing the complex phases of rhombohedral trilayer graphene
Rhombohedral graphene is an emerging material with a rich correlated-electron phenomenology, including superconductivity. The magnetism of symmetry-broken trilayer graphene has now been explored, revealing important details of the physics and providing a roadmap for broader explorations of rhombohedral graphene.
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News & Views |
Hole spins somersault in a CMOS quantum computer
The rotation of holes jumping between quantum dots in silicon quantum computers creates additional complexity for two-qubit operations. Understanding the rules of this somersaulting movement is key to the progress of hole-based qubit technology.
- Andre Saraiva
- & Dimitrie Culcer
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Article |
Bending rigidity, sound propagation and ripples in flat graphene
The mechanism by which two-dimensional materials remain stable at a finite temperature is still under debate. Now, numerical calculations suggest that rotational symmetry is crucial in suppressing anharmonic effects that lead to structural instability.
- Unai Aseginolaza
- , Josu Diego
- & Ion Errea
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Research Briefing |
Rotational symmetry influences the mechanical properties of graphene
Rotational symmetry is shown to protect the quadratic dispersion of out-of-plane flexural vibrations in graphene and other two-dimensional materials against phononâphonon interactions, making the bending rigidity of these materials non-divergent. The quadratic dispersion is then consistent with the propagation of sound in the graphene plane.
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Article
| Open AccessAnisotropic exchange interaction of two hole-spin qubits
A successful silicon spin qubit design should be rapidly scalable by benefiting from industrial transistor technology. This investigation of exchange interactions between two FinFET qubits provides a guide to implementing two-qubit gates for hole spins.
- Simon Geyer
- , Bence Hetényi
- & Andreas V. Kuhlmann
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Article
| Open AccessLeggett modes in a Dirac semimetal
Leggett modes can occur when superconductivity arises in more than one band in a material and represent oscillation of the relative phases of the two superconducting condensates. Now, this mode is observed in Cd3As2, a Dirac semimetal.
- Joseph J. Cuozzo
- , W. Yu
- & Enrico Rossi
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Article |
Manipulation of chiral interface states in a moiré quantum anomalous Hall insulator
The local electronic structure of interface states between topologically distinct domains is imaged and controlled, allowing visualization of the interplay between strong interactions and non-trivial topology.
- Canxun Zhang
- , Tiancong Zhu
- & Michael F. Crommie
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Article
| Open AccessDipolar skyrmions and antiskyrmions of arbitrary topological charge at room temperature
Control over magnetic skyrmions at room temperature has important applications in technology. Now the observation of skyrmions with high topological charge widens the potential for them to be used in unconventional computing techniques.
- Mariam Hassan
- , Sabri Koraltan
- & Manfred Albrecht
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Article
| Open AccessLong-lived valley states in bilayer graphene quantum dots
Using the valley degree of freedom in analogy to spin to encode qubits could be advantageous as many of the known decoherence mechanisms do not apply. Now long relaxation times are demonstrated for valley qubits in bilayer graphene quantum dots.
- Rebekka Garreis
- , Chuyao Tong
- & Wei Wister Huang
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Article |
Room-temperature long-range ferromagnetic order in a confined molecular monolayer
Realizing robust ferromagnetic order in two dimensions is challenging as an underlying crystalline framework is normally required. Now room-temperature ferromagnetism is demonstrated in a two-dimensional honeycomb self-assembly of confined molecules.
- Yuhua Liu
- , Haifeng Lv
- & Yi Xie
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Research Briefing |
Optical trapping and tailoring of exciton-polariton condensates into macroscopic complexes
Subwavelength photonic gratings can host long-lived, negative-effective-mass photonic modes that couple strongly to electron transitions in constituent active materials. The resulting bosonic hybrid lightâmatter modes, or exciton-polaritons, can be optically configured to accumulate into various macroscopic artificial complexes and lattices of coherent quantum fluids.
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Article |
Reconfigurable quantum fluid molecules of bound states in the continuum
Bound states in the continuum are topological states with useful symmetry protection properties. An experiment now shows how to use them to form macroscopically coherent complexes of polariton condensates.
- Antonio Gianfrate
- , Helgi Sigurðsson
- & Daniele Sanvitto
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World View |
Strategies for multidisciplinary research
Invest in fostering a culture of collaboration to help break down barriers between disciplines.
- Teresa Sanchis
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Matters Arising |
Clarification of braiding statistics in FabryâPerot interferometry
- Nicholas Read
- & Sankar Das Sarma
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News & Views |
When excitons crystallize
Semiconducting dipolar excitons â bound states of electrons and holes â in artificial moiré lattices constitute a promising condensed matter system to explore the phase diagram of strongly interacting bosonic particles.
- Nadine Leisgang
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Article |
Electron charge qubit with 0.1âmillisecond coherence time
Individual electrons trapped on the surface of solid neon can operate as charge qubits with very long coherence times.
- Xianjing Zhou
- , Xinhao Li
- & Dafei Jin
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Article |
Evidence for spinarons in Co adatoms
Despite the theoretical prediction of spinaron quasiparticles in artificial nanostructures, experimental evidence has not yet been seen. Now it has been observed in a hybrid system comprising Co atoms on a Cu(111) surface.
- Felix Friedrich
- , Artem Odobesko
- & Matthias Bode
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News & Views |
Spatial correlations of charge noise captured
Measurements of two neighbouring silicon-based qubits show that the charge noise they each experience is correlated, suggesting a common origin. Understanding these correlations is crucial for performing error correction in these systems.
- Åukasz CywiÅski
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Article |
Noise-correlation spectrum for a pair of spin qubits in silicon
Errors in a quantum computer that are correlated between different qubits pose a considerable challenge for correction schemes. Measurements of noise in silicon spin qubits show that electric field fluctuations can create strongly correlated errors.
- J. Yoneda
- , J. S. Rojas-Arias
- & S. Tarucha
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Article
| Open AccessEvidence of finite-momentum pairing in a centrosymmetric bilayer
Cooper pairs that form with finite centre-of-mass momentum are rare. Now there is evidence that this can happen below the Pauli limit in a bilayer material.
- Dong Zhao
- , Lukas Debbeler
- & Jurgen Smet
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News & Views |
A macroscopic oscillator goes and stays quantum
A milestone for the coherence time of a macroscopic mechanical oscillator may be a crucial advance for enabling the development of quantum technologies based on optomechanical architectures and for fundamental tests of quantum mechanics.
- A. Metelmann
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Article |
A squeezed mechanical oscillator with millisecond quantum decoherence
Achieving low decoherence is challenging in hybrid quantum systems. A superconducting-circuit-based optomechanical platform realizes millisecond-scale quantum state lifetime, which allows tracking of the free evolution of a squeezed mechanical state.
- Amir Youssefi
- , Shingo Kono
- & Tobias J. Kippenberg
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Article |
Josephson diode effect derived from short-range coherent coupling
The behaviour of a superconductor can be altered by changing its symmetry properties. Coherently coupling two Josephson junctions breaks time-reversal and inversion symmetries, giving rise to a device with a controllable superconducting diode effect.
- Sadashige Matsuo
- , Takaya Imoto
- & Seigo Tarucha
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Article |
Quadrature nonreciprocity in bosonic networks without breaking time-reversal symmetry
Across platforms, nonreciprocity requires time-reversal symmetry to be broken. Interference of an excitation-preserving and a non-preserving interaction realizes unidirectional transport in a time-reversal-symmetric system.
- Clara C. Wanjura
- , Jesse J. Slim
- & Andreas Nunnenkamp
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Research Briefing |
Long-lifetime phonons converse with microwave photons
A coherent interface between a mechanical oscillator and superconducting electrical circuits would enable the control of quantum states of mechanical motion, but such interfaces often result in excess mechanical energy loss. A new material-agnostic approach is shown to achieve strong electromechanical coupling while preserving a long phonon lifetime.
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Article
| Open AccessCoulomb-correlated electron number states in a transmission electron microscope beam
Coulomb interactions in free-electron beams are usually seen as an adverse effect. The creation of distinctive number states with one, two, three and four electrons now reveals unexpected opportunities for electron microscopy and lithography from Coulomb correlations.
- Rudolf Haindl
- , Armin Feist
- & Claus Ropers
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Article |
A quantum electromechanical interface for long-lived phonons
Electrical control of quantum mechanical oscillators is normally performed using piezoelectrics, but incorporating these additional materials can severely reduce performance. Electrostatic control has now been demonstrated in a silicon device.
- Alkim Bozkurt
- , Han Zhao
- & Mohammad Mirhosseini
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Article
| Open AccessNonlinear nanomechanical resonators approaching the quantum ground state
Although mechanical resonators are routinely cooled to their quantum ground state, it has remained unclear if sizable nonlinearities could persist there. Experiments in the ultrastrong-coupling regime now show that this is possible.
- C. Samanta
- , S. L. De Bonis
- & A. Bachtold
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News & Views |
Noncollinear spin textures with a twist
Generating and controlling noncollinear spin textures is a promising route towards developing next-generation logic architectures beyond CMOS. Now, these spin textures can be engineered in twisted magnetic two-dimensional materials.
- Bevin Huang
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Article |
Direct manipulation of a superconducting spin qubit strongly coupled to a transmon qubit
Semiconductor qubits can benefit from existing industrial methods, but there are challenges in coupling qubits together. A hybrid superconductorâsemiconductor qubit that couples to superconducting qubit devices may overcome these issues.
- Marta Pita-Vidal
- , Arno Bargerbos
- & Christian Kraglund Andersen
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Article |
Evidence of non-collinear spin texture in magnetic moiré superlattices
A moiré potential may play a role in determining the magnetic properties of a two-dimensional homo or heterostructure. Now, non-collinear spin structures are observed in twisted double bilayer CrI3, providing a platform to engineer unusual magnetic textures.
- Hongchao Xie
- , Xiangpeng Luo
- & Liuyan Zhao
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Article
| Open AccessPhotonic metamaterial analogue of a continuous time crystal
So far, a continuous time crystal has only been implemented on a quantum system. Optically driven many-body interactions in a nanomechanical photonic metamaterial now allow the realization of a classical continuous time crystal.
- Tongjun Liu
- , Jun-Yu Ou
- & Nikolay I. Zheludev
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Article |
Thermalization and dynamics of high-energy quasiparticles in a superconducting nanowire
The performance of superconducting devices is affected by the generation and relaxation of excitations called quasiparticles. A scanning tunnelling microscope can controllably inject quasiparticles so their dynamics can be better understood.
- T. Jalabert
- , E. F. C. Driessen
- & C. Chapelier
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News & Views |
Steps towards current metrology
Two superconductors connected by a weak link form a Josephson junction, a nonlinear circuit element at the heart of many quantum devices. Quantized electrical current steps that were predicted decades ago have now been observed experimentally.
- Gianluca Rastelli
- & Ioan M. Pop
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Article
| Open AccessPhase-locked photonâelectron interaction without a laser
Ultrafast photonâelectron spectroscopy commonly requires a driving laser. Now, an inverse approach based on cathodoluminescence spectroscopy has allowed a compact solution to spectral interferometry inside an electron microscope, without a laser.
- Masoud Taleb
- , Mario Hentschel
- & Nahid Talebi
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Article |
Storage of mechanical energy in DNA nanorobotics using molecular torsion springs
The molecular joint of a nanorobotic arm can be wound up to store mechanical energy and then relaxed to drive the rotation of a DNA nanodevice.
- Matthias Vogt
- , Martin Langecker
- & Jonathan List
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News & Views |
Non-sticky interactions
Quantum mechanical fluctuations of the electromagnetic field in a vacuum between two close together objects result in an attractive force. Now, it has been experimentally shown that by exploiting a similar repulsive interaction, attraction between objects can be modulated simply by tuning temperature.
- Victoria Esteso Carrizo
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Research Briefing |
Identifying the quantum fingerprint of plasmon polaritons
Coherent multidimensional spectroscopy with nanoscale spatial resolution was used to directly probe a plasmon polariton quantum wave packet. To reproduce these results an improved quantum model of photoemission was required, in which the coherent coupling between plasmons and electrons is accounted for with the plasmon excitations extending beyond a two-level model.
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Letter |
Detection of a plasmon-polariton quantum wave packet
Plasmonics allows precise engineering of lightâmatter interactions and is the driver behind many optical devices. The local observation of a plasmonic quantum wave packet is a step towards bringing these functionalities to the quantum regime.
- Sebastian Pres
- , Bernhard Huber
- & Tobias Brixner