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A transistor made from atomically thin materials mimics the way in which connections between neurons are strengthened by activity. Two perspectives reveal why physicists and neuroscientists share equal enthusiasm for this feat of engineering.

A proposed theoretical explanation for the electronic behaviour of moiré graphene is the coexistence of light and heavy electrons. Now local thermoelectric measurements hint that this model could be accurate.

Direct imaging and characterization of propagating plasmons in high-quality graphene, encapsulated between two films of hexagonal boron nitride, has now been achieved together with the observation of very low plasmon damping.

The combination of fast photo-response and high gain plays a pivotal role in photodetector devices. Here the authors combine a colloidal quantum dot photodiode with a graphene phototransistor to overcome the speed, quantum efficiency and linear dynamic range limitations of available phototransistors.

Active control of optical fields at the nanoscale is difficult to achieve. Here, the authors fabricate an on-chip graphene NEMS suspended a few tens of nanometres above nitrogen vacancy centres and demonstrate electromechanical control of the photons emitted by electrostatic tuning of the graphene NEMS position.

Exploiting the intrinsic response of magic-angle twisted bilayer graphene to resonant terahertz radiation, the interplay between electron interactions and quantum geometry is studied in such flat-band systems.

When electrons are transported through a semiconductor quantum dot, they interact with nuclear spin in the host material. This interaction—often considered to be a nuisance—is now shown to provide a feedback mechanism that actively pulls the electron-spin Larmor frequency into resonance with that of an external microwave driving field.

Graphene–quantum dots on CMOS sensor offers broadband imaging.

Graphene possesses a nonlinear optical response arising from its electronic dispersion. Here, the authors measure the response of graphene to an ultrafast optical field and provide an explanation of the quantum dynamics of Dirac carriers mediating the material’s nonlinear response.

The detection of low-energy photons may be enabled by devices that make use of the excess thermal energy from photoexcited carriers as a result of light absorption. Here the authors demonstrate a vertical graphene-WSe₂-graphene heterostructure that takes advantage of the photo-thermionic effect.

Plasmonics is heralded as the perfect symbiosis of optics, which is quick, and electronics, which works on a small scale. A method for electrically detecting plasmon polaritons using a quantum dot removes the need for far-field optical techniques and could enable nanoscale integrated circuits.

Manipulating the electrons trapped in quantum-dot pairs is seen as one possible route to quantum computation. This idea is now extended to three quantum dots, enabling a whole host of extended functionality.

The propagation of plasmons in graphene–hexagonal boron nitride moiré patterns is experimentally studied for the first time via infrared scattering near-field optical spectroscopy.

The efficiency of carrier–carrier scattering in graphene is now experimentally demonstrated. The dominance of this mechanism over phonon-related scattering means that a single high-energy photon could create two or more electron–hole pairs in graphene; an effect useful for optoelectronic applications.

Polaritons are confined hybrid light-matter excitations holding potential for optoelectronic and sensing applications, but their characterization is usually limited to optical spectroscopy. Here, the authors report the electrical spectroscopy of mid-infrared plasmon-phonon polaritons in Au/hBN/graphene nanoresonators, showing high lateral confinement and quality factors.

A phototransistor in which electric charges are absorbed by colloidal quantum dots and circulated in graphene exhibits high values for gain, responsivity and specific detectivity.

Second-order superlattices emerging in magic-angle twisted bilayer graphene aligned with hexagonal boron nitride are visualized in real space through cryogenic nano-imaging, revealing the impact of strain and twist-angle variations.

A photonic topological edge state, achieved by employing hexagonal boron nitride and patterned gold films, confines light four orders of magnitude below the diffraction limit while preserving a high quality factor.

Exploiting optical multimodal confinement, the deep-subwavelength confinement of hyperbolic phonon polaritons is demonstrated in isotopically pure hexagonal boron nitride, enabling nanoscale polariton manipulation.

Graphene grain boundaries and charge inhomogeneities limit its electronic properties. Here the authors combine scanning near-field optical microscopy with electrical read-out to image these defects at the nanoscale under an encapsulation layer, and show that charges build up along the edges of the flake.

Focused-ion beam (FIB) lithography enables high-resolution nanopatterning of 2D materials, but usually introduces significant damage. Here, the authors report a FIB-based fabrication technique to obtain high quality graphene superlattices with 18-nm pitch, which exhibit electronic transport properties similar to those of natural moiré systems.

Here, the authors use a nanoscale probe to study the photoresponse within a single moiré unit cell of minimally twisted bilayer graphene, and observe an intricate photo-thermoelectric response attributed to the Seebeck coefficient variation at AB-BA domain boundaries.

Moiré potentials substantially alter the electronic properties of twisted bilayer graphene at a magic twist angle. A propagating plasmon mode, which can be observed with optical nano-imaging, is associated with transitions between the moiré minibands.

Here, three-dimensional hafnium oxide and two-dimensional hexagonal boron nitride are integrated in the insulating section of double-layer graphene optical modulators, leading to a maximum bandwidth of 39 GHz and enhanced modulation efficiency.

In two-dimensional semiconductors excitons are strongly bound, suppressing the creation of free carriers. Here, the authors investigate the main exciton dissociation pathway in p-n junctions of monolayer WSe₂ by means of time and spectrally resolved photocurrent measurements.

Here, the authors realize fast, all-electrical modulation of the near-field interactions between a layer of erbium emitters and graphene, by in-situ tuning of the graphene Fermi energy. They obtain strong interactions with a  >1000-fold increased decay rate for about 25% of the erbium emitters, and electrically modulate these interactions with frequencies up to 300 kHz.

Experimental observation of intersubband transitions in van der Waals quantum wells is enabled by high spatial resolution imaging through near-field optical microscopy.

A significant challenge of infrared (IR) photodetectors is to funnel light into a small nanoscale active area and efficiently convert it into an electrical signal. Here, the authors couple a plasmonic antenna to hyperbolic phonon-polaritons in hexagonal-BN to highly concentrate mid-IR light into a graphene pn-junction.

Bright hot plasmon emission is observed in graphene due to the ultrafast relaxation of hot carriers that were excited by femtosecond laser pulses of visible light.

Interlayer transport can be made to occur slower or faster than intralayer scattering in van der Waals heterostructures, allowing the thermalization pathways for optically excited carriers to be tuned.

Propagating optical plasmons — collective electron excitations coupled to photons — are launched in graphene and studied with near-field optical microscopy, revealing ultra-strong optical field confinement and gate-tunable control of optical fields at nanoscale dimensions.

Thanks to the unique properties of twisted double bilayer graphene heterostructures, an ultra-broadband photoconductivity spanning the spectral range of 2–100 μm with internal quantum efficiencies of approximately 40% at speeds of 100 kHz is reported.

Phonon polaritons can be harnessed for SEIRA spectroscopy. Here, the authors demonstrate a compact on-chip phononic SEIRA platform based on a h-BN/graphene/h-BN heterostructure atop a metal split-gate that serves both as a SEIRA substrate and as a room-temperature infrared detector.

Excitation transfer between nitrogen–vacancy centres and graphene can be used to detect the spin of the electron in the nitrogen–vacancy centre through electrical measurements.

A device is presented that can detect mid-infrared plasmons in graphene encapsulated by hexagonal boron nitride via the thermoelectric effect; the natural decay product of the plasmons (electronic heat) is converted into a measurable voltage signal.

Phase velocity of graphene plasmons is electrically controlled in a set-up enabling tuning of the phase between 0 and 2π.

Time-domain interferometry and near-field scanning microscopy are used to investigate infrared phonon polaritons exhibiting hyperbolic dispersion. Negative phase velocity and group velocity as small as 0.002c are confirmed.

A single nitrogen-vacancy centre in a diamond nanocrystal can be trapped by optical tweezers and manipulated in all spatial directions.

Near-field photocurrent nanoscopy is used for imaging strongly confined terahertz graphene plasmons with linear dispersion.

Optical excitation of graphene can generate a photovoltage in less than 50 femtoseconds, and can result in efficient electron heating.

The relaxation processes of light-emitting excited ions are tunable, but electrical control is challenging. It is now shown that graphene can be used to manipulate the optical emission and relaxation of erbium near-infrared emitters electrically.

Free-electron Ramsey imaging enables space-, time- and phase-resolved electron imaging of weak optical near fields. Owing to its phase-resolving ability, this technique images chiral vortex–anti-vortex phase singularities of phonon-polariton modes in hexagonal boron nitride.

The authors develop a method to measure the coupling between a single photon source and any arbitrary photonic structure having constant density of electromagnetic states over the linewidth of the emitter. They demonstrate this method by an experiment on a single molecule coupled to an interrupted nanophotonic waveguide.

Knowledge of the quantum response of materials is essential for designing light–matter interactions at the nanoscale. Here, the authors report a theory for understanding the impact of metallic quantum response on acoustic graphene plasmons and how such response could be inferred from measurements.

Photodetectors based on graphene/WSe₂/graphene heterostructures combine an ultrafast photoresponse with high quantum efficiency.

Tuning the electronic interactions by changing the dielectric environment of twisted bilayer graphene reveals the disappearance of the insulating states and their replacement by superconducting phases, suggesting a competition between the two phases.