Nature nanotechnology最新文献

The ultimate limit for laser miniaturization would be achieving lasing action in the lowest-order cavity mode within a device volume of ≤(λ/2n)³, where λ is the free-space wavelength and n is the refractive index. Here we highlight the equivalence of localized surface plasmons and surface plasmon polaritons within resonant systems, introducing nanolasers that oscillate in the lowest-order localized surface plasmon or, equivalently, half-cycle surface plasmon polariton. These diffraction-limited single-mode emitters, ranging in size from 170 to 280 nm, harness strong coupling between gold and In_xGa_1−xAs_1−yP_y in the near-infrared (λ = 1,000–1,460 nm), away from the surface plasmon frequency. This configuration supports only the lowest-order dipolar mode within the semiconductor’s broad gain bandwidth. A quasi-continuous-level semiconductor laser model explains the lasing dynamics under optical pumping. In addition, we fabricate isolated gold-coated semiconductor discs and demonstrate higher-order lasing within live biological cells. These plasmonic nanolasers hold promise for multi-colour imaging and optical barcoding in cellular applications.

The pervasive model for a solvated, ion-filled nanopore is often a resistor in parallel with a capacitor. For conical nanopore geometries, here we propose the inclusion of a Warburg-like element, which is necessary to explain otherwise anomalous observations such as negative capacitance and low-pass filtering of translocation events (we term this phenomenon as Warburg filtering). The negative capacitance observed here has long equilibration times and memory (that is, mem-capacitance) at negative voltages. We used the transient occlusion of the pore using λ-DNA and 10 kbp DNA to test whether events are being attenuated by purely ionic phenomena when there is sufficient amplifier bandwidth. We argue here that both phenomena can be explained by the inclusion of the Warburg-like element, which is mechanistically linked to concentration polarization and activation energy to generate and maintain localized concentration gradients. We conclude the study with insights into the transduction of molecular translocations into electrical signals, which is not simply based on pulse-like resistance changes but instead on the complex and nonlinear storage of ions that enter dis-equilibrium during molecular transit.

The world of nanoscales in fluidics is the frontier where the continuum of fluid mechanics meets the atomic, and even quantum, nature of matter. While water dynamics remains largely classical under extreme confinement, several experiments have recently reported coupling between water transport and the electronic degrees of freedom of the confining materials. This avenue prompts us to reconsider nanoscale hydrodynamic flows under the perspective of interacting excitations, akin to condensed matter frameworks. Here we show, using a combination of many-body theory and molecular simulations, that the flow of a liquid can induce the flow of another liquid behind a separating wall, at odds with the prediction of continuum hydrodynamics. We further show that the range of this ‘flow tunnelling’ can be tuned through the solid’s electronic excitations, with a maximum occurring when these are at resonance with the liquid’s charge density fluctuations. Flow tunnelling is expected to play a role in global transport across nanoscale fluidic networks, such as lamellar graphene oxide or MXene membranes. It further suggests exploiting the electronic properties of the confining walls for manipulating liquids via their dielectric spectra, beyond the nature and characteristics of individual molecules.

Colloidal quantum dots (CQDs) are promising for infrared photodetectors with high detectivity and low-cost production. Although CQDs enable photoinduced charge multiplication, thermal noise in low-bandgap materials limits their performance in IR detectors. Here we present a pioneering architecture of a CQD-based infrared photodetector that uses kinetically pumped avalanche multiplication. By applying a strong electric field to a thick CQD layer (>540 nm), electrons acquire kinetic energy beyond the bandgap of the CQD material, initiating kinetically pumped charge multiplication. Optimizing the dot-to-dot distance to approximately 4.1 nm improves performance by balancing impact ionization and electron hopping. Our optimized CQD-based infrared photodetector achieved a maximum multiplication gain of 85 and a peak detectivity of 1.4 × 10¹⁴ Jones at 940 nm. This architecture offers potential for single-photon detection and ultrahigh detectivity applications.