The Su-Schrieffer-Heeger (SSH) model has recently received considerable attention in condensed matter. Here, we investigate SSH-based charging protocols of quantum batteries (QBs) with $N$ spins. The hopping interaction induces ground state splitting, leading to different effects on the dimerization parameter to the QB in different quantum phase regimes. In the degenerate ground state regime, the dimerization parameter has little influence on the QB. In contrast, the dimerization parameter has a significantly quantum advantage in the fully nondegenerate ground state regime on energy and ergotropy. It also results in the dimerization spin pairs having larger occupations than other spins. Although the dimerization parameter can enhance the energy and ergotropy, the QB's capacity will decrease.

Quantum sensing with solid-state electron spin systems finds broad applications in diverse areas ranging from material and biomedical sciences to fundamental physics. Exploiting collective behavior of noninteracting spins holds the promise of pushing the detection limit to even lower levels, while to date, those levels are scarcely reached because of the broadened linewidth and inefficient readout of solid-state spin ensembles. Here, we experimentally demonstrate that such drawbacks can be overcome by a reborn maser technology at room temperature in the solid state. Owing to maser action, we observe a fourfold reduction in the electron paramagnetic resonance linewidth of an inhomogeneously broadened molecular spin ensemble, which is narrower than the same measured from single spins at cryogenic temperatures. The maser-based readout applied to near zero-field magnetometry showcases the measurement signal-to-noise ratio of 133 for single shots. This technique would be an important addition to the toolbox for boosting the sensitivity of solid-state ensemble spin sensors.

By using femtosecond pump-probe spectroscopy with broadband detection from near-infrared to midinfrared, the carrier and phonon dynamics in few-layer 2H–MoTe₂ after ultrafast excitation have been investigated in detail. Immediately following the photoexcitation, an ultrafast relaxation of the generated hot carriers by releasing phonons is observed within hundreds of femtoseconds. The subsequent electron-hole recombination with a time constant of ∼1.5 ps is clearly identified and demonstrated to be mediated through a defect-assisted process. Furthermore, we confirm that the observed redshift of the exciton resonance energy on longer time scales arises from the ultrafast thermalization of the 2H–MoTe₂ lattice caused by the transfer of electronic excitation to the phonon system. As a result, the thermalization dynamics of the lattice within 2 ps and the following cooling process of the phonon system on the 100 ps time scale are directly monitored.

Femtosecond transient absorption measurements have been performed to study the pump wavelength- and fluence-dependent hot carrier relaxation dynamics in monolayer MoS ₂ . The relaxation process of the photoinduced carriers monitored within hundreds of femtoseconds after photoexcitation is demonstrated to be achieved through the carrier–phonon scattering mechanism. It is observed that an efficient hot-phonon effect can slow down the relaxation rate by around three times with the injected carrier density changing from 1 × 10 ¹² to 3 × 10 ¹³ cm ⁻² . A pronounced increase in the hot carrier relaxation time with decreasing temperature is further detected, which is attributed to the decreased phonon occupancy at lower temperature.