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Squeezed light has long been used to enhance the precision of a single optomechanical sensor. An emerging set of proposals seeks to use arrays of optomechanical sensors to detect weak distributed forces, for applications ranging from gravity-based subterranean imaging to dark matter searches; however, a detailed investigation into the quantum-enhancement of this approach remains outstanding. Here, we propose an array of entanglement-enhanced optomechanical sensors to improve the broadband sensitivity of distributed force sensing. By coherently operating the optomechanical sensor array and distributing squeezing to entangle the optical fields, the array of sensors has a scaling advantage over independent sensors (i.e.,$$\sqrt{M}\to M$$$\sqrt{M}\to M$, whereMis the number of sensors) due to coherence as well as joint noise suppression due to multi-partite entanglement. As an illustration, we consider entanglement-enhancement of an optomechanical accelerometer array to search for dark matter, and elucidate the challenge of realizing a quantum advantage in this context.

Band convergence is considered a clear benefit to thermoelectric performance because it increases the charge carrier concentration for a given Fermi level, which typically enhances charge conductivity while preserving the Seebeck coefficient. However, this advantage hinges on the assumption that interband scattering of carriers is weak or insignificant. With first-principles treatment of electron-phonon scattering in the CaMg₂Sb₂-CaZn₂Sb₂Zintl system and full Heusler Sr₂SbAu, we demonstrate that the benefit of band convergence can be intrinsically negated by interband scattering depending on the manner in which bands converge. In the Zintl alloy, band convergence does not improve weighted mobility or the density-of-states effective mass. We trace the underlying reason to the fact that the bands converge at a one k-point, which induces strong interband scattering of both the deformation-potential and the polar-optical kinds. The case contrasts with band convergence at distant k-points (as in the full Heusler), which better preserves the single-band scattering behavior thereby successfully leading to improved performance. Therefore, we suggest that band convergence as thermoelectric design principle is best suited to cases in which it occurs at distant k-points.

Moving contact-lines (CLs) dissipate. Sessile droplets, mechanically driven into resonance by plane-normal forcing of the contacting substrate, can exhibit oscillatory CL motions with CL losses dominating bulk dissipation. Conventional practice measures CL dissipation based on the rate of mechanical work of the unbalanced Young’s force at the CL. Typical approaches require measurements local to the CL and assumptions about the “equilibrium” contact angle (CA). This paper demonstrates how to use scanning of forcing frequency to characterize CL dissipation without any dependence on measurements from the vicinity of the CL. The results are of immediate relevance to an International Space Station (ISS) experiment and of longer-term relevance to Earth-based wettability applications. Experiments reported here use various concentrations of a water-glycerol mixture on a low-hysteresis non-wetting substrate.

Thermoelectric (TE) generators enable the direct and reversible conversion between heat and electricity, providing applications in both refrigeration and power generation. In the last decade, several TE materials with relatively high figures of merit (zT) have been reported in the low‐ and high‐temperature regimes. However, there is an urgent demand for high‐performance TE materials working in the mid‐temperature range (400–700 K). Herein, p‐type AgSbTe₂materials stabilized with S and Se co‐doping are demonstrated to exhibit an outstanding maximum figure of merit (zT_max) of 2.3 at 673 K and an average figure of merit (zT_ave) of 1.59 over the wide temperature range of 300–673 K. This exceptional performance arises from an enhanced carrier density resulting from a higher concentration of silver vacancies, a vastly improved Seebeck coefficient enabled by the flattening of the valence band maximum and the inhibited formation of n‐type Ag₂Te, and ahighly improved stability beyond 673 K. The optimized material is used to fabricate a single‐leg device with efficiencies up to 13.3% and a unicouple TE device reaching energy conversion efficiencies up to 12.3% at a temperature difference of 370 K. These results highlight an effective strategy to engineer high‐performance TE material in the mid‐temperature range.