EDITORS' SUGGESTION
Near-field heat transfer is essential in thermal nanolithography, scanning thermal microscopy, and thermophotovoltaics, for example, but applications are hindered by low heat-current amplitude. This work shows that the heat current can be significantly boosted in the presence of localized zero-energy edge states, which offers a means of thermal switching via externally tuning for the presence or absence of such states. Surprisingly, heat transfer exhibits nonmonotonic behavior with respect to gap distance, at these length scales; it does not simply increase as the gap closes. These insights could change the way we approach thermal management at the nanoscale.
Gaomin Tang, Han Hoe Yap, Jie Ren, and Jian-Sheng Wang
Phys. Rev. Applied 11, 031004 (2019)
LETTER
Nanoscale microwave generators based on magnetization precession require a narrow and tunable spectral band, high absolute amplitude, and high-frequency tunability—a challenging combination. The authors show that this combination can be achieved under ultrafast optical excitation of a nanolayer of galfenol, a ferromagnetic alloy of iron and gallium. In a film several nanometers thick, a femtosecond laser pulse excites only the ground spin-wave mode, not the higher-order modes that would broaden the precession spectral band. The extremely narrow spectral response remains easily detectable above 100 GHz, which is a boon for applications in nanomagnetism and spintronics.
A.V. Scherbakov et al.
Phys. Rev. Applied 11, 031003 (2019)
EDITORS' SUGGESTION
Terahertz accelerators can achieve potential gradients beyond 200 MV/m. Gyrotrons are the only power sources capable of producing megawatt-level, microsecond-long pulses in this frequency range, yet nanosecond-long pulses are required for breakdown-free operation. The authors explore the possibility of using a single GaAs wafer to enable production of the required pulse widths, with rise and fall times that closely track the illuminating laser’s pulse length. They demonstrate and quantify the reflective properties and laser-induced photoconductive effect of GaAs in the millimeter-wave regime, for use in a laser-operated shutter.
S.V. Kutsaev et al.
Phys. Rev. Applied 11, 034052 (2019)
EDITORS' SUGGESTION
Wavelengths in the telecommunication window (ca.1.25–1.65 m) are ideal for quantum communication, due to the low transmission loss in optical-fiber networks. To realize quantum networks operating at these wavelengths, we need long-lived quantum memories that couple efficiently to telecom-band photons. This study proposes using optical tweezers to couple neutral ytterbium atoms, which have a strong telecom-wavelength transition, to a silicon photonic-crystal cavity. The combination of high system efficiency, telecom-band operation, and long coherence times makes this platform well suited for quantum optics on a silicon chip and long-distance quantum communication.
Jacob P. Covey et al.
Phys. Rev. Applied 11, 034044 (2019)
