Switchable Cavity Research Articles

Succulent-Inspired Implicit Structural Change for Smart "ON/OFF" Switchable and Flexible EMI Shielding Coating.

Modern miniaturized intelligent electronics call for smart switchable and flexible electromagnetic interference (EMI) shielding material for highly precise applications. However, most switchable EMI shielding materials are based on an explicit structural change. Herein, we report a succulent-inspired smart switchable MXene (WR-MXene) coating film realized by inner implicit structural change, which benefits from the insertion of our reversible large-cavity yolk-shell biomicrospheres. The novel switchable yolk-shell biomicrospheres contain a soft N-isopropylacrylamide (PNIPAM) hydrogel core, an "ON/OFF" switchable cavity (over 30% volume fraction), and a porous polydopamine (p-PDA) shell. The yolk-shell biomicrospheres can be obtained by a facile two-step polymerization and a simple drying-dehydration treatment. Because of the "ON/OFF" switchable void space brought by the smart biomicrospheres and conductive framework of MXene, an optimized ultralight and flexible WR-MXene coating film (vWR-coating film) showed both large switchable change (over 60 dB) and extraordinary EMI shielding effectiveness, reaching 95 and over 50 dB in the whole X band (8.2-12.4 GHz). These novel reversible yolk-shell biomicrospheres and the succulent-inspired switchable coating films are promising for smart flexible wearable devices and many advanced multifunctional systems needing dynamic real-time response.

Amplification of cascaded down-conversion by reusing photons with a switchable cavity

The ability to efficiently produce and manipulate nonclassical states of light is a critical requirement for the development of quantum optical technologies. In recent years, experiments have demonstrated that cascaded spontaneous parametric down-conversion is a promising approach to implement photon precertification, providing a way to overcome photon transmission losses for quantum communication, as well as to directly produce entangled three-photon states and heralded Bell pairs. However, the low efficiency of this process has so far limited its applicability beyond basic experiments. Here, we propose a scheme to amplify triplet production rates by using a fast switch and a delay loop to reuse photons that fail to convert on the first pass through the cascade's second nonlinear crystal. We construct a theoretical model to predict amplification rates and verify them in an experimental implementation. Our proof-of-concept device increases the rate of detected photon triplets as predicted, demonstrating that the method has the potential to dramatically improve the usefulness of cascaded down-conversion for device-independent quantum communication and entangled state generation.