  Recent advances in non-radiative wireless power transfer (WPT) technique
essentially relying on magnetic resonance and near-field coupling have
successfully enabled a wide range of applications. However, WPT systems based
on double resonators are severely limited to short- or mid-range distance, due
to the deteriorating efficiency and power with long transfer distance. WPT
systems based on multi-relay resonators can overcome this problem, which,
however, suffer from sensitivity to perturbations and fabrication
imperfections. Here, we experimentally demonstrate a concept of topological
wireless power transfer (TWPT), where energy is transferred efficiently via the
near-field coupling between two topological edge states localized at the ends
of a one-dimensional radiowave topological insulator. Such a TWPT system can be
modelled as a parity-time-symmetric Su-Schrieffer-Heeger (SSH) chain with
complex boundary potentials. Besides, the coil configurations are judiciously
designed, which significantly suppress the unwanted cross-couplings between
nonadjacent coils that could break the chiral symmetry of the SSH chain. By
tuning the inter- and intra-cell coupling strengths, we theoretically and
experimentally demonstrate high energy transfer efficiency near the exceptional
point of the topological edge states, even in the presence of disorder. The
combination of topological metamaterials, non-Hermitian physics, and WPT
techniques could promise a variety of robust, efficient WPT applications over
long distances in electronics, transportation, and industry.
