Ghost resonance in the chaotic Chua's circuit.

We experimentally investigate the ghost resonance phenomenon in the electronic circuit of Chua operating in the chaotic regime. The circuit can be stimulated to jump between two single-scroll attractors by an external periodic signal with an amplitude above an intrinsic threshold. For subthreshold signals, jumps between the chaotic attractors can be promoted by a superposed white noise. We show that the circuit output can exhibit a well-defined ghost resonance signature, i.e., a resonance on a frequency that is absent in a multicomponent input signal, when the amplitudes of the input components are properly related. Further, we show that ghost resonance can be induced by the Chua's circuit's own chaotic dynamics when it is driven by a suprathreshold multicomponent signal without the need of an external noise source.