  In this work, we discuss the scattering features of a dipolar particle made
of large refractive index material by employing the concept of virtual gain and
virtual loss. The virtual gain and loss can be achieved in a lossless passive
nanostructure by shaping the temporal waveform of incident signals in the
complex frequency plane. We show that an appropriate tuning of excitation time
of the impinging field allows to capture and release the electromagnetic energy
on-demand for an arbitrary time scale in a lossless nanosphere. Thus, the
nanosphere obliges to emit monochromatic magnetic light which can be tuned
throughout the whole visible spectrum by varying the size of the nanosphere.
This proposal may find fruitful applications in lab-on-a-chip technologies and
the realization of monochromatic sectoral multipole light source with a large
quality factor at nanoscale level.
