  Integration of devices generating nonclassical states~(such as entanglement)
into photonic circuits is one of the major goals in achieving integrated
quantum circuits~(IQCs). This is demonstrated successfully in recent decades.
Controlling the nonclassicality generation in these micron-scale devices is
also crucial for the robust operation of the IQCs. Here, we propose a
micron-scale quantum entanglement device whose nonlinearity (so the generated
nonclassicality) can be tuned by several orders of magnitude via an
\textit{applied voltage} without altering the linear response. Quantum
emitters~(QEs), whose level-spacing can be tuned by voltage, are embedded into
the hotspot of a metal nanostructure~(MNS). QE-MNS coupling introduces a Fano
resonance in the ``nonlinear response''. Nonlinearity, already enhanced
extremely due to localization, can be controlled by the QEs' level-spacing.
Nonlinearity can either be suppressed (also when the probe is on the device) or
be further enhanced by several orders. Fano resonance takes place in a
relatively narrow frequency window so that $\sim$meV voltage-tunability for QEs
becomes sufficient for a \textit{continuous} turning on/off of the
nonclassicality. This provides as much as 5 orders of magnitude modulation
depths.
