  Presence of coherent resonant tunneling in quantum dot (zero-dimensional) -
quantum well (two-dimensional) heterostructure is necessary to explain the
collective oscillations of average electrical polarization of excitonic dipoles
over a macroscopically large area. This was measured using photo excited
capacitance as a function of applied voltage bias. Resonant tunneling in this
heterostructure definitely requires momentum space narrowing of charge carriers
inside the quantum well and that of associated indirect excitons, which
indicates bias dependent itinerant Bose-Einstein condensation of excitons.
Observation of periodic variations in negative quantum capacitance points to
in-plane coulomb correlations mediated by long range spatial ordering of
indirect, dipolar excitons. Enhanced contrast of quantum interference beats of
excitonic polarization waves even under white light and observed Rabi
oscillations over a macroscopically large area also support the presence of
density driven excitonic condensation having long range order. Periodic
presence (absence) of splitting of excitonic peaks in photocapacitance spectra
even demonstrate collective coupling (decoupling) between energy levels of the
quantum well and quantum dots with applied biases, which can potentially be
used for quantum gate operations. All these observations point to experimental
control of macroscopically large, quantum state of a two-component
Bose-Einstein condensate of excitons in this quantum dot - quantum well
heterostructure. Therefore, in principle, millions of two-level excitonic
qubits can be intertwined to fabricate large quantum registers using such
hybrid heterostructure by controlling the local electric fields and also by
varying photoexcitation intensities of overlapping light spots.
