Current Detection of Superradiance and Induced Entanglement of Double Quantum Dot Excitons

We propose to measure the superradiance effect by observing the current through a semiconductor double-dot system. An electron and a hole are injected separately into one of the quantum dots to form an exciton and then recombine radiatively. We find that the stationary current shows oscillatory behavior as one varies the interdot distance. The amplitude of oscillation can be increased by incorporating the system into a microcavity. Furthermore, the current is suppressed if the dot distance is small compared to the wavelength of the emitted photon. This photon trapping phenomenon generates the entangled state and may be used to control the emission of single photons at predetermined times.

Figure 1

Proposed device structure. Two InAs quantum dots are embedded in a $p\mathrm{\text{−}}i\mathrm{\text{−}}n$ junction. Above dot 2 is a metal gate, which controls the energy gap and orientation of the dipole.

Figure 2

Stationary tunnel current, Eq. (4), as a function of dot distance $d$. The interference effect is seen clearly (inset) by incorporating the system inside a rectangular microcavity. The vertical and horizontal units are 100 pA and ${\lambda }_0$, respectively.

Figure 3

Occupation probability of the entangled states $n_S$ (solid line) and $n_T$ (dashed line). The inset shows the results inside a rectangular microcavity.