Using quantum state protection via dissipation in a quantum-dot molecule to solve the Deutsch problem

The wide set of control parameters and reduced size scale make semiconductor quantum dots attractive candidates to implement solid-state quantum computation. Considering an asymmetric double quantum dot coupled by tunneling, we combine the action of a laser field and the spontaneous emission of the excitonic state to protect an arbitrary superposition state of the indirect exciton and ground state. As a by-product we show how to use the protected state to solve the Deutsch problem.

Figure 1

Time evolution of the population of the states $|0\rangle$ (black solid line), $|1\rangle$ (red dashed line), and $|2\rangle$ (blue dotted line) considering the application of a laser field with amplitude $\overline{\Omega }=\Omega (\sqrt{2}+1)$, relative phase $\overline{\varphi }=0$, and frequency $\overline{\omega }={\omega }_L$. The initial state of the system is $|E_0(\pi /2,\varphi )\rangle$ for (a) $\varphi =0$ and (b) $\pi$. The physical parameters are $\Omega =T_e=200$ $\mu$eV, ${\Gamma }_1=3$ $\mu$eV, and ${\Gamma }_2={10}^{-4}{\Gamma }_1$.