Symmetry-breaking instabilities in symmetric coupled-quantum-dot structures

The effect of the Coulomb charging energy on the time evolution of the electron occupation probability in a coupled-dot system is numerically investigated by use of nonlinear coupled equations derived from the Schrödinger equation. For the initial condition that the electron occupation probability is equally distributed to two quantum dots, a small initial fluctuation in the distribution of the electron occupation probability causes the symmetry-breaking instabilities of the distribution for Coulomb charging energies larger than a certain threshold value. The numerical analyses with various initial conditions are also discussed.