Electron number dependence of spin triplet–singlet relaxation time

In a GaAs single quantum dot, the relaxation time T1 between spin triplet and singlet states has been measured for the last few even electron numbers. The singlet–triplet energy separation EST is tuned as a control parameter for the comparison of T1 between different electron numbers. T1 steadily decreases with increasing electron numbers from 2-electrons to 6-electrons. This implies an enhancement of the spin–orbit coupling strength due to multi-electron interaction in a quantum dot.