Coherent quantum switch driven by optimized laser pulses

We present two models of coherent quantum switches constructed from a single-electron quantum ring and a double quantum dot, respectively. The systems are driven by picosecond laser pulses obtained using quantum optimal control theory. The optimized pulses generate electron-current flips in the ring (magnetic switch) and electron transport in the double dot (charge switch) in significantly shorter times and higher accuracies than previously used finite-length continuous waves. This opens applicable paths into coherent single-qubit gates operated by terahertz lasers.