Abstract

Due to unique and controllable properties and the availability of fast optical control methods, quantum dots are considered as promising candidates for the use as qubits. It is advantageous to store the logical values in spin states of an electron in a quantum dot (due to the long decoherence time) and perform the operations using optical coupling to the charge degrees of freedom (short switching time). The electromagnetic field of an optical wave does not couple directly to the spin degrees of freedom but it is possible to induce charge dynamics dependent on the spin state of the electron and thus to perform unitary operations on the spin. The theoretical proposal [1] is based on off-resonant coupling to a charged exciton (trion) state. As the quantum dots are embedded in a solid state matrix, the confined carriers interact with phonons leading to a loss of coherence. Since the spin rotation in this approach results from charge dynamics, it is subject to dephasing due to the phonon response to the evolving charge density.

© 2007 IEEE