Dissipative dynamics of spins in quantum dots

We present a theory for the dissipation of electronic spins trapped in quantum dots due to their coupling to the host lattice acoustic phonon modes. Based on the theory of dissipative two level systems for the spin dynamics, we derive a relation between the spin dissipative bath, the electron confinement, and the electron-phonon interaction. We find that there is an energy scale, typically smaller than the electronic lateral confinement energy, which sets the boundary between different dissipative regimes .Comment: 4 pages, 2 eps figure

Dissipative dynamics of a two - level system resonantly coupled to a harmonic mode

We propose an approximation scheme to describe the dynamics of the spin-boson model when the spectral density of the environment shows a peak at a characteristic frequency $\Omega$ which can be very close (or even equal) to the spin Zeeman frequency $\Delta$. Mapping the problem onto a two-state system (TSS) coupled to a harmonic oscillator (HO) with frequency $\omega_0$ we show that the representation of displaced HO states provides an appropriate basis to truncate the Hilbert space of the TSS-HO system and therefore a better picture of the system dynamics. We derive an effective Hamiltonian for the TSS-HO system, and show it furnishes a very good approximation for the system dynamics even when its two subsystems are moderately coupled. Finally, assuming the regime of weak HO-bath coupling and low temperatures, we are able to analytically evaluate the dissipative TSS dynamics.Comment: 12 pages, 2 figures; V2: Published versio