Photon-echo quantum beats in a magnetic field

Photon echoes retrieved from semiconductor spins: access to basis for long-term optical memories

“…-in contrast to other elements -contain the phase factor exp(±iω 0 τ 12 ), see Eqs. (14). For distinctness, the nondiagonal elements, which are proportional to exp(−iω 0 τ 12 ), are given by:…”

“…Already at the early stage of photon echo experiments the spin level structure of ground and excited states was recognized to contribute to the formation of spontaneous and stimulated photon echo signals [11,12,13]. If optically addressed states possess orbital and/or spin angular momenta then the splitting of these states by a magnetic field (the Zeeman effect) provides an additional degree of freedom for the control of photon echo through optical selection rules [14,15,16]. Moreover, transfer of coherence from optical to spin excitations has been suggested to considerably extend the storage times as demonstrated for quasi-atomic systems having optical and spin coherences with comparable lifetimes [17].…”