Figure 1. Energy diagram of the exciton energy shift due to OSE.

The diagram shows energy levels for the ground state, , and the two bright exciton states, , labelled by the azimuthal quantum number of the total angular momentum, m_j. The exciton transition energy is E₀. When a photon with energy E₀−Δ and with spin momentum σ+ interacts with the m_j=1 exciton, then an entangled state with energy E₀+δE forms (shaded box). The new state can be detected by a probe photon with the same spin, while the m_j=−1 exciton is left unperturbed.