Different Types of Photon Entanglement from a Constantly Driven Quantum Emitter Inside a Cavity. Issue 1 (14th December 2020) - Seidelmann, Tim
Abstract: Bell states are the most prominent maximally entangled photon states. In a typical four‐level emitter, like a semiconductor quantum dot, the photon states exhibit only one type of Bell state entanglement. By adding an external driving to the emitter system, also other types of Bell state entanglement are reachable without changing the polarization basis. In this work, it is shown under which conditions the different types of entanglement occur and analytical equations are given to explain these findings. Furthermore, special points are identified, where the concurrence, being a measure for the degree of entanglement, drops to zero, while the coherences between the two‐photon states stay strong. Results of this work pave the way to achieve a controlled manipulation of the entanglement type in practical devices. Abstract : Entangled photon states are at the heart of quantum physics, most prominent being the maximally entangled Bell states. Analyzing a driven four‐level emitter–cavity system, it is demonstrated that two different types of entanglement and special points with vanishing concurrence emerge, depending on the resonance and excitation conditions. All results are well explained using analytic expressions.