Entanglement from Quantum Dots

Many different systems and processes are capable of delivering single photons. Among them we can name single atoms and ions, nitrogen-vacancy centers, devices based on spontaneous parametric downconversion and quantum dots. Nevertheless, it is the entanglement of photons that keeps us searching for new systems and improving the existing ones. Photon- entanglement generation from quantum dots promises a very versatile system, which joins semiconductor and quantum. In other words, it is a system which embodies the properties of a single atom to be a well controllable few-level system as well as the potential for integration and commercialization characteristic for semiconductor devices. We propose several experimental ideas and approaches with an intention to expand the range of quantum states of light emitted by quantum dots. In particular, we propose methods for creating and improving time-bin as well as polarization entanglement from a quantum dot. Also, we would like to join these two entangling procedures and generate hyper-entangled photon pairs. Additionally, we propose to realize a scheme to generate multiphoton entangled states. Long distance quantum communications, linear optical quantum computing, and secure quantum communications use photons entangled is some degree of freedom where the choice of the type of entanglement strongly depends on the application. Our goal is to bring quantum dots closer to serve each of these purposes. The ability to generate photons entangled in various degrees of freedom, as well as generation of hyper-entanglement enriches quantum dot systems and brings them to the same level with other more mature sources like, for example, parametric downconversion. We believe that the ideas presented in this proposal have a very strong basis and that their implementation will push further the current limits of the field.