Deterministic Generation of Polarization Entangled single Photons Cluster States

ended

Measurement based quantum computing is one of the most fault-tolerant architectures proposed for quantum information processing. It opens the possibility of performing quantum computing tasks using linear optical systems. An efficient route for measurement based quantum computing utilizes highly entangled states of photons, called cluster states. Propagation and processing quantum information is made possible this way using only single qubit measurements. It is highly resilient to qubit losses. In addition, single qubit measurements of polarization qubits is easily performed with high fidelity using standard optical tools. These features make photonic clusters excellent platforms for quantum information processing. Constructing photonic cluster states, however, is a formidable challenge, attracting vast amounts of research efforts. While in principle it is possible to build up cluster states using interferometry, such a method is of a probabilistic nature and entails a large overhead of resources. The use of entangled photon pairs reduces this overhead by a small factor only. We outline a novel route for constructing a deterministic source of photonic cluster states using a device based on semiconductor quantum dot. Our proposal follows a suggestion by Lindner and Rudolph. We use repeated optical excitations of a long lived coherent spin confined in a single semiconductor quantum dot and demonstrate for the first time practical realization of their proposal. Our preliminary demonstration presents a breakthrough in quantum technology since deterministic source of photonic cluster, reduces the resources needed quantum information processing. It may have revolutionary prospects for technological applications as well as to our fundamental understanding of quantum systems. We propose to capitalize on this recent breakthrough and concentrate on R&D which will further advance this forefront field of science and technology by utilizing the horizons that it opens.