A single-photon source is a key advancement for quantum computing, quantum sensing, metrology, and quantum communication. These applications use single photons and have demanding standards for the effectiveness of single-photon generation. All available single photon source (SPS) is probabilistic and the search for deterministic SPS is challenging and relatively new. In this work, we explore a quantitative approach that can be applied to various sources with well-defined mathematical distribution functions in photon emission. If we have a photon number distribution, then we can easily compute the possibility of emission of a single photon from the source. Here, we observe the single photon possibility in a quantum state named as New Generalised Binomial State. Furthermore, this criterion has been applied to a single photon added New Generalised Binomial state and a single photon subtracted New Generalised Binomial State too. This technique helps us to characterize the quality of a single photon source. We explore the variation of SPS probability with different parameters and it is found that probability varies with the total number of photons in a system, the q parameter should be negative and the addition of a Photon is more suitable than subtraction for single photon source criterion.
Quantum computation using photons offers one possible route towards the long-standing goal of scalable, fault-tolerant quantum computing. Within this realm, measurement-based quantum computing offers a promising approach exploiting many of the advantages of photons. Implementing photonic measurement-based architectures relies upon the deterministic generation of graph states composed of many entangled photons. Semiconductor quantum dots (QDs) are sources of indistinguishable single photons and hosts of solid-state spins, marking them desirable platforms for controlled entanglement generation. Such a platform consisting of a single charged QD coupled to a photonic cavity has been proven for the generation of multipartite spin-photon graph states. This dissertation will present advancements in the versatility and coherence of such entanglement generation. First, background on quantum dots, single photon generation, spin control, and entanglement will be introduced. Then, sources of error and decoherence will be addressed using control of the hole g-factor and dynamical decoupling techniques. The aim of versatility is advanced through results on the generation of four-partite graph states with on-demand reconfigurability of the type of state produced. Finally, a different paradigm using quantum dot molecules will be introduced, and novel estimation of important physical parameters in this system is developed.
Single photons from a solid state source are deterministically routed into different output modes by a fully integrated active optical switch network. Using a state-of-the-art single photon source made of a single quantum dot in a micropillar cavity and an innovative integrated optical demultiplexer, this scheme is capable of creating manifold single photon states. Such states are a crucial resource for photonic quantum information applications including linear optics quantum computation and quantum communications. (Picture: Mirko Lobino, Ph.D. et al., article number 1600297, in this issue)