Authors
Zubizarreta Casalengua, EduardoAdvisors
Laussy, FabriceAffiliation
Faculty of Science and EngineeringIssue Date
2022-11
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The characterisation of the quantum states of light and their subsequent realisation is thought to be an indispensable step to bring in quantum technologies to the real world. The emergence of quantum cryptography, quantum security protocols or quantum computers, among others, demand implicitly or explicitly trustworthy tools and components to carry through the research in its first stages. A deterministic or on-demand single-photon source and, more recently, an N-photon emitter, seem to play a crucial role. Nevertheless, even the correct characterisation of the former is still a source of discussion and there exist several criteria to do so. The identification of the latter is, as expected, a challenging task. With the emergence of multiphoton physics, the horizon of quantum light sources is wider. The tools to identify and classify multiphoton emission are still in development. We present the methods to study the dynamics and correlations of some candidate systems that have been proposed, focusing on the analytical solutions through perturbative methods, valid, for instance, for weakly driven or weakly coupled systems. In particular, the frequency-resolved correlations can be exactly obtained in this way. We also consider the effect of detection on the correlations. The noisy apparatus and their finite time resolution can modify the photon statistics. Some photons may be left undetected or misplaced (in time), additional counts may be recorded as well. We revisit the photon counting formula, that was popular in the birth of Quantum Optics, to obtain the counting probabilities in continuously driven (CW) systems and we focus then on the spontaneous emission of N photons. We observe, for probability distributions of CW systems, a clear deviation from Poissonian statistics in both the short and long time regimes. We find how such a behaviour is inherited from the photon correlations. A good starting point to study the bundler—the N-photon emitter—is the spontaneous emission of N photons. The counting probabilities are computed without and with spectral filtering, making emphasis on how the kind of filter affects the detection. Then, the full structure of the bundle is completely captured by the probability functions of the emission time of the individual photons. The results are ultimately compared with the actual bundler, showing qualitative and quantitative agreement. A brief introduction is given to spatial correlation induced by the ensemble statistics. Some clarifying examples reveal how the statistics are manifested depending on the kind of states. On the other hand, a dynamical model introducing a space dependent sensor method is provided for the scattering and how the spatial distribution is modified by the time resolution limitation. Interestingly, the wave packet before and after the scattering get effectively admixed and interfere with itself displaying characteristic fringes. The main objective of this Thesis is to make an exhaustive characterisation of multiphoton emission, starting with the usual treatment in terms of the luminescence spectrum and the second-order photon correlation function g(2), considering mechanisms that can take place in the detection process such as spectral filtering or contamination of the signal due to time jitter and noise. We develop tools to facilitate and speed up the computation of these quantities, either analytically or numerically, within the range of validity of the Born–Markov approximation and highlighting situations in which perturbation theory is applicable. Finally, we go beyond and take into account other statistical quantities such as the waiting time distribution or higher order correlators and eventually compute counting statistics, which results in a good and promising procedure to characterise and subsequently classify multiphoton emission.Citation
Zubizarreta Casalengua, E. (2022) Multiphoton correlations and emitters. University of Wolverhampton. http://hdl.handle.net/2436/625173Publisher
University of WolverhamptonType
Thesis or dissertationLanguage
enDescription
A thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of Philosophy.Collections
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