Preparation Of Quantum Light Source Based On Photon Blockade

Non-classical light sources,such as single photon sources and entangled(correlated)photon pairs,are broadly applied in the fields of quantum cryptography,quantum information processing,quantum computation,quantum simulation,quantum imaging,and quantum precision measurement.A higher performance of quantum light sources is expected in the applications.It needs to have the properties of higher purity,higher brightness,higher collection efficiency,and compatible with the current photon integration technology.Up to now,the common experimental or theoretical methods to prepare quantum light source are N-V color center,quantum dot,spontaneous parametric down conversion,spontaneous four wave mixing,double excited cascade radiation and so on.The properties of single photon or photon pair prepared under these methods are imperfect.In order to prepare the quantum light source with better performance,persistent theoretical and experimental innovation are necessary and more effective preparation proposals are expected.In recent years,some researchers have proposed the implementation of photon blockade effect to prepare single photon source.Both conventional photon blockade caused by the strong nonlinear interaction between light and atom and unconventional photon blockade caused by the quantum interference have made some progress in theory and experiment.Up to now,the study of the photon blockade in the atom-cavity coupling system(J-C model)is based on the atom detuning equals to the cavity detuning.Theoretically,the physical mechanism of the photon blockade in J-C model remains open when the atom detuning is not equal to the cavity detuning.In addition,the study of the photon blockade is mainly focused on the field of monochromatic photon blocking.Theoretically,whether the photon blockade can be applied to the Bi-color photon blocking is an open interesting topic.Based on the discussion mentioned above,we comprehensive analysis the conventional and unconventional photon blockade mechanism of the J-C model and the two-mode parametrically driven cavity-atom system(U-C model)when relaxing the constraint condition(atom detuning equals to cavity detuning)to obtain a theoretical preparation scheme of single photon source with higher purity and brightness.We also study the model of a V type three-level atom in a two-mode cavity,explore the parameter conditions of two-color single photon blockade in the system,and then use it to construct two-color single photon source.Concretely,in this paper,we carried out the following work:1.We reexamine the physical mechanism of conventional and unconventional photon blockade of the J-C model via relaxing the traditional constraint condition.Firstly,we rely on the effective Hamiltonian under the interaction representation of J-C model,(a)study the physical mechanism of conventional photon blockade based on the dressed state of the system,(b)study the physical mechanism of unconventional photon blockade based on the quantum interference of system with bare states.Based on the theoretical analysis of the physical mechanism,we give a general parameter optimization condition for the stronger photon anti-bunching effect.Secondly,we theoretically analyze the expression of the second-order correlation function of the system,and we find that the system can obtain stronger anti-bunched photons when the atomic detuning is not equal to the cavity detuning than the case of the atomic detuning equal to the cavity detuning.Finally,we numerically evaluate the second-order correlation function of the system via the density matrix master equation of the system,and then compare the numerical results with the analytical results.2.We study the physical mechanism of conventional and unconventional photon blockade of the U-C model when relaxing the traditional constraint condition.Without considering the loss of the second harmonic mode,the U-C model is equivalent to the composite system of CQED system(J-C model)and parametric process,or it is equivalent to adding another two-level atom coupled with the fundamental mode to the nonlinear two-mode cavity model(cavity model)driven by the parametric/coherent two external fields.In this chapter,we use the same method used in the J-C model to study the physical mechanism of conventional and unconventional photon blockade in the U-C model,and give the optimal conditions of the strong photon antibunching in the strong coupling regime.Compared with the optimal conditions of J-C model and empty cavity model,we find that the optimal parameters for these three models are not independent.By numerically solving the density matrix master equation,we further present the second-order correlation function of the U-C model and analyze the photon statistical properties of the model.3.We study the possibility of the realization of bi-color single photon source under the conventional photon blockade.Firstly,based on the dressed states,we analyze the energy level transition of the system when?_s(28)?_e and(35)_a(28)(35)_b,and find that single photon blocking occurs for both two mode fields while strong anti-correlation between two-color photons.However,when?_s(28)-?_eand(35)_a(28)-(35)_b,we find that the two-mode fields behave single photon blocking while a strong cross correlation between them.Secondly,via the wave function method,we solve the steady-state Schrodinger equation,and then give the analytical expression of the second-order self/cross correlation function of the photons.We further discuss the photon statistical properties of the system under the above two parameter conditions.Finally,we numerically calculate the second-order auto/cross correlation function of the photons via the density matrix master equation,and then compare the results of numerical results with the analytical results.In summary,we systematically study the physical mechanism of photon blockade in three different models.We find that our proposed models are expected to be used to prepare the single photon source with higher purity.Additionally,it also can be provided a feasible theoretical scheme for the preparation of bi-color correlated photon pair source,and pave a way for the preparation of better quantum light source in experiment.