Abstract It is important to generate stable nonclassical correlation and wide‐band quantum field in quantum optical communication. In this paper, a scheme is proposed to manipulate the nonclassical intensity correlation of two output fields by a coherent coupling laser and an incoherent pumping field. The core of the scheme is that the coherent field is applied to manipulate the intracavity polaritons, and the incoherent pumping field is used to control the linear absorption and the atomic coherence. With the incoherent field, atoms are repopulated on the excited state . It induces a wide‐band zero absorption of a probe field and the negative dispersion that can be used to realize a white‐light cavity. In addition, with the increasement of the incoherent pumping rate, the wide‐band maximum stable intensity correlation and the nonclassical field with sub‐Poissonian distribution are attained, which is verified by the evolution of the second‐order correlation of two output channels.
Abstract It is important to generate stable nonclassical correlation and wide‐band quantum field in quantum optical communication. In this paper, a scheme is proposed to manipulate the nonclassical intensity correlation of two output fields by a coherent coupling laser and an incoherent pumping field. The core of the scheme is that the coherent field is applied to manipulate the intracavity polaritons, and the incoherent pumping field is used to control the linear absorption and the atomic coherence. With the incoherent field, atoms are repopulated on the excited state . It induces a wide‐band zero absorption of a probe field and the negative dispersion that can be used to realize a white‐light cavity. In addition, with the increasement of the incoherent pumping rate, the wide‐band maximum stable intensity correlation and the nonclassical field with sub‐Poissonian distribution are attained, which is verified by the evolution of the second‐order correlation of two output channels.
Abstract We propose a scheme for the generation of a white-light cavity with multiple broad frequency bands by using an incoherent pumped multi-level atomic system. Owing to the destructive quantum interference induced by the coherent coupling fields, multiple negative dispersion regions with a broadband characteristic can be achieved within the transparency windows, which result from resonant gain suppression. By simply adjusting the control fields, the negative material dispersion compensates the normal dispersion of cavity in the transparency regions, so we can obtain a white-light cavity with multiple wide frequency bands. Moreover, the cavity linewidth depends explicitly on the incoherent pumping rate and gas density. When the system interacts with more coherent coupling fields, we anticipate that more bands will be generated in the cavity transmission spectrum. The proposed scheme can find applications in many fields, such as a wide-band optical switch for multiple signals.
Abstract We demonstrate theoretically the feasibility of correlated entangled photon-pair generation with vanishing threshold in a bimodal cavity setup that uses a single V-type three level atom pumped by dual incoherent sources and driven by two coherent fields. The photon-pair is shown to be entangled only for low levels of the incoherent pumps and owes its origin solely to the coherent drives. Our results show that the dual incoherent pumping with no coherent drive can lead to amplification of the cavity fields with strong inter-mode antibunching but no entanglement. We analyse our results in terms of an interplay between coherent and incoherent processes involving cavity-dressed states. Both the inter- and intra-mode Hanbury–Brown–Twiss (HBT) functions exhibit temporal oscillations in the strong-coupling cavity QED regime. Our theoretical scheme for the generation of nonclassical and entangled photon pairs may find interesting applications in quantum metrology and quantum information science.
We consider ultracold atoms in a far detuned optical lattice across a high-Q optical resonator. Applying an external driving laser to the atoms red detuned from the cavity mode by one vibrational quantum induces cavity-enhanced sideband cooling. For a dense and cold enough atomic ensemble we predict an oscillation threshold for optical Raman sideband lasing concurrent with coherent matter-wave amplification. Above threshold, photons and atoms in the lowest band are dominantly created pairwise via stimulated emission with a strong suppression of competing spontaneous processes. In close analogy to a nondegenerate parametric oscillator, we find sub-Poissonian photon statistics and almost perfect nonclassical atom-photon number correlations. Injecting atoms in higher vibrational bands via tunneling or incoherent scattering then leads to continuous, simultaneous generation of a coherent atom beam and laser light with nonclassical atom-field correlations.
Cavity quantum electrodynamics is the intersection of quantum physics and microcavity optics research. In this paper, we presented a two-mode cavity coupled to a classical field driven by N three-level atoms to prepare entangled coherent states based on cavity QED. In this scheme, we adopt the interaction between the three-level atoms and the two-mode optical cavity, The initial state of one optical field is an odd-even coherent state, while the initial state of another optical field is a coherent state. After considering the time evolution of the initial states with the system, we obtained the specific form of the time evolution of the quantum states and prepared the entangled coherent state successfully. We discussed and analysed some of the nonclassical properties of the optical field and quantum states, including the second-order correlation function and the Wigner function. The results show that when calculating the second-order correlation function, the photons are found to exhibit a sub-Poisson distribution at some points in time. In addition, when observing the Wigner function of the quantum states evolving with time, it is found that there is a negative part of the Wigner distribution at some moments, which implies that the quantum state exhibits nonclassical properties at these certain moments.
In this paper, we investigate the effects of incoherent pumping on quantum correlations in a Λ -type atomic system driven by coherent and incoherent fields simultaneously. With the adiabatic elimination treatment, we show that the stable “one-way” Einstein–Podolsky–Rosen (EPR) steering is generated without the requirement of good cavity limitation. More interestingly, the asymmetrical EPR steering is simply controlled by the polarized angle of the incoherent field. The internal mechanisms can be understood based on dressed-state representation, in which the population differences are strongly modified by the quantum interference from incoherent pumping. The phase-sensitive quantum correlations in the present scheme may find potential applications in quantum information processing.
We propose a possibility to study the quantum light excitation of atomic systems. To confine our study, we limit the configuration to two and four level emitters as target systems. Source and target are coupled via unidirectional waveguide. We numerically implement the cascaded formalism and use the source-target approach. Herein, we focus on continuous excitation scenarios where the source system is excited by continuous incoherent or coherent pumping. We demonstrate that, to a certain extent, one can control the target system's photon statistics via the source system pumping mechanism. Additionally, different coupling regimes in both cavities can change the output of the target system. In addition, we show that via tuning the cavity’s parameters one can produce an exotic type of quasi-probability distributions, a flat Fock state distributions. We also discuss the different obtained photon statistics for different coupling regimes. The used quantum light source, driven by spontaneous emission, can be categorized as a single photon source or two photon source. Therefore, the thesis is divided also according to these types of quantum light sources into two parts: In the first part of the thesis, after review of the theoretical methods, which are applied in the thesis , we specifically study coupled cavities. The first cavity, pumped incoherently, performs effectively as a single photon source. We consider system-bath interaction in the coupling waveguide, i.e boson-boson interaction, for the photon occurring in the system .We demonstrate that even for a simple scenario , where thermal bath modes couple to the system, the photon statistics of the source is not completely mapped to the target system. This suggest that the environment for such a coupled systems influence the photon statistics of the source while transferring it into the target system. In the case of direct coupling of emitters to the waveguide the influence of the environment, as a dissipator, on the photon statistics can be seen in photon number distribution. Additionally, higher order correlation functions for the target system deviate drastically from the source system and show a mixture of quantum coherent and incoherent dynamics. For the case of indirect coupling of emitters to the waveguide, when the modes of two cavities are coupled, the mediating environment also influences the photon statistics of the target system. This phenomenon manifests itself in the second-order correlation function of the source and target, wherein, while the source behaves in the anti-bunched regime, the target system shows highly bunched pattern. In the second part of thesis, we study the production of two photons in nonlinear optics. As an example, we propose an optical setup where we can produce entangled pairs of photons through the dynamical Casimir effect(DCE). By applying the laser on a superconducting surface of a metal dielectric we induce a surface plasmon polariton (SPP). SPP give rise to the enhancement of DCE such as the efficiency of two photon production exceed the common nonlinear optical processes for instance parametric down conversion. We show that the resonant enhancement of the emission of two photons happens when the excitation wavelength coincides with the amplitude of the laser light. Another even more efficient source for the two photon emission is a biexciton excitation of a quantum dot. We provide a formalism for a cascaded biexciton which can be used to show how the source biexciton, pumped coherently or incoherently, influences the target biexciton through a unidirectional waveguide, modeled as a thermal bath.