An important result from quantum optics and condensed matter physics is the use of radiation-matter interaction to produce light with specific characteristics. In this work, we study a nonstationary atom-cavity system and characterize the physical properties of the emitted light. In particular we deal with a Fabry-Perot cavity with a moving mirror which has an embedded two-level system. The study of the statistical properties is done by means of the second-order correlation function with zero delay, which allows to classify the light emitted by the physical system in three different statistical regimes (Poissonian, sub-Poissonian and super-Poissonian) depending on the relationship between the variance and the mean of the photon number distribution. Therefore, in a range of parameters for which the extraction of excitations from the quantum vacuum is evident, we find that the non-classicality of the emitted light depends strongly on the relationship between the radiation-matter coupling constant and the frequency of modulation of the length of the cavity.
An important result from quantum optics and condensed matter physics is the use of radiation-matter interaction to produce light with specific characteristics. In this work, we study a nonstationary atom-cavity system and characterize the physical properties of the emitted light. In particular we deal with a Fabry-Perot cavity with a moving mirror which has an embedded two-level system. The study of the statistical properties is done by means of the second-order correlation function with zero delay, which allows to classify the light emitted by the physical system in three different statistical regimes (Poissonian, sub-Poissonian and super-Poissonian) depending on the relationship between the variance and the mean of the photon number distribution. Therefore, in a range of parameters for which the extraction of excitations from the quantum vacuum is evident, we find that the non-classicality of the emitted light depends strongly on the relationship between the radiation-matter coupling constant and the frequency of modulation of the length of the cavity.
We consider an optical cavity containing a single two-level atom driven on resonance by an external laser source.1 We focus on the limit of weak excitation where the dynamic response of this system is governed by just three parameters: the atom-field coupling constant g, spontaneous emission rate γ for the atom, and cavity decay rate κ. The statistics of the transmitted light are analyzed as a function of g, γ, and κ, in terms of the second-order correlation function g(2)(τ), and the quadrature variances measured in a homodyne detection scheme. Squeezing and photon antibunching exist over a wide range of parameters. For γ ~ κ, the system can exhibit an oscillatory response, even when the mean intracavity photon number is much less than unity.2 The oscillations can be understood in terms of the coupling between the free atom-field eigenstates |0,−>, |0,+>, and |1,−>. The oscillation frequency is determined by the energy level splitting produced between the degenerate one-quantum states |0,+> and |1,−> by the atom-field interaction. The second-order correlation function can exhibit a novel nonclassical effect, where, for g(2)(0) ≠ 0, at some finite delay τ0, the correlation function dips exactly to zero—g(2)(τ0) = 0.
We theoretically investigate the quantum statistical properties of a two-mode cavity light generated by a ∨ -type three-level atom interacting with nondegenerate subharmonic light and coupled to a two-mode squeezed vacuum reservoir. Using the master equation, we obtain steady-state expectation values for the atomic and cavity-mode operators. Based on these results, we analyze the global and local photon number variances, intensity fluctuation spectrum, joint photon number distribution, and photon count statistics. Our results reveal that squeezing parameter and subharmonic generation significantly enhance intensity fluctuations, as well as the mean and variance of photon counts, whereas atom-field coupling and cavity decay suppress them. The system exhibits super-Poissonian photon statistics, indicating that photon number fluctuations exceed the mean photon number. Furthermore, the photon count variance, which incorporates intracavity transmission and input noise, increases with detector efficiency. These results provide a comprehensive picture of photon statistics in atom-photon systems and guide the design of advanced quantum optical devices.
In this paper, we study the statistical properties of light generated by two different types of quantum emitters embedded in an optical micro-cavity. These emitters are a single quantum dot (QD) and an artificial molecule (AM), which is made by two interacting QDs. The study of the statistical properties is done by means of the second-order correlation function, which can be calculated using the elements of the density matrix operator. Some non-Hamiltonian processes are considered such as incoherent pumping of photons, spontaneous emission, decay in leaky modes, phonon assistance to the main QD, and phonon assistance to the tunnelling mechanism. The effect of each one of those mechanisms in the emission properties of the system is analysed for a certain range of parameters. As a result, we observe that the tunnelling mechanism, as well as the phonon assistance mechanism to the main QD, are processes that can favour anti-bunching in the emitted photons. For the tunnelling phonon assistance, we find that these mechanisms attest against the non-classical character of the photons, changing its statistics by increasing the value of the second-order correlation function. However, the effect of the three mechanisms acting together on the system is a net diminish of the second-order correlation function, in comparison with the same system when all the mechanisms are turned off.
A quantum optics model is considered where the cavity field interacts with two coupled atoms. The time-dependent wave function is obtained and used to derive the density matrix from which we discussed some statistical properties for the present system. The atom-atom entanglement, atoms-cavity entanglement, entropy and variance squeezing, the Pegg-Barrnet phase and the fidelity are discussed with the effects of the initial conditions, atom-atom coupling and the detuning parameter displayed. It is shown that an increase in the value of the atom-atom coupling parameter leads to an increase in the degree of entanglement. Numerical results show that under some conditions the phenomena of entanglement and the collapses and the revivals emerge. Nonclassical properties are demonstrated by means of the field quantum statistical characteristics, such as photon-number distribution, Husimi, Wigner and Glauber-Sudarshan quasidistributions and the corresponding variances.
Thermal or chaotic light sources emit radiation characterized by a slightly enhanced probability of emitting photons in bunches, described by a zero-delay second-order correlation function g((2))(0)=2. Here we explore photon-coincidence counting statistics of thermal cavities in the ultrastrong coupling regime, where the atom-cavity coupling rate becomes comparable to the cavity resonance frequency. We find that, depending on the system temperature and coupling rate, thermal photons escaping the cavity can display very different statistical behaviors, characterized by second-order correlation functions approaching zero or greatly exceeding two.
The quantum dynamics of a double quantum dot two-level system, coupled to a leaking microwave resonator mode, is theoretically investigated. The double quantum dot is driven by applying a continuous field giving rise to time-dependent modulations of its energy separation between the ground levels of each dot, forming the qubit. Therefore, the cavity resonances occur when the difference between the resonator and the qubit frequencies equals the multiple of the modulation frequency, respectively. In the strong Coulomb interaction limit and the weak couplings of the combined system, i.e. the qubit and the single-mode cavity, to corresponding electronic, phononic or photonic reservoirs, we have demonstrated that the output cavity electromagnetic field is formed of a single-photon flux obeying the sub-Poissonian quantum photon statistics. This was proved via Fano's factor behaviour or by comparing the resonator's second- and third-order photon correlation functions, respectively. The phonon, the cavity mode dephasing or the environmental temperatures influence on the quantum properties of the photons are also discussed.