One of the platforms for implementing Quantum technologies is optical systems where the cavity is a major component. Furthermore, state estimation has a significant role in understanding the behavior and control of Quantum systems. This paper concerns derivation of Quantum-filtering equations for a one-sided cavity driven by the field in the vacuum state. To this end, the number operator has been selected as an appropriate observable for the cavity. Then, filtering equations, namely stochastic master equation, have been derived considering observations which are measured by monitoring the output field either by Homodyne or photon detector. In addition, the effect of changing cavity parameters has been investigated on its behavior. Finally, the accuracy of the result has been validated by simulating the derived stochastic master equations and comparing with the master equation.

In cavity opto-mechanical cooling, driving laser optical field, exerts extra decay to the mechanical mode of cavity, and cause a return to the ground state. In this study, Quantum cooling of an opto-mechanical cavity in contact with a thermal bath, has been simulated by using Quantum Toolbox in Python “QuTiP”. Simulation results show that, the cavity cooling process, takes more time with increasing the decay rate of optical modes and go faster with increasing the decay rate of mechanical modes. Also this process takes less time with the increasing coupling constant of optical and mechanical modes. By adding a qubit to the system, simulation shows that the cooling process could happen faster in compare to the previous.

A nanosystem containing a Quantum dot within an optical cavity is a platform for the study of important Quantum phenomena such as photon antibunching, entanglement, single photon generation, and Quantum information. The use of such a system in these technologies depends on achieving a strong coupling mode between the Quantum dot and the optical cavity. In this study, using a Quantum optical approach, the energy Eigen values of a system including a Quantum dot within an optical cavity were calculated. Then, for different Quantum dots and optical cavities, the threshold conditions were studied to achieve strong coupling mode. The results showed that with increasing the coupling constant, the energy levels splitting increases and the threshold conditions are more favorable for achieving strong coupling mode. The energy level splitting threshold for the Quantum dot with a decay rate of 2 μ, eV within optical cavities with a decay rate of 45 to 205 μ, eV occurred at a coupling constant of 10. 75 to 50. 75 μ, eV. In fact, it was observed that in order to achieve a strong coupling mode in such systems, it is necessary to go to the engineering of cavities with lower decay rates because the change in Quantum dots does not have a significant effect on achieving this goal. Also, in a system with such a Quantum dot, which has a coupling constant of 35 μ, eV within an optical cavity with energies of 20 to 140 μ, eV, the quality factor is in the range of 4930 to 5060.

In this paper we give an introduction to the ideas of Quantum thermodynamics, using only basic concepts from Quantum and statistical mechanics. Then, we discuss the framework of non-equilibrium processes in Quantum systems and introduce how to calculate quantities such as work and irreversible entropy in these processes. We then apply these results to the problem of atom-cavity system while their interaction describe by Jaynes-Cummings model with both weak and strong atom-cavity coupling. Here, we introduce the concept of Quantum thermodynamics of close Quantum system and so by considering a good cavity, coupling of cavity modes with its reservoir has been omitted.

Currently, carbon Quantum dots have attracted considerable attention due to their unique properties and desirable advantages. High crystallinity, water solubility, good dispersibility, small size, low toxicity, inexpensive raw materials, high chemical stability, environmental compatibility, low cost, stability under light, desirable charge transfer with advanced electronic conductivity, as well as specific thermal and mechanical properties are some of these features. Carbon Quantum dots have various applications in different fields. Fabrication of precise chemical and biological sensors, bioimaging, solar cells, drug tracking, nanomedicine, light-emitting diodes (LEDs), and electrocatalysts are some of these applications. Biological sensors based on carbon Quantum dots are capable of detecting various metal ions, acids, proteins, biotin, polypeptides, DNA and miRNA, water pollutants, hematin, drugs, vitamins, and other chemicals. In the present study, the properties of carbon Quantum dots and some of their fabrication and applications methods have been addressed. In continuation of the paper, the effect of carbon Quantum dots on important factors in plants such as growth and development, photosynthesis, absorption and transportation of substances, resistance to biotic and abiotic stresses, as well as their application in agriculture has been investigated.

The aim of this study is to investigate dynamical properties of a two-mode f-deformed cavity- field ‎coupled to an effective two-level atom with and without the rotating wave approximation. The first ‎section discusses the theoretical model of the interaction between a two-mode cavity-field and an ‎effective two-level atom within the framework of an f-DJCM without the rotating wave ‎approximation. After that, we obtain the reduced density matrix of the cavity-field with and without ‎the rotating-wave approximation. Then, we have investigated the effect of the counter-rotating ‎terms on temporal evolution of various non-classical properties of the cavity-field, i.e., photon-‎counting statistics, the cross correlation between the modes of the field, and the Quantum ‎fluctuations of the quadrature components. Particularly, we compare the numerical result for three ‎different values of the deformation parameter q (q=1, q=1.1, q=0.9) with and without applying the rotating ‎wave approximation. By using of the numerical method, we concluded that even under the ‎condition in which the RWA is considered to be valid, there are the significant effects of virtual-‎photon field on the photon-counting statistics, the cross correlation between the modes of the ‎field, and the Quantum fluctuations of the quadrature components‎.

We present a theoretical interacting one-dimensional Bose-Einstein condensate (BEC) inside an optical cavity which is driven through of the fixed end mirrors. Under the Bogoliubov approximation and when the number of photons inside the cavity is not too large, the atomic field operator can be considered as a single-mode Quantum field which is coupled to the radiation pressure of the intracavity field. In this way, the system behaves like an optomechanical system with an extra nonlinear term corresponding to the atom-atom interaction. We show that one of the best ways of tracing the effect of atomic interaction is to study the noise power spectrum of the field of the cavity. For this purpose, we study the light intensity spectrum of the cavity as well as the entanglement between the optical cavity and the BEC. We show how the pattern of the power spectrum of the cavity changes due to the nonlinear effect of atomic collisions. Furthermore, it is shown that due to the s-wave scattering frequency of the atom-atom interaction, one can measure the strength of interatomic interaction. Besides, we show how the atomic collisions affect the entanglement between subsystems and cooling behavior of the BEC atoms.

In this paper, by considering a system consisting of a single two-level trapped ion interacting with a single-mode quantized radiation field inside a lossless cavity, the temporal evolution of the ionic and the cavity-field Quantum statistical properties including photon-counting statistics, Quantum fluctuations of the field quadratures and Quantum fluctuations of the ionic dipole variables are investigated. It is found that in the Lamb-Dicke limit it is possible for the cavity-field to evolve into a non classical state (squeezed state or state with sub-Poissonian statistics) and this possibility is solely affected by the internal and external Quantum dynamics of the ion. Also it is found that the dipole squeezing may occur in the dynamics of the trapped ion which sensitively depends on Quantum statistics of the cavity-field.

In this paper, for the first time, the dynamic characteristics of optical injection locking vertical cavity surface emitting laser (OIL-QD-VCSEL) are investigated theoretically. By using the rate equations for dynamics of electrons and holes at GaAs barrier, wetting layer (WL), and three discrete QD levels and the heat equation, turn-on dynamics and also the small and large signal responses of laser without optical injection are numerically simulated. By adding the equations for the amplitude and phase of the QD-VCSEL field to the system of equations, the dynamic characteristics of optical injected laser are calculated. It is shown that due to optical injection, the electron and hole dynamics in QDs are synchronized, the modulation frequency is enhanced, the chirp is significantly reduced and QD-VCSEL manifests a high performance at the repetition frequency more than relaxation oscillation frequency (about 22 GHz).