Fuzzy scheduling of job orders in a two-stage flowshop with batch-processing machines

In this paper, we present a mixed-integer fuzzy programming model and a genetic algorithm (GA) based solution approach to a scheduling problem of customer orders in a mass customizing furniture industry. Independent job orders are grouped into multiple classes based on similarity in style so that the required number of setups is minimized. The family of jobs can be partitioned into batches, where each batch consists of a set of consecutively processed jobs from the same class. If a batch is assigned to one of available parallel machines, a setup is required at the beginning of the first job in that batch. A schedule defines the way how the batches are created from the independent jobs and specifies the processing order of the batches and that of the jobs within the batches. A machine can only process one job at a time, and cannot perform any processing while undergoing a setup. The proposed formulation minimizes the total weighted flowtime while fulfilling due date requirements. The imprecision associated with estimation of setup and processing times are represented by fuzzy sets.     

Fine tuning of a triply resonant OPO for generating frequency degenerate CV entangled beams at low pump powers

A method of achieving triple resonance in a frequency-degenerate but polarization-non-degenerate optical parametric oscillator (OPO) with external mirrors is illustrated. The OPO is brought to the triple-resonance condition by tuning the non-linear crystal temperature and tilting the cavity axis. The interplay among temperature and tilting mismatch and gain is analyzed together with the allowed ranges of variation of these parameters. The method has been successfully applied to an OPO based on a periodically poled KTP crystal. Calibration of the system is reported together with parametric gain and squeezing measurements below threshold as a test of reliability and efficiency. PACS 42.50.-p; 42.65.-k     

Interaction of a two-level atom with squeezed light

We consider a degenerate parametric oscillator whose cavity contains a two-level atom. Applying the Heisenberg and quantum Langevin equations, we calculate in the bad-cavity limit the mean photon number, the quadrature variance, and the power spectrum for the cavity mode in general and for the signal light and fluorescent light in particular. We also obtain the normalized second-order correlation function for the fluorescent light. We find that the presence of the two-level atom leads to a decrease in the degree of squeezing of the signal light. It so turns out that the fluorescent light is in a squeezed state and the power spectrum consists of a single peak only.     

Degenerate three-level cascade laser with the cavity mode driven by coherent light

We present the quantum statistical properties of the light produced by a degenerate three-level cascade laser with the cavity mode driven by coherent light. In this system three-level atoms in a cascade configuration, initially prepared in a coherent superposition of the top and bottom levels, are injected into a cavity coupled a vacuum reservoir. We find that although the driving coherent light has no effect on the degree of squeezing, it increases the mean photon number considerably. Therefore, this quantum optical system can be taken as a source of a bright squeezed light.     

A degenerate three-level laser with a parametric amplifier

The aim of this paper is to study the squeezing and statistical properties of the light produced by a degenerate three-level laser whose cavity contains a degenerate parametric amplifier. In this quantum optical system the top and bottom levels of the three-level atoms injected into the laser cavity are coupled by the pump mode emerging from the parametric amplifier. For a linear gain coefficient of 100 and for a cavity damping constant of 0.8, the maximum intracavity squeezing is found at steady state and at threshold to be 93%.     

Entanglement of two spatially separated qubits via correlated photons

We show that a high degree of steady-state entanglement between two spatially separated and initially uncoupled qubits can be achieved via interaction with a quantized squeezed field in a cavity. The cavity field induces two-photon coherence, which is crucial in creating entanglement between the qubits. Optimum entanglement is obtained when the less dissipative qubit is incoherently pumped while the other dissipates the excitation. Given the current state-of-the-art in cavity quantum electrodynamics and squeezed light sources, our scheme presents an effective way for light-to-matter entanglement transfer.     

Enhanced squeezing and entanglement in a non-degenerate three-level cascade laser with injected squeezed light

We consider a non-degenerate three-level cascade laser coupled to a two-mode squeezed vacuum reservoir via the lossy single-port mirror. Applying the pertinent master equation, we analyze the effects of the injected squeezed light on the quadrature squeezing, entanglement and normalized intensity difference fluctuations. We show that the injected squeezed light considerably enhances the degree of squeezing and entanglement in the two-mode light for certain initial conditions. Moreover, the injected squeezed light increases the mean photon number where the squeezing and entanglement is significant. We also show that the presence of the injected squeezed light greatly reduces the noise in the intensity difference.     

Bright entangled light from two-mode cascade laser

We show that a two-mode three-level cascade laser driven by external coherent fields generate intense entangled light. It turns out that external driving fields which are at resonance with the cavity modes substantially improve the intensity of the two-mode light in the cavity in a region where the squeezing and entanglement is significant making the system under consideration a viable source of bright squeezed as well as entangled light.