The entanglement properties of two mode fields generated from four-wave mixing are discussed in the system an ensemble $V$-type three-level atoms embedded a two-mode cavity, which atomic transitions excited states to ground state driven by one strong and relative weak laser field, respectively. nondegenerate process occurs laser-driven transition, is also coupled cavity modes. With help auxiliary transition field adjusting frequency difference modes, highly squeezed entangled light with high...

The quantum dynamics of a compound sample consisting from semiconductor double dot (DQD) system non-linearly coupled with leaking single-mode micro-resonator is theoretically investigated. focus on the resonance condition when transition frequency equals to doubled resonator frequency, respectively, and resulting interplay among involved phonon or photon channels. As result, steady-state this complex non-linear exhibits variety possible effects that have been demonstrated here. Particularly,...

The manipulation of the steady-state behavior a collection dipole-interacting three-level atoms in $V$ or $\ensuremath{\Lambda}$ configuration is investigated as function relative phase two strong coherent driving fields. For larger samples, shown to be convenient parameter rapidly populate depopulate completely trapping state ensemble. As applications, we present appropriately prepared atomic sample an optical switching device and show its virtues controlling collective resonance...

The sub-wavelength localization of an ensemble atoms concentrated to a small volume in space is investigated. relies on the interaction with standing wave laser field. light scattered field and atom depends position relative nodes. This relation can be described by fluorescence intensity profile, which parameters, properties, modified due collective effects nearby particles. We demonstrate that profile tailored suit different setups. Finally, we apply these results two schemes. First, show...

We demonstrate that a single sub-cycle optical pulse can be generated when with few cycles penetrates through resonant two-level dense media subwavelength structure. The single-cycle gap soliton phenomenon in the full Maxwell-Bloch equations without frame of slowly varying envelope and rotating wave approximations is observed. Our study shows structure used to suppress frequency shift caused by intrapulse four-wave mixing continuous supports formation solitons even case period breaks Bragg...

The dynamics of a pair atoms can significantly differ from the single-atom if distance two is small on scale given by relevant transition wavelengths. Here, we discuss nearby three-level in $\ensuremath{\Lambda}$ configuration, and focus dependence optical properties geometry setup. We find that general transitions be dipole-dipole coupled interactions via vacuum field even their dipole moments are orthogonal. give an interpretation this effect show it may crucially influence system...

The collective spontaneous emission of a pair two coupled three-level radiators in vacuum is investigated the presence possibly intense laser field. parameters describing interaction along with population and decay rates all involved dressed states are shown to be controllable by applied In particular, populations system may transferred at will reversible way into subradiant state, allowing effective storage manipulation quantum system.

The feasibility of generating correlated photon pairs at variable frequencies is investigated. For this purpose we consider the interaction an off-resonant laser field with a two-level system possessing broken inversion symmetry. We show that generates nonclassical exhibiting strong intensity-intensity correlations. intensity applied tunes degree correlation while detuning controls frequency one photons, which can be in terahertz domain. Furthermore, observe violation Cauchy-Schwarz...

We investigate the performance of a microscopic quantum heat engine consisting V- or Lambda-type emitters interacting collectively independently when being in contact with environmental thermal reservoirs. Though efficiency Carnot's cycle is always higher than those associated these setups, we have found that cooperative may be larger V-type under similar conditions. Cooperativity among plays an important role for setup, significantly improving its performance, while less relevant engine....

We investigate control schemes for the dynamics of a collection dipole-interacting three-level atoms in $\mathrm{V}$- or $\mathrm{\ensuremath{\Lambda}}$- configuration. For this, we discuss strong-field steady-state behavior these systems under influence external parameters such as relative phase between two applied strong driving laser fields, ratio spontaneous decay and incoherent pumping rates, splitting frequency closely spaced atomic states, surrounding thermal bath. show that may act...

We investigate the generation of a strongly entangled electromagnetic field through laser pumping collection $N$ two-level atoms in two-mode optical resonator. The vacuum-multiparticle interactions enhance coupling atomic sample to cavity modes facilitating creation photons at higher frequencies. In dispersive atom-cavity limit, one can obtain steady-state output consisting tens such per mode.

Bare-state population inversion is demonstrated in a two-level system with all dipole matrix elements nonzero. A laser field resonantly driving the sample, whereas second weaker and lower frequency coherent additionally pumps it near resonance dynamically Stark-splitted states. Due to existence of differing permanent moments excited ground bare states, quantum coherences among involved dressed states are induced, leading steady state. Furthermore, large refractive indices feasible, as well...

A rich variety of quantum features can be found in a collection atoms driven only by an incoherent bath. To demonstrate this, we discuss sample three-level ladder configuration interacting via the surrounding bath, and show that fluorescence light emitted this system exhibits nonclassical properties. Realizations could thermal baths for microwave transitions, or broadband fields optical transitions. In small atoms, switched from sub- to super-Poissonian antibunching superbunching controlled...

Light scattered by a regular structure of atoms can exhibit interference signatures, similar to the classical double-slit. These first-order interferences, however, vanish for strong light intensities, restricting potential applications. Here, we show how overcome these limitations quantum in fields. First, recover fields via tailored electromagnetic bath with suitable frequency dependence. At driving, optical properties different spectral bands are distinct, thus extending set observables....

The possibility of steady-state population inversion in a small sample strongly driven two-level emitters such as quantum dots (QDs) microcavities, and its utilization towards amplification light acoustic waves, is investigated theoretically. We find that absorption spectra photons phonons crucially depend on the interplay between intrinsic vacuum phonon environments. profiles show marked novel features gain instead transparency reversed to gain, respectively. Furthermore, we report...

We investigate the coupled-system dynamics of two-level quantum dots placed on a vibrating nanomechanical resonator. The ensemble exhibits superradiance features which are transferred to mechanical degrees freedom representing fast and enhanced phonon emission in setup, resembling effect.

The resonant quantum dynamics of an excited two-level emitter is investigated via classical modulation its transition frequency while simultaneously the radiator interacts with a broadband electromagnetic field reservoir. selected to be order bare-state spontaneous decay rate. In this way, one can induce interference effects and, consequently, coherences among multiple decaying pathways. Depending on depth and absolute phase, both emission shift may conveniently modified controlled.

Coherent control and the creation of entangled states are discussed in a system two superconducting flux qubits interacting with each other through their mutual inductance identically coupling to reservoir harmonic oscillators. We present different schemes using continuous-wave fields or Stark-chirped rapid adiabatic passages, both which rely on dynamic qubit transition frequencies via external bias order maximize fidelity target states. For comparison, also special area pulse discussed. The...

The dynamics of two superconducting flux qubits coupled to each other and a common bath is discussed. We focus on the case in which qubit-qubit coupling strength dominates over respective qubit transition frequencies. derive master equation including collective effect by modeling as 1D open space this ultra-strong regime, find that greatly modifies both coherent incoherent system, giving rise qualitatively different properties. By analyzing steady-state governed equation, we show ground...

We analyze the efficiency of coherent population trapping (CPT) in a superposition ground states three-level atoms under influence decoherence process induced by broadband thermal field. show that single atom there is no perfect CPT when atomic transitions are affected The may occur only one two In case both field, we demonstrate regardless intensity field destructive effect on can be circumvented collective behavior atoms. An analytic expression was obtained for populations upper levels...

Photoionization of an atom via interatomic correlations to $N$ neighboring atoms may be strongly enhanced due constructive interference quantum pathways. The ionization proceeds resonant photoexcitation a neighbor and subsequent Coulombic decay. enhancement can scale with ${N}^{2}$, leading ``superenhanced photoionization.''

We investigate the feasibility of correlating an optical cavity field and a vibrational phonon mode. A laser pumped quantum dot fixed on nano-mechanical resonator beam interact as whole with When variables are faster than ones, we obtain final master equation describing involved modes only. Increasing temperature, that directly affects degrees freedom, one can well influence photon intensity, i.e., correlated. Furthermore, corresponding Cauchy-Schwarz inequality is violated demonstrating...

The entanglement dynamics of a laser-pumped two-level quantum dot pair is investigated in the steady-state. closely spaced emitters, embedded semiconductor substrate, interact with both environmental vacuum modes electromagnetic field reservoir as well lattice vibrational phonon thermostat. We have found that among pair's components substantially enhanced due to presence subsystem. reason induced decay symmetrical and antisymmetrical two-qubit collective states and, consequently, population...