The quantum properties of a collection of dipole-interacting three-level V - and Λ-type atoms are investigated in the presence of external coherent sources and a thermal bath. It is demonstrated that both the steady-state collective populations and the spectral features of these samples can be manipulated by varying the temperature or especially the atomic-level spacings by, e.g. , static magnetic fields.
The quantum properties of a collection of dipole-interacting three-level V - and Λ-type atoms are investigated in the presence of external coherent sources and a thermal bath. It is demonstrated that both the steady-state collective populations and the spectral features of these samples can be manipulated by varying the temperature or especially the atomic-level spacings by, e.g. , static magnetic fields.
We investigate control schemes for the dynamics of a collection of dipole-interacting three-level atoms in V- or $\mathrm{\ensuremath{\Lambda}}$- configuration. For this, we discuss the strong-field steady-state behavior of these systems under the influence of external parameters such as the relative phase between the two applied strong driving laser fields, the ratio of spontaneous decay and incoherent pumping rates, the splitting frequency between closely spaced atomic states, or a surrounding thermal bath. We show that these may act as convenient tools to sensitively control the collective dynamics of the atoms. As applications, we analyze the fluorescence and absorption properties of the atomic samples. Finally, we discuss the transient behavior to show that the presented schemes feature a rapid system evolution as required for many applications.
The manipulation of the steady-state behavior of a collection of dipole-interacting three-level atoms in a V or Lambda configuration is investigated as a function of the relative phase of two strong coherent driving fields. For larger samples, the phase is shown to be a convenient parameter to rapidly populate or depopulate completely a trapping state of the ensemble. As applications, we present the appropriately prepared atomic sample as an optical switching device and show its virtues in controlling the collective steady-state resonance fluorescence intensity.
We investigate the resonance fluorescence from a collection of three-level V- or Λ-type atoms which are driven simultaneously by coherent and incoherent sources of light. In particular, we focus on interference effects arising from broadband incoherent pump fields. This interference, which does not require non-orthogonal transition dipole moments, induces a sensitivity to the relative phase of the coherent driving fields. It is shown that the variation of the relative phase leads to interesting modifications of the collective steady-state behaviors of the two systems.
Coherent population trapping effect is widely studied for simple three-level systems of different types ((Xi) 2, (Lambda) , V)1,2. For real atoms the situation is more complicated. Atomic levels are degenerated one and in the presence of external fields coupling of magnetic sublevels appears due to radiation, so magnetic fields leading to the systems of levels of the higher order. Our theory and method of calculation for interaction of multilevel atoms, with intense radiation fields in the presence of external magnetic fields have been applied for considering coherent population trapping effect for such systems. In the absence of magnetic field for considering sets of parameters, we can see the behavior of populations in function of time, detunings for both systems of coupled sublevels inherent to the coherent population trapping effect. In the presence of magnetic field, we can see novel features in the populations for the systems of coupled magnetic sublevels.
ABSTRACT We investigate the steady-state properties and dynamics of a three-level cascade atom interacting with a thermal light field, focusing on how ther mal photon occupation affects population distributions, coherence decay, and fluorescence spectra. Using a rate-equation model and analytical ex pressions for the steady-state populations, we examine the time evolution of the atomic populations under low, intermediate, and high thermal pho ton numbers ¯n. At intermediate ¯n, a balance between spontaneous emis sion and thermal absorption emerges, yielding nonzero stable populations at all levels; conversely, for low ¯n, spontaneous emission dominates, and the system rapidly decays to the ground state. We also investigate the degradation of coherence |ρfe(t)| between the upper and intermediate lev els. At high thermal photon numbers, thermalization drives the system toward equipartition, such that the populations of all levels become nearly equal. We show that increasing thermal occupation shortens the life time of quantum superpositions and accelerates decoherence, as evidenced by the loss of |ρfe(t)|. In the steady-state fluorescence spectrum of the |e〉 → |g〉 transition, Lorentzian broadening, proportional to the effective decoherence rate, highlights the influence of thermal photons on phase co herence and spectral features. These findings have direct implications for quantum information processing: they demonstrate how thermal noise markedly degrades coherence, gate fidelity, and photon emission quality. Keywords: population distribution; three-level cascade atom; thermal light field; steady state population; rate-equation model; coherence decay. vii
ABSTRACT We investigate the steady-state properties and dynamics of a three-level cascade atom interacting with a thermal light field, focusing on how ther mal photon occupation affects population distributions, coherence decay, and fluorescence spectra. Using a rate-equation model and analytical ex pressions for the steady-state populations, we examine the time evolution of the atomic populations under low, intermediate, and high thermal pho ton numbers ¯n. At intermediate ¯n, a balance between spontaneous emis sion and thermal absorption emerges, yielding nonzero stable populations at all levels; conversely, for low ¯n, spontaneous emission dominates, and the system rapidly decays to the ground state. We also investigate the degradation of coherence |ρfe(t)| between the upper and intermediate lev els. At high thermal photon numbers, thermalization drives the system toward equipartition, such that the populations of all levels become nearly equal. We show that increasing thermal occupation shortens the life time of quantum superpositions and accelerates decoherence, as evidenced by the loss of |ρfe(t)|. In the steady-state fluorescence spectrum of the |e〉 → |g〉 transition, Lorentzian broadening, proportional to the effective decoherence rate, highlights the influence of thermal photons on phase co herence and spectral features. These findings have direct implications for quantum information processing: they demonstrate how thermal noise markedly degrades coherence, gate fidelity, and photon emission quality. Keywords: population distribution; three-level cascade atom; thermal light field; steady state population; rate-equation model; coherence decay. vii