We investigate the modifications of the frequency-comb-induced radiation pressure force on cold $^{87}$ Rb atoms that are induced by the collective effects. Collective effects include both coherent and incoherent contributions and depend on the optical thickness of the atomic cloud. We observe reduction and broadening of the comb-induced force when the cloud's optical thickness increases, and compare the measured results with predictions of a coherent model based on the timed Dicke state approach and an incoherent scattering model based on the shadow effect explained by Beer-Lambert law. Both models describe the experimental results well, indicating that an incoherent scattering approach is sufficient to explain the observed modifications of the comb-induced force even for larger optical thicknesses. The results support the analogy between the frequency comb and continuous-wave laser-atom interaction and thus pave the way toward novel frequency comb applications in laser cooling, quantum communication, and light-atom interfaces based on structured and disordered atomic systems.We investigate the modifications of the frequency-comb-induced radiation pressure force on cold $^{87}$Rb atoms that are induced by the collective effects. Collective effects include both coherent and incoherent contributions and depend on the optical thickness of the atomic cloud. We observe reduction and broadening of the comb-induced force when the cloud's optical thickness increases, and compare the measured results with predictions of a coherent model based on the timed Dicke state approach and an incoherent scattering model based on the shadow effect explained by Beer-Lambert law. Both models describe the experimental results well, indicating that an incoherent scattering approach is sufficient to explain the observed modifications of the comb-induced force even for larger optical thicknesses. The results support the analogy between the frequency comb and continuous-wave laser-atom interaction and thus pave the way toward novel frequency comb applications in laser cooling, quantum communication, and light-atom interfaces based on structured and disordered atomic systems.

Bulletin of the American Physical SocietyJan 20, 20210 citations

Spontaneously generated coherence in a four-level atomic system under induced chirality: Quantum control of the Casimir force

Rashid Ahmad, Hazrat Ali, Iftikhar Ahmad +1 more

In this work, we investigate the coherent control of the Casimir force (CF) in a four-level atomic system under electromagnetically induced chirality. Therefore, we consider two parallel slabs of finite length in a quantum vacuum composed of ensembles of cesium vapor atoms in a four-level double Λ-type atomic configuration. By the use of the quantum interference (QI) effect which arises from the cross-coupling between the different spontaneous emission pathways, we demonstrate that it is possible to fully control the CF in the system via the spontaneously generated coherence (SGC) and the relative phase between the electromagnetic fields. In fact, we first show that the chirality in the atomic system can be induced by the SGC and the probe detuning, satisfying the passivity conditions. Next, we manipulate and control the QI in the system by changing the angle between the dipole moments, as the SGC is sensitive to their relative orientations. Besides, we explore the dependence of the Casimir interaction energy on the relative phase of the control fields. Finally, we observe that the Casimir interaction energy can be switched from negative to positive for a specific given phase value.In this work, we investigate the coherent control of the Casimir force (CF) in a four-level atomic system under electromagnetically induced chirality. Therefore, we consider two parallel slabs of finite length in a quantum vacuum composed of ensembles of cesium vapor atoms in a four-level double Λ-type atomic configuration. By the use of the quantum interference (QI) effect which arises from the cross-coupling between the different spontaneous emission pathways, we demonstrate that it is possible to fully control the CF in the system via the spontaneously generated coherence (SGC) and the relative phase between the electromagnetic fields. In fact, we first show that the chirality in the atomic system can be induced by the SGC and the probe detuning, satisfying the passivity conditions. Next, we manipulate and control the QI in the system by changing the angle between the dipole moments, as the SGC is sensitive to their relative orientations. Besides, we explore the dependence of the Casimir interaction energy on the relative phase of the control fields. Finally, we observe that the Casimir interaction energy can be switched from negative to positive for a specific given phase value.

Results in PhysicsMar 1, 202313 citations

Quantum coherence resonance

裕也中尾, Hiroya Nakao

Apr 1, 20210 citations

Forced indistinguishability in ‘‘induced coherence without stimulated emission’’

G. A. Barbosa

The nonclassical phenomenon of ``induced coherence without simulated emission'' is analyzed under the condition where two nonlinear ${\mathrm{\ensuremath{\chi}}}^{(2)}$ crystals are aligned in such a way that their idler emissions are collinear and inside a ringlike cavity with loss. This forced indistinguishability of the idler photons produces an interference between the free traveling conjugated signal beams when they are superposed. This interference is independent of the cavity loss, within the limits of a single-mode theory, and highly dependent on the position of the crystals inside the cavity. The maximum obtainable visibility of 100% reflects an induced coherence in the two crystals by the cavity field.The nonclassical phenomenon of ``induced coherence without simulated emission'' is analyzed under the condition where two nonlinear ${\mathrm{\ensuremath{\chi}}}^{(2)}$ crystals are aligned in such a way that their idler emissions are collinear and inside a ringlike cavity with loss. This forced indistinguishability of the idler photons produces an interference between the free traveling conjugated signal beams when they are superposed. This interference is independent of the cavity loss, within the limits of a single-mode theory, and highly dependent on the position of the crystals inside the cavity. The maximum obtainable visibility of 100% reflects an induced coherence in the two crystals by the cavity field.

Physical Review AOct 1, 19944 citations

Coherence and Quantum Mechanics

Stephan Zanzinger

NATO ASI series. Series B : PhysicsJan 1, 19913 citations

We investigate the modifications of the frequency-comb-induced radiation pressure force on cold

^{87}

Rb atoms that are induced by the collective effects. Collective effects include both coherent and incoherent contributions and depend on the optical thickness of the atomic cloud. We observe reduction and broadening of the comb-induced force when the cloud's optical thickness increases, and compare the measured results with predictions of a coherent model based on the timed Dicke state approach and an incoherent scattering model based on the shadow effect explained by Beer-Lambert law. Both models describe the experimental results well, indicating that an incoherent scattering approach is sufficient to explain the observed modifications of the comb-induced force even for larger optical thicknesses. The results support the analogy between the frequency comb and continuous-wave laser-atom interaction and thus pave the way toward novel frequency comb applications in laser cooling, quantum communication, and light-atom interfaces based on structured and disordered atomic systems.