Entanglement and coherence in a hybrid Laguerre–Gaussian rotating cavity optomechanical system with two-level atoms

Abstract

We theoretically investigate quantum entanglement and coherence in a hybrid Laguerre-Gaussian rotating cavity optomechanical system with two-level atoms, where cavity and mechanical modes are coupled through the exchange of orbital angular momentum. Our study shows that the injection of atoms with a suitable choice of the physical parameters can significantly improve the degree of optomechanical entanglement in all aspects. In the study of quantum coherence research, we show more comprehensively the negative and positive effects of atoms on the coherence. The result obtained is that only when the atom is significantly offresonant to driving field, the coupling strength in between the atoms and light field increases and the quantum coherence can be enhanced, otherwise it will reduce quantum coherence. In addition, the atomic decay suppresses quantum coherence phenomenon.

Rotational mirror–mirror entanglement via dissipative atomic reservoir in a double-Laguerre–Gaussian-cavity system

“…By changing l from 200 to 500, the entanglement disappears at κ/γ = 0.2, 0.088, 0.05, 0.03, respectively. When the cavity losses are comparable to the atomic damping rates, the entanglement would be vanished, which is different from the results presented in [65]. What's more, the effects of thermal noise on quantum entanglement are also discussed in figure 8.…”

“…In the first of place, in our work, we find that the entanglement is essentially originated from the dissipative atomic reservoir and the transfer processes between cavity modes and mirrors. This is in contrast with previous schemes [64,65], wherein the hybrid entanglement happens based on the parametric interaction under appropriate conditions, without which not only the tripartite entanglement but also the bipartite entanglement is impossible to realize. Specifically, in [65], the two-level atoms are injected into the cavity to enhance the cavity-mirror entanglement by choosing proper parameters rather than to prepare entanglement.…”

“…As a result, the bipartite photon-photon entanglement is essentially established by the atomic reservoir effects and then it is transferred to two macroscopic rotating mirrors at δ j = ω ϕ j via the two transfer processes a j ↭ b j . Finally, it is worthwhile to point out that the present system is completely different from the previous schemes proposed in [65]. In their works, the two-level atomic ensemble or magnon is placed into the cavity to enhance the cavity-mirror entanglement or to realize the tripartite entanglement based on the parametric interaction.…”

“…Later, by placing a yttrium iron garnet (YIG) sphere into the LG cavity, the tripartite entanglement are generated between cavity mode, mirror and magnon [64]. While the YIG sphere is replaced by a two-level atomic ensemble, the cavity-mirror entanglement and quantum coherence are enhanced by choosing suitable parameters [65], which is attributed to the fact that the effective coupling of the parametric interaction is enhanced by injecting the atoms. Nevertheless, the quantum coherence would be spoiled when the large detuning limit is not satisfied.…”

A rotational-cavity optomechanical system with two revolving cavity mirrors: optical response and fast-slow light mechanism

“…Subsequently, Liu et al also accomplished the ground-state cooling of the rotating mirror in a double L-G cavity with atomic ensemble [58]. These studies on the ground cooling of the rotating mirror have provided many opportunities to further investigate macroscopic quantum phenomena in rotational cavity optomechanical systems, including bipartite quantum entanglement [57,[60][61][62] and tripartite quantum entanglement [63], macroscopic quantum coherence [64], OMIT phenomena [65][66][67][68][69][70], and its applications for the measurement of orbital angular momentum [65,71,72], higher order sideband generation [73,74] and phase-matching analysis [75]. However, compared to studies on conventional optomechanical systems, the research on the double-OMIT phenomenon in this type of rotating cavity optomechanical system is still essentially very limited.…”