Optical and microwave control of resonance fluorescence and squeezing spectra in a polar molecule

Abstract

A two-level quantum emitter with broken inversion symmetry simultaneously driven by an optical field and a microwave field that couples to the permanent dipole's moment is presented. We focus to a situation where the angular frequency of the microwave field is chosen such that it closely matches the Rabi frequency of the optical field, the so-called Rabi resonance condition. Using a series of unitary transformations we obtain an effective Hamiltonian in the double-dressed basis which results in easily solvable Bloch equations which allow us to derive analytical expressions for the spectrum of the scattered photons. We analyze the steady-state population inversion of the system which shows a distinctive behavior at the Rabi resonance with regard to an ordinary two-level nonpolar system. We show that saturation can be produced even in the case that the optical field is far detuned from the transition frequency, and we demonstrate that this behavior can be controlled through the intensity and the angular frequency of the microwave field. The spectral properties of the scattered photons are analyzed and manifest the emergence of a series of Mollow-like triplets which may be spectrally broadened or narrowed for proper values of the amplitude and/or frequency of the low-frequency field. We also analyze the phase-dependent spectrum which reveals that a significant enhancement or suppression of the squeezing at certain sidebands can be produced. These quantum phenomena are illustrated in a recently synthesized molecular complex with high nonlinear optical response although they can also occur in other quantum systems with broken inversion symmetry.

Role of generalized parity in the symmetry of the fluorescence spectrum from two-level systems under periodic frequency modulation

“…Specifically, the spectrum is expected to be symmetric when δ = 0 and asymmetric when δ = 0. This is consistent with the findings of previous studies [26,27,37]. For the multiharmonic modulation f (t) = N p=1 Ω z,p cos(pω z t + φ p )], where Ω z,p and φ p are the amplitude and phase of the pth harmonic, respectively, either f (t) = −f (t + T /2) or f (t) = −f (t + T /2) can be met, similarly to the biharmonic case.…”

“…We address the symmetry and asymmetry of the spectrum by considering the generalized parity of Floquet states rather than the behaviors of the bare-state or dressed-state populations as considered in Refs. [26,46,49]. The generalized parity is found to guarantee the symmetry of the spectrum while the breaking of such a parity can yield pronouncedly asymmetric spectrum even in the vanishing detuning case.…”

“…This is a generalized model as compared with the previous one considered in Refs. [25,26,37]. To study the emission processes, we need to take account of the spontaneous decay.…”

“…As is well-known, for a sufficiently strong monochromatic field, the spectrum has a symmetric three-peak structure, known as the Mollow triplet [1]. More recently, the bi-and multi-chromatically driven quantum systems are of interest [25][26][27][28]. In such systems, the spectrum turns out to have a complicated multipeak structure [7][8][9][10][11][12][13], which can be either symmetric or asymmetric.…”

Dynamics of a quantum oscillator coupled with a three-level Λ-type emitter

“…In this context, quantum systems possessing permanent dipoles were shown to generate terahertz light [30][31][32][33][34]. Additionally, they exhibit bare-state population inversion as well as multiple spectral lines and squeezing [35][36][37]. * Electronic address: macovei@phys.asm.md Thus, there is an increased interest for novel quantum systems exhibiting lasing in a broad parameter range or cooling of micro-or nano-scale devices.…”