Title: Engineering optomechanically induced transparency by coupling a qubit to a spinning resonator
We theoretically study the spectral properties of a pump–probe driven hybrid spinning optomechanical ring resonator optically coupled with a two-level quantum emitter (QE or qubit). Recently, we have shown [Opt. Express27,25515(2019)OPEXFF1094-408710.1364/OE.27.025515] that in the absence of the emitter, the coupled cavity version of this setup is not only capable of non-reciprocal light propagation but can also exhibit slow and fast light propagation. In this work, we investigate in what ways the presence of a single QE coupled with the optical whispering gallery modes of a spinning optomechanical resonator can alter the probe light non-reciprocity. Under the weak-excitation assumption and mean-field approximation, we find that the interplay between the rotational/spinning Sagnac effect and qubit coupling can lead to enhancement of both the optomechanically induced transparency peak value and the width of the transparency window due to the opening of a qubit-assisted backreflection channel. However, compared to the no-qubit case, we notice that such enhancement comes at the cost of degrading the group delay in probe light transmission by a factor of 1/2 for clockwise rotary directions. The target applications of these results can be in the areas of quantum circuitry and in non-reciprocal quantum communication protocols where QEs are a key component.
Ahmad, Faiz; Monk, Peter B.; Lakhtakia, Akhlesh(
, Applied Optics)
In Part I [Appl. Opt.59,1018(2020).APOPAI0003-693510.1364/AO.381246], we used a coupled optoelectronic model to optimize a thin-film AlGaAs solar cell with a graded-bandgap photon-absorbing layer and a periodically corrugated Ag backreflector combined with localized ohmic Pd–Ge–Au backcontacts, because both strategies help to improve the performance of AlGaAs solar cells. However, the results in Part I were affected by a normalization error, which came to light when we replaced the hybridizable discontinuous Galerkin scheme for electrical computation by the faster finite-difference scheme. Therefore, we re-optimized the solar cells containing ann-AlGaAs photon-absorbing layer with either a (i) homogeneous, (ii) linearly graded, or (iii) nonlinearly graded bandgap. Another way to improve the power conversion efficiency is by using a surface antireflection texturing on the wavelength scale, so we also optimized four different types of 1D periodic surface texturing: (i) rectangular, (ii) convex hemi-elliptical, (iii) triangular, and (iv) concave hemi-elliptical. Our new results show that the optimal nonlinear bandgap grading enhances the efficiency by as much as 3.31% when then-AlGaAs layer is 400 nm thick and 1.14% when that layer is 2000 nm thick. A hundredfold concentration of sunlight can enhance the efficiency by a factor of 11.6%. Periodic texturing of the front surface on the scale of 0.5–2 free-space wavelengths provides a small relative enhancement in efficiency over the AlGaAs solar cells with a planar front surface; however, the enhancement is lower when then-AlGaAs layer is thicker.
Ahmad, Faiz; Civiletti, Benjamin J.; Monk, Peter B.; Lakhtakia, Akhlesh(
, Applied Optics)
In Part I [Appl. Opt.58,6067(2019)APOPAI003-693510.1364/AO.58.006067], we used a coupled optoelectronic model to optimize a thin-film(CIGS) solar cell with a graded-bandgap photon-absorbing layer and a periodically corrugated backreflector. The increase in efficiency due to the periodic corrugation was found to be tiny and that, too, only for very thin CIGS layers. Also, it was predicted that linear bandgap-grading enhances the efficiency of the CIGS solar cells. However, a significant improvement in solar cell efficiency was found using a nonlinearly (sinusoidally) graded-bandgap CIGS photon-absorbing layer. The optoelectronic model comprised two submodels: optical and electrical. The electrical submodel applied the hybridizable discontinuous Galerkin (HDG) scheme directly to equations for the drift and diffusion of charge carriers. As our HDG scheme sometimes fails due to negative carrier densities arising during the solution process, we devised a new, to the best of our knowledge, computational scheme using the finite-difference method, which also reduces the overall computational cost of optimization. An unfortunate normalization error in the electrical submodel in Part I came to light. This normalization error did not change the overall conclusions reported in Part I; however, some specifics did change. The new algorithm for the electrical submodel is reported here along with updated numerical results. We re-optimized the solar cells containing a CIGS photon-absorbing layer with either (i) a homogeneous bandgap, (ii) a linearly graded bandgap, or (iii) a nonlinearly graded bandgap. Considering the meager increase in efficiency with the periodic corrugation and additional complexity in the fabrication process, we opted for a flat backreflector. The new algorithm is significantly faster than the previous algorithm. Our new results confirm efficiency enhancement of 84% (resp. 63%) when the thickness of the CIGS layer is 600 nm (resp. 2200 nm), similarly to Part I. A hundredfold concentration of sunlight can increase the efficiency by an additional 27%. Finally, the currently used 110-nm-thick layer ofperforms almost as well as optimal single- and double-layer antireflection coatings.
Ahmad, Faiz; Monk, Peter B.; Lakhtakia, Akhlesh(
, Applied Optics)
In Parts I [Appl. Opt.58,6067(2019)APOPAI0003-693510.1364/AO.58.006067] and II [Appl. Opt.61,10049(2022)APOPAI0003-693510.1364/AO.474920], we used a coupled optoelectronic model to optimize a thin-film CIGS solar cell with a graded-bandgap photon-absorbing layer, periodically corrugated backreflector, and multilayered antireflection coatings. Bandgap grading of the CIGS photon-absorbing layer was continuous and either linear or nonlinear, in the thickness direction. Periodic corrugation and multilayered antireflection coatings were found to engender slight improvements in the efficiency. In contrast, bandgap grading of the CIGS photon-absorbing layer leads to significant enhancement of efficiency, especially when the grading is continuous and nonlinear. However, practical implementation of continuous nonlinear grading is challenging compared to piecewise-homogeneous grading. Hence, for this study, we investigated piecewise-homogeneous approximations of the optimal linear and nonlinear grading profiles, and found that an equivalent efficiency is achieved using piecewise-homogeneous grading. An efficiency of 30.15% is predicted with a three-layered piecewise-homogeneous CIGS photon-absorbing layer. The results will help experimentalists to implement optimal designs for highly efficient CIGS thin-film solar cells.
Al-Qasimi, Asma(
, Journal of the Optical Society of America A)
The classical analogues of quantum correlations have been the subject of considerable interest in the past few years; however, all of these investigations consider the classical analogue of only pure quantum mechanical states. In this work, we studymixedclassical light states and derive relations between the polarization coherence of the field and the (classical) entanglement between its degrees of freedom. We show, for a specific model of mixed states, where the purity is determined by a single parameter, how the coherence shared between polarization and entanglement shrinks as the level of purity decreases. The sum of the square of polarization and entanglement remains constant, a behavior consistent with previous results [Phys. Rev. Lett.117,153901(2016)PRLTAO0031-900710.1103/PhysRevLett.117.153901] of pure states, even though the constant for the mixed-state case is now smaller in value.
Hancock, S. W.; Zahedpour, S.; Milchberg, H. M.(
, Optica)
A spatiotemporal optical vortex (STOV) is an intrinsic optical orbital angular momentum (OAM) structure in which the OAM vector is orthogonal to the propagation direction [Optica6,1547(2019)OPTIC82334-253610.1364/OPTICA.6.001547] and the optical phase circulates in space-time. Here, we experimentally and theoretically demonstrate the generation of the second harmonic of a STOV-carrying pulse along with the conservation of STOV-based OAM. Our experiments verify that photons can have intrinsic orbital angular momentum perpendicular to their propagation direction.
Burns, Jessica, Root, Owen, Jing, Hui, and Mirza, Imran M. Engineering optomechanically induced transparency by coupling a qubit to a spinning resonator. Journal of the Optical Society of America B 40.5 Web. doi:10.1364/JOSAB.478320.
Burns, Jessica, Root, Owen, Jing, Hui, & Mirza, Imran M. Engineering optomechanically induced transparency by coupling a qubit to a spinning resonator. Journal of the Optical Society of America B, 40 (5). https://doi.org/10.1364/JOSAB.478320
Burns, Jessica, Root, Owen, Jing, Hui, and Mirza, Imran M.
"Engineering optomechanically induced transparency by coupling a qubit to a spinning resonator". Journal of the Optical Society of America B 40 (5). Country unknown/Code not available: Optical Society of America. https://doi.org/10.1364/JOSAB.478320.https://par.nsf.gov/biblio/10405369.
@article{osti_10405369,
place = {Country unknown/Code not available},
title = {Engineering optomechanically induced transparency by coupling a qubit to a spinning resonator},
url = {https://par.nsf.gov/biblio/10405369},
DOI = {10.1364/JOSAB.478320},
abstractNote = {We theoretically study the spectral properties of a pump–probe driven hybrid spinning optomechanical ring resonator optically coupled with a two-level quantum emitter (QE or qubit). Recently, we have shown [Opt. Express27,25515(2019)OPEXFF1094-408710.1364/OE.27.025515] that in the absence of the emitter, the coupled cavity version of this setup is not only capable of non-reciprocal light propagation but can also exhibit slow and fast light propagation. In this work, we investigate in what ways the presence of a single QE coupled with the optical whispering gallery modes of a spinning optomechanical resonator can alter the probe light non-reciprocity. Under the weak-excitation assumption and mean-field approximation, we find that the interplay between the rotational/spinning Sagnac effect and qubit coupling can lead to enhancement of both the optomechanically induced transparency peak value and the width of the transparency window due to the opening of a qubit-assisted backreflection channel. However, compared to the no-qubit case, we notice that such enhancement comes at the cost of degrading the group delay in probe light transmission by a factor of 1/2 for clockwise rotary directions. The target applications of these results can be in the areas of quantum circuitry and in non-reciprocal quantum communication protocols where QEs are a key component.},
journal = {Journal of the Optical Society of America B},
volume = {40},
number = {5},
publisher = {Optical Society of America},
author = {Burns, Jessica and Root, Owen and Jing, Hui and Mirza, Imran M.},
}
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