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npj Nanophotonics

Dynamic quantum-light radiation shaping with time-modulated BTO-driven nanoantennas array

Achiles F. da Mota, Mohammad Mojtaba Sadafi, Hossein Mosallaei

Published Jun 21, 2026• 0 citations
Publisher

Abstract

Quantum nanophotonics enables advanced functionalities in information processing and sensing by providing control over quantum-light emission. Introducing time modulation into nanophotonic environments adds an additional dimension, enabling dynamic reconfiguration of the local density of optical states (LDOS), access to Floquet harmonics, and simultaneous control of emission rate, spectrum, and direction, capabilities that are fundamentally inaccessible in static platforms. Designing such systems requires self-consistent treatment of temporal modulation, electrodynamics, and quantum dynamics. Here, we extend a quantum-electromagnetic framework by coupling time-modulated Maxwell electrodynamics, solved using an anisotropic discrete dipole approximation, with a harmonic-resolved Gorini–Kossakowski–Sudarshan–Lindblad master equation. This Floquet–Lindblad–DDA approach captures the quantum feedback induced by temporal modulation and enables evaluation of harmonic-resolved populations, radiated and dissipated power, Purcell enhancement, and quantum efficiency. We applied the method to control the emission of a diamond NV center using voltage-driven Pockels modulation of a barium titanate nanoantenna array. The optimized structure achieves Purcell enhancements exceeding 5000 and routes more than 75% of the power to the n = +1 Floquet harmonic, enabling electronic beam steering by more than 50°. These results demonstrate a platform for programmable quantum-light emission based on time-modulated nanophotonics.

DOI
10.1038/s44310-026-00141-5

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Quantum nanophotonics enables advanced functionalities in information processing and sensing by providing control over quantum-light emission. Introducing time modulation into nanophotonic environments adds an additional dimension, enabling dynamic reconfiguration of the local density of optical states (LDOS), access to Floquet harmonics, and simultaneous control of emission rate, spectrum, and direction, capabilities that are fundamentally inaccessible in static platforms. Designing such systems requires self-consistent treatment of temporal modulation, electrodynamics, and quantum dynamics. Here, we extend a quantum-electromagnetic framework by coupling time-modulated Maxwell electrodynamics, solved using an anisotropic discrete dipole approximation, with a harmonic-resolved Gorini–Kossakowski–Sudarshan–Lindblad master equation. This Floquet–Lindblad–DDA approach captures the quantum feedback induced by temporal modulation and enables evaluation of harmonic-resolved populations, radiated and dissipated power, Purcell enhancement, and quantum efficiency. We applied the method to control the emission of a diamond NV center using voltage-driven Pockels modulation of a barium titanate nanoantenna array. The optimized structure achieves Purcell enhancements exceeding 5000 and routes more than 75% of the power to the n = +1 Floquet harmonic, enabling electronic beam steering by more than 50°. These results demonstrate a platform for programmable quantum-light emission based on time-modulated nanophotonics.
We study the dynamics of strongly coupled nanophotonic systems with time-variable parameters. The approximate analytic solutions are obtained for a broad class of open quantum systems including a two-level fermion emitter strongly coupled to a multimode quantized electromagnetic field in a cavity with time-varying cavity resonances or the electron transition energy. The coupling of the fermion and photon subsystems to their dissipative reservoirs is included within the stochastic equation of evolution approach, which is equivalent to the Lindblad approximation in the master equation formalism. The analytic solutions for the quantum states and the observables are obtained under the approximation that the rate of parameter modulation and the amplitude of the frequency modulation are much smaller than the optical transition frequencies. At the same time, they can be arbitrary with respect to the generalized Rabi oscillation frequency, which determines the coherent dynamics. Therefore, our analytic theory can be applied to an arbitrary modulation of the parameters, both slower and faster than the Rabi frequency, for complete control of the quantum state. In particular, we demonstrate protocols for switching on and off the entanglement between the fermionic and photonic degrees of freedom, swapping between the quantum states, and the decoupling of the fermionic qubit from the cavity field due to modulation-induced transparency.
Strong periodic driving of cavity-quantum electrodynamics (QED) in the ultrastrong-coupling regime creates nonequilibrium states whose dissipation is governed by Floquet quasienergies rather than undriven dressed resonances. However, modeling such a regime is a significant theoretical challenge, including a number of subtle problems such as the need to ensure gauge invariance for truncated matter-cavity systems with time-dependent driving. To fill this theoretical gap, we introduce a nonsecular Floquet generalized master equation framework for strongly driven open cavity-QED systems, formulated in the dressed basis of the quantum Rabi model and applicable to structured reservoirs without rotating-wave approximations. Our theory can thus model Floquet-driven dynamics in open ultrastrong-coupling cavity-QED, and demonstrates a wide range of quantum state control. Using strong optical pumping and parametric mechanical modulation, we compute long-time populations, fluorescence spectra, and the Floquet-Liouville eigenspectra, resolving observable resonances into hybridized quasienergy channels and decay rates. By systematically comparing with conventional time-independent dressed-basis generalized master equations, we show that static approaches only reproduce steady-state populations in restricted excitation regimes, and fail for frequency-resolved observables and break down under appropriate Floquet engineering, surprisingly, even for spectrally flat baths. Structured environments, such as Lorentzian-Ohmic reservoirs, further amplify these discrepancies through sideband-selective decay. Our results demonstrate that dissipation in driven ultrastrong cavity-QED is intrinsically quasienergy resolved and we establish Floquet-dissipative theory as an accurate and powerful framework for predicting spectra, controlling decay pathways, and engineering nonequilibrium quantum states and reservoirs.
Cavity quantum electrodynamics is the art of enhancing light-matter interaction of photon emitters in cavities with opportunities for sensing, quantum information, and energy capture technologies. To boost emitter-cavity interaction, that is, coupling strength g, ultrahigh quality cavities have been concocted yielding photon trapping times of microsecondsy to milliseconds. However, such high- Q cavities give poor photon output, hindering applications. To preserve high photon output, it is advantageous to strive for highly localized electric fields in radiatively lossy cavities. Nanophotonic antennas are ideal candidates combining low- Q factors with deeply localized mode volumes, allowing large g, provided the emitter is positioned exactly right inside the nanoscale mode volume. Here, with nanometer resolution, we map and tune the coupling strength between a dipole nanoantenna-cavity and a single molecule, obtaining a coupling rate of g max ∼ 200 GHz. Together with accelerated single photon output, this provides ideal conditions for fast and pure nonclassical single photon emission with brightness exceeding 10 9 photons/sec. Clearly, nanoantennas acting as “bad” cavities offer an optimal regime for strong coupling g to deliver bright on-demand and ultrafast single photon nanosources for quantum technologies.
Optomechanics is the study of the interaction between nano-objects and light fields through radiation pressure. Recent sophisticated optomechanical systems consist of strongly coupled mechanical and optical resonators and are made using semiconductor nanofabrication techniques. Although the optomechanical systems have exhibited their powerful capability of controlling photons, they are scarcely used to control the solid-state artificial atoms that emit photons. The main reason is that an efficient coupling mechanism remains unexplored. Here, we hybridize a silicon-integrated optomechanical resonator with two-level atom-like emitters to demonstrate an optomechanical cavity quantum electrodynamic (cQED) effect. With this system and the effect, we realize the dynamic modulation of the spontaneous emission rate. We choose copper dopants in silicon as the emitters for its narrow linewidth (0.3 nm) and long lifetime ( ∼ 30 n s ). Our judiciously designed coupled-nanobeam optomechanical resonator achieves a strong Purcell effect and high cavity-modulation performances. The optical cavity of the optomechanical resonator is dynamically coupled to the emission line and, as a result, on-demand sharp pulses (up to 9.5-fold intensity enhancement and 3.5 ns in duration, which is one ninth of the emission lifetime) appear along the photoluminescence decay. These experimental results are exactly explained with an analytical model that combines optomechanical and cQED theories. Considering that dopants in silicon are highly competitive qubits, we believe that our optomechanical cQED technology will find important applications in the quantum era.
Control of spontaneously emitted light lies at the heart of quantum optics. It is essential for diverse applications ranging from lasers, light-emitting diodes, solar cells, and quantum information. According to the quantum electrodynamics theory, the spontaneous emission (SE) of an atom can be a weak-coupling radiation process due to the vacuum fluctuations of electromagnetic field. A suitable modification of inhomogeneous environment is required so that the vacuum fluctuations controlling the SE can be manipulated. Inhibiting unwanted SE and boosting desired ones will promote the novel optoelectronic designs tailored to industrial standard. The local density of states (LDOS) counts the number of electromagnetic modes where photons can be emitted at the specific location of the emitter, and can be interpreted as the density of vacuum fluctuations. The inhibition or enhancement of SE boils down to how the LDOS of photons is controlled. In this work, the SE of the excited atoms in 2D arbitrary inhomogeneous environment has been systematically studied. The LDOS determines the radiation dynamics of a point source (for 3D) or a line source (for 2D). In particular, it also determines the SE rate, and the LDOS is represented by the electric dyadic Green’s function. The numerical solution of the electric Green’s tensor has been accurately obtained by the finite-difference frequency-domain method with the proper approximations of the monopole and dipole sources. The SE of the atoms in the photonic crystal and plasmonic metal plates has been comprehensively and comparatively investigated. For both systems, the SE strongly depends on their respective dispersion relations and could be modified or tuned by the finite-structure or finite-size effects. This work is important for the SE engineering and optimized design of optoelectronic devices.
The resonant high-index nanostructures open opportunities for control many optical effects via optically-induced electric and magnetic Mie resonances, mostly localized inside the structures. Especial interest such nanostructures represent for quantum emitters placed inside, that makes possible enhancement of quantum source emission through resonant coupling to localized modes. We have proposed the concept of active dielectric nanoantennas based on nanodiamonds with embedded NV-centers. The study of theoretically dependence of optical properties of this system on the spectral position of the resonant modes has demonstrated that that at some sizes of the diamond spherical particles and certain position of the dipole in the sphere the Purcell factor can achieve the value of 30. We have demonstrated experimentally that the photoluminescence properties of the NV-centers can be controlled via scattering resonances and observed a decrease of the NV-centers lifetime in the studied diamond particles, as compared to nonresonant nanodiamonds. These results are in a good agreement with our theoretical calculations for the average Purcell factor for multiple NV-centers within a nanoparticle. The simplicity of the proposed concept compared to existing photonic cavity systems and applicability for a wide range of color centers in diamond make active diamond nanoantenna an effective tool for creating controllable emitting elements in the visible range for future nanophotonic devices.