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APL Quantum

Dynamic control of super- and subradiance of quantum emitters via near-field photonics and time-varying media

Frank Bello, Saeid Asgarnezhad-Zorgabad, Z. Jalali-Mola, John Francis Donegan, Ortwin G. Hess

Published Mar 1, 2026• 1 citation
Publisher

Abstract

Achieving dynamic and broadband control of superradiance and subradiance at elevated temperatures is central to quantum photonic technologies. Herein, we theoretically investigate near-field photonics combined with adiabatic and non-adiabatic time-varying media—created via temporal modulation of material properties—to dynamically generate and coherently manipulate quantum emission states, including single photons and photon pairs. Distinctively, this cavity-free near-field method operates effectively at practical temperatures (tens of Kelvin), circumventing traditional operational constraints. We initiate this approach by exploiting plasmonically coupled silicon carbide color centers, which are used as quantum emitters (QEs), with relatively long coherence lifetimes, enabling precise quantum state control before temperature-induced dephasing sets in. In particular, a hybrid plasmonic waveguide is used as the light delivery method, where its subdiffracted near-field generates nanoscale heating that effectively tunes the energies of color centers, via phonon occupation, on resonance with the near-field. Furthermore, we employ transparent conducting oxides, such as indium tin oxide, that may achieve significant refractive index modulation on the femto–picosecond timescales. The resulting behavior is that of a photonic time crystal (PTC) or an epsilon-near-zero (ENZ) material response, dependent on modulation times, and characterized by the amplification or increased absorption of light, respectively, where both enhance field localization around the embedded QEs and extend periods of super- or subradiance compared to static conditions. Our methodology significantly simplifies scalable quantum photonic integration, while advancing quantum memories and entanglement capabilities under accessible conditions.

DOI
10.1063/5.0292425

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•Sep 9, 2016•0 citations
Achieving dynamic and broadband control of superradiance and subradiance at elevated temperatures is central to quantum photonic technologies. Herein, we theoretically investigate near-field photonics combined with adiabatic and non-adiabatic time-varying media—created via temporal modulation of material properties—to dynamically generate and coherently manipulate quantum emission states, including single photons and photon pairs. Distinctively, this cavity-free near-field method operates effectively at practical temperatures (tens of Kelvin), circumventing traditional operational constraints. We initiate this approach by exploiting plasmonically coupled silicon carbide color centers, which are used as quantum emitters (QEs), with relatively long coherence lifetimes, enabling precise quantum state control before temperature-induced dephasing sets in. In particular, a hybrid plasmonic waveguide is used as the light delivery method, where its subdiffracted near-field generates nanoscale heating that effectively tunes the energies of color centers, via phonon occupation, on resonance with the near-field. Furthermore, we employ transparent conducting oxides, such as indium tin oxide, that may achieve significant refractive index modulation on the femto–picosecond timescales. The resulting behavior is that of a photonic time crystal (PTC) or an epsilon-near-zero (ENZ) material response, dependent on modulation times, and characterized by the amplification or increased absorption of light, respectively, where both enhance field localization around the embedded QEs and extend periods of super- or subradiance compared to static conditions. Our methodology significantly simplifies scalable quantum photonic integration, while advancing quantum memories and entanglement capabilities under accessible conditions.
Photonic quantum networks frequently demand a consistent and reliable source for generating single photons and entangled photon pairs, which function as quintessential encoders of quantum information. However, many experiments demonstrating quantum algorithms using photons have necessarily been performed at cryogenic temperatures (milli to a few Kelvin), in order to mitigate the adverse effects of temperature dephasing. Encouraged by the relatively long lifetimes of group-N color centers, we show that subdiffracted heating produced by a near-field plasmonic transducer can control the resonant behavior of individual quantum emitters and, consequently, their emission. Our theoretical analysis establishes the ability to control antibunching and superbunching effects at elevated temperatures via highly manipulable, thermally-induced strain fields. Furthermore, our work raises encouraging prospects for the application of color centers in on-chip quantum photonics, while elevating technologies for solid-state quantum information processing towards ever higher temperatures.
Temperature fluctuations in materials used for quantum networks can give rise to lattice vibrations that detune, dephase, and decrease the lifetimes of embedded quantum defects that function as qubits. Most experiments demonstrating quantum operations have been performed at cryogenic temperatures ranging from milli- to a few kelvin, thereby reducing these adverse effects. However, encouraged by the relatively long lifetimes recently discovered for group IV color centers, we aim to show that subdiffracted heating, i.e., nanoscale thermal "hot spots", produced by a plasmonic transducer can control the resonant behavior of individual qubits. Our analysis, reported over largely unexplored physical dimensions for the nanoheating of qubits, establishes the ability to perform dynamic quantum operations at elevated temperatures via thermally mediated control of two-photon coherence and subsequent photon-number entanglement. As such, color centers raise encouraging prospects for advancing on-chip quantum photonics and elevating solid-state quantum information processing technologies toward higher temperatures.
We report theoretical statistics of 1- and 2-qubit (bipartite) systems, namely, photon antibunching and entanglement, of near-field excited quantum emitters. The sub-diffraction focusing of a plasmonic waveguide is shown to generate enough power over a sufficiently small region (<50 × 50 nm 2 ) to strongly drive quantum emitters. This enables ultrafast (10 –14 s) single-photon emission as well as creates entangled states between two emitters when performing a controlled-NOT operation. A comparative analysis of silicon and near-zero index materials demonstrates advantages and uncovers challenges of embedding quantum emitters for single-photon emission and for bipartite entanglement. The use of a movable plasmonic waveguide, in lieu of stationary nanostructures, allows high-speed rasterization between sets of qubits and enables spatially flexible data storage and quantum information processing. Furthermore, the sub-diffraction focusing of the waveguide is shown to achieve cavity-free dynamic entanglement. This greatly reduces fabrication constraints and increases the speed and scalability of nanophotonic quantum devices.
We demonstrate a plasmonic route to control the collective spontaneous emission of two-level quantum emitters. Superradiance and subradiance effects are observed over distances comparable to the operating wavelength inside plasmonic nanochannels. These plasmonic waveguides can provide an effective epsilon-near-zero operation in their cut-off frequency and Fabry-Pérot resonances at higher frequencies. The related plasmonic resonant modes are found to efficiently enhance the constructive (superradiance) or destructive (subradiance) interference between different quantum emitters located inside the waveguides. By increasing the number of emitters located in the elongated plasmonic channel, the superradiance effect is enhanced at the epsilon-near-zero operation, leading to a strong coherent increase in the collective spontaneous emission rate. In addition, the separation distance between neighboring emitters and their emission wavelengths can be changed to dynamically control the collective emission properties of the plasmonic system. It is envisioned that the dynamic modification between quantum superradiant and subradiant modes will find applications in quantum entanglement of qubits, low-threshold nanolasers and efficient sensors.
Abstract Quantum nanophotonics places nanoscale structuring in direct dialogue with photonic quantum information—compressing functionality to the few-nanometre, few-femtosecond frontier while retaining energy efficiency, speed and room-temperature operation. We highlight nanoplasmonic cavity-QED architectures in which extreme mode confinement delivers strong coupling under ambient conditions, enabling ultrafast single-photon emission and near-field multipartite entanglement using industry-grade near-field transducers that nanofocus guided light at practical efficiencies. We set these advances against the arc from early plasmonic cQED proposals and single-emitter Purcell studies to modern time-domain measurements that resolve sub-picosecond polariton/Rabi dynamics—establishing a clear route from concept to device. In parallel, we point to low-loss, high-index Mie resonators whose spectrally sharp electric and magnetic modes afford narrow-band coherent control, filtering and radiation-pattern engineering, and which naturally co-integrate in hybrid metal–dielectric stacks that combine ultrastrong local coupling with low-loss routing and storage. Finally, we discuss quantum nanoplasmonic coherent perfect absorption (qnCPA)—a waveguide-fed, non-perturbing protocol that selectively prepares and protects plasmon–emitter dressed states via dissipation-assisted, unidirectional feeding. Together with macroscopic QED and quantum quasinormal-mode quantization, which regularize open, lossy resonators and clarify when loss can be a resource, these developments chart robust, chip-scale routes to room-temperature quantum technologies.
We demonstrate a plasmonic route to superradiance and subradiance effects over distances comparable to the operating wavelength. Superradiant and subradiant modes are excited by a collection of two-level quantum emitters inside plasmonic nanochannels. These channels can provide an effective epsilon-near-zero operation in their cut-off frequency and Fabry-P\'erot resonances at higher frequencies. The related plasmonic resonant modes are found to efficiently enhance the constructive (superradiance) or destructive (subradiance) interference between different quantum emitters located inside the nanochannels. By increasing the number of emitters located in the elongated plasmonic channel, the superradiance effect is enhanced at the epsilon-near-zero operation, leading to a strong increase in the collective spontaneous emission rate. In addition, the separation distance between neighboring emitters and their emission wavelengths can be changed to dynamically control the collective emission properties of the plasmonic system. It is envisioned that the dynamic modification between quantum superradiant and subradiant modes will find applications in quantum communication and computing systems.