Metasurfaces are ultra-thin structures containing nanoscale patterns that can shape and direct light waves. Most metasurfaces developed thus far are static, meaning their optical properties remain fixed after fabrication and limiting their use in adaptable photonic systems. The EPFL team instead created suspended membranes of crystalline silicon, with the nanostructured layer separated from the surrounding environment by air.

Hatice Altug, who led the work in EPFL’s Bionanophotonic Systems Laboratory within the School of Engineering, said this configuration greatly reduced optical losses that typically limit conventional mid-infrared platforms. Two distinct approaches allowed the researchers to tune the devices without altering their nanostructures. In the electrical approach, integrated electrodes serve as micro-heaters.

Electrical current passing through the electrodes induces changes in the silicon’s optical properties, allowing the metasurface response to be adjusted thousands of times per second. In the optical approach, ultrafast laser pulses induce mobile electrical charges within the silicon, enabling the structures to respond on timescales of billionths of a second, or nanoseconds. The researchers say the combination of high optical performance and rapid tunability could help communication systems transmit information more efficiently and enable sensors that adapt quickly to changing conditions.

Mid-infrared light is relevant to these applications because molecules interact with it in characteristic ways, allowing spectroscopy to identify biological materials, drugs and pollutants. The same light can also carry information in free-space optical communications, where data travel through air rather than through cables or fibers. These potential uses build on the demonstrated tuning performance but remain prospective applications rather than tested clinical or commercial outcomes.

Other proposed directions include compact, low-power devices for free-space optical communications, highly selective and adaptive chemical and biological sensing, and active radiative cooling systems designed to help surfaces release heat in applications such as refrigeration or satellite thermal management. Looking further ahead, the researchers say rapid tunability combined with high optical performance could support advanced photonics applications that require precise control of light, including quantum spectroscopy. The work does not establish performance for any of those individual future systems, but it provides a versatile basis for developing them.

First author Felix Brikh said the platform’s reported optical performance does not come at the expense of scalability because the devices are made using techniques already compatible with large-scale semiconductor production.

Subject of Research: Real-time tuning of suspended crystalline-silicon metasurfaces for mid-infrared photonics

Article Title: A new way to control infrared light in real time

Article References: A new way to control infrared light in real time. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: mid-infrared light, silicon metasurfaces, real-time modulation, nanosecond tuning, optical communications, infrared spectroscopy, photonic sensing, radiative cooling, quantum photonics, EPFL, control, infrared

The system addresses limitations associated with conventional approaches to structured-light generation. Free-space setups commonly rely on spatial light modulators, multi-stage waveplate arrays and polarizers to produce vortex, vector and cylindrical vector beams, but these discrete components can require bulky optical paths, precise alignment and protection against environmental disturbances. Existing on-chip approaches have commonly used single-mode waveguide excitation, which restricts the diversity of output topological charges and can couple spatial wavefronts to polarization degrees of freedom. The researchers designed their chip to separate these functions while retaining a compact silicon-photonics platform.

At the input, a high-fidelity mode-conversion and multiplexing network converts selected higher-order waveguide modes, including TE0 and TE1, into independent coherent channels. Different guided modes have distinct dispersion characteristics, and the design uses this property together with inverse-optimized subwavelength meta-waveguide gratings. The result is simultaneous or selective emission of multimode orbital-angular-momentum beams with varying topological charges from one integrated aperture, expanding the accessible spatial modes beyond the single fundamental-mode output typical of many conventional on-chip generators. The device also integrates a thermo-optic phase-shifter array that independently controls the amplitude and relative phase of outgoing orthogonal components, enabling linear, circular and elliptical polarizations as well as inhomogeneous cylindrical vector fields.

By changing the electrical drive signals, the researchers altered the output Stokes parameters and steered and stabilized the optical states at selected points across multiple Poincaré spheres. They then coherently superimposed fundamental states extracted from different high-order Poincaré spheres to generate representative complex fields in a four-dimensional parameter domain. The demonstrated chip therefore provides programmable generation of high-dimensional structured light in a millimeter-scale silicon platform. The team identified space-division multiplexing communications, reconfigurable quantum photonics and custom topological optical structures, including optical skyrmions, as potential future applications. It also described future co-integration with high-speed modulators, laser sources, detectors and quantum emitters as a route toward a more self-contained structured-light system. The reported result is an experimental demonstration of multidimensional state generation; performance in complete communications, metrology or quantum-information systems was not established in the supplied research description.

Subject of Research: Experimental silicon-photonic control of multidimensional structured light across multiple Poincaré spheres

Article Title: Fully tunable on-chip meta-generator mapping multidimensional Poincaré spheres

Article References: Fully tunable on-chip meta-generator mapping multidimensional Poincaré spheres. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: silicon photonics, structured light, Poincaré spheres, orbital angular momentum, polarization control, meta-waveguides, photonic integrated circuits, thermo-optic tuning, four-dimensional optics, quantum photonics, Fully, tunable

The experiment implements a Hamiltonian with two coupled modes and a detuning that varies across parameters p and q. Its non-symmorphic symmetry identifies H(p, q) with H(−p, q + π), reducing the fundamental domain to a rectangle with an orientation-reversing boundary. That geometry turns the parameter rectangle into a Klein bottle rather than an orientable surface. The nonorientability modifies the global rules governing degeneracies: the usual fermion-doubling constraint becomes a relation between boundary braids, and a phase with a nonzero invariant can remain gapless while hosting exceptional points whose topological charges cannot be removed locally. For the two-band model used here, the relevant braid-group elements reduce to integer winding numbers.

An exceptional point is a non-Hermitian degeneracy in which eigenvalues and their corresponding eigenstates coalesce, reducing the dimensionality of the eigenspace. This differs from a diabolic point in a Hermitian system, where eigenvalues can coincide while the associated eigenstates remain orthogonal. The non-diagonalizable character of exceptional points allows eigenvalues to exchange when a degeneracy is encircled in parameter space. Their winding properties therefore encode how the spectrum changes under continuous parameter variation. In this experiment, that information was read from the orientation of a Fermi arc, defined as the curve in parameter space where the imaginary part of the eigenvalue gap closes.

Non-Hermitian photonic systems commonly obtain their behavior from optical gain and loss, but the researchers used a different strategy for a linear, CMOS-compatible silicon circuit. They first shifted the Hamiltonian so that all eigenvalues lay in the lower half of the complex plane, then embedded the desired non-unitary evolution in a larger unitary operation through auxiliary, or ancilla, modes. The unitary operation coherently redirects energy into those modes, which are excluded from the nominal output, while reproducing the effective differential-loss dynamics in the measured system. The circuit therefore simulated the target Hamiltonian without incorporating a nonlinear gain material or a dedicated optical amplifier.

The experimental platform was an 8-by-8 silicon photonic integrated circuit containing 28 thermally tunable Mach–Zehnder interferometers and 56 heating electrodes. Each interferometer combined multimode interference couplers with internal and external phase shifters, allowing independent control of beam splitting and relative phase. A 1550-nanometer pulsed diode laser supplied coherent light, and a polarization controller selected the transverse electric mode in the waveguides. One optical switch selected among the principal input modes, while a second rapidly scanned the eight output channels so the full intensity distribution could be recorded with a power meter. Calibrated electrical currents controlled the phase shifters, allowing each target transformation to be synthesized on the mesh and reconfigured for different parameter values.

Initial tests covered coupling strengths from 1 to 12 and compared measured intensities in the first two modes with numerical simulations of oscillation and decay. Across five selected combinations of the coupling c and the phase parameters p and q, the study reported weighted correlation coefficients above 0.97. These measurements checked the implementation over a broad range of couplings before the topological analysis focused on c = 1. The demonstrated quantity was a controlled set of optical transformations rather than a direct physical image of the mathematical surface: the Klein-bottle structure arose from the boundary relations imposed on the programmed two-mode Hamiltonians.

To recover the effective non-Hermitian Hamiltonian, the team measured all four complex elements of the two-mode evolution operator at five times: 0.05π, 0.10π, 0.15π, 0.20π and 0.25π. The investigation sampled 11 points along the predicted Fermi arc and eight points in gapped regions. At points on the arc, the two diagonal evolution-matrix elements showed minimal amplitude separation, accompanied by symmetric phase bifurcation. At off-arc points, their amplitudes diverged markedly and the phase bifurcation was asymmetric. Fitting the measured matrix elements across the five times produced an effective generator whose real and imaginary components could be compared with theoretical calculations. The overall reported agreement between experiment and theory for the illustrated reconstruction reached 98.83%, while small nonzero real diagonal terms in one comparison were attributed to residual experimental noise.

The phase diagram itself was computed numerically, with a small perturbation applied to sharpen the visibility of the Fermi arc, and the experiment supplied targeted measurements around that predicted structure. The calculation showed one Fermi arc crossing only the orientation-reversing boundary associated with the p-axis. The arc retained a consistent orientation on either side of that boundary, while the q-axis boundary carried a trivial braid. In the authors’ topological analysis, this meant that the p-direction boundary braid was nontrivial and that the total exceptional-point charge was plus or minus two. The nonzero flow had to be sourced by exceptional points at which a Fermi arc ends or, in a more finely tuned configuration, by a monopole at which several arcs emerge. The measured orientation therefore supported the presence of two same-charge exceptional points, or an exceptional-point monopole, that could not annihilate locally on the Klein bottle.

The result shows that reconfigurable linear photonics can emulate complex non-Hermitian Hamiltonians and probe their exceptional topology without material gain. Each coordinate in the mapped parameter space is generated through calibrated internal and external phase settings, allowing the circuit to be reset for different target evolution operators. The authors distinguish this approach from related demonstrations in stabilized fiber rings, metasurfaces, optical cavities, synthetic dimensions, dual-ring fibers and real-space lattices, where non-Hermitian landscapes are produced by tuning physical degrees of freedom. The present experiment instead embeds a specifically nonorientable model directly in a programmable integrated circuit. The demonstrated result is a classical photonic emulation rather than a quantum implementation, although the authors note that coherently redirecting energy into ancilla modes could support future quantum state-engineering work, including coherent absorption measurement.

Subject of Research: Experimental photonic emulation and mapping of non-Hermitian exceptional topology on a Klein bottle using a programmable silicon circuit.

Article Title: Non-Hermitian exceptional topology on a Klein bottle photonic circuit

Article References: Xu, Z.-S., König, J. L. K., Cataldo, A., Yadgirkar, R., Krishna, G., Deenadayalan, V., Zwiller, V., Preble, S., Bergholtz, E. J., Gao, J., & Elshaari, A. W. (2026). Non-Hermitian exceptional topology on a Klein bottle photonic circuit. Light: Science & Applications, 15(1), Article 390. https://doi.org/10.1038/s41377-026-02516-x

Image Credits: AI Generated

DOI: 10.1038/s41377-026-02516-x

Keywords: non-Hermitian physics, exceptional points, Klein bottle, photonic integrated circuit, Fermi arc, silicon photonics, topological physics, Mach–Zehnder interferometers, quantum photonics, unitary dilation, Non-Hermitian, exceptional

Writing in the journal Light: Science & Applications, the team describes a self-aligned heterogeneous photonic integration method that fuses diamond nanobeams containing quantum emitters with titanium dioxide photonic circuits. The published work, titled Self-Aligned Heterogeneous Quantum Photonic Integration, demonstrates not merely a fabrication trick but a functioning platform: a hybrid optical cavity that boosts light emission from a silicon-vacancy center in diamond, on-chip routing of photons emitted by that center, and initialization and readout of the emitter’s spin state directly through the chip. Together, these demonstrations establish that quantum light can be generated, controlled, and collected within a single integrated architecture.

The central insight behind the method is elegantly simple. Rather than trying to place a tiny diamond structure onto a photonic chip with painstaking external alignment, the researchers guide a diamond nanobeam into a pre-patterned structure where it naturally settles into its correct position. The surrounding photonic device is then fabricated around it. Because alignment is built directly into the fabrication process itself, the approach sidesteps the positioning errors and excess insertion losses that have plagued earlier attempts at heterogeneous quantum photonics. The technique transforms what was once a delicate manual assembly problem into a self-correcting manufacturing step.

“We wanted a practical way to combine high-quality quantum emitters with integrated photonics without paying a large price in optical loss,” said Kinfung Ngan, the first author of the study and a graduate student at JILA and the University of Colorado Boulder. That practical motivation runs through every element of the design. Insertion loss, the fraction of light sacrificed whenever a photon crosses from one optical element into another, is the silent killer of quantum photonic scalability. In quantum systems, every lost photon is an irreplaceable quantum resource, and cascaded losses across many interfaces can render even a sophisticated chip useless for real quantum applications.

The choice of materials reflects a careful balancing act. Diamond hosts some of the most celebrated quantum emitters in solid-state physics, including the silicon-vacancy center used in this work, whose spin states can be initialized, manipulated, and read out with high fidelity. Titanium dioxide, by contrast, is a superb material for low-loss photonic circuits and is compatible with mature fabrication processes. Previous efforts to combine them typically relied on active alignment under microscopes or on transfer techniques that left the two materials imperfectly registered, introducing scattering and reflection at every junction. The self-aligned scheme eliminates that fragile step by letting physics do the positioning.

The demonstrated device functions read like a checklist for quantum photonic technology. The hybrid optical cavity formed around the diamond nanobeam enhances the emission rate of the silicon-vacancy center, a phenomenon rooted in cavity quantum electrodynamics that allows a quantum emitter to funnel its photons preferentially into a well-defined optical mode. Once generated, those photons are routed through the titanium dioxide circuit, showing that the interface between the two materials transmits light efficiently enough to preserve the fragile quantum information it carries. Finally, the team showed that the spin state of the emitter could be initialized and read out through the chip, confirming that the full quantum control loop survives integration.

“By showing enhanced emission, on-chip spin control, and efficient photon routing in the same platform, this work points to a realistic path toward scalable quantum photonic chips,” said Dongyeon Daniel Kang, a corresponding author of the study and a senior research scientist at the Korean Institute of Science and Technology. The significance of combining all three functions on a single device cannot be overstated. Many laboratories have demonstrated individual pieces of this puzzle, such as enhanced emission in one architecture or spin control in another, but assembling them within one coherent, low-loss platform has remained the field’s stubborn bottleneck.

The architecture also leaves room for growth. According to the authors, the same platform is compatible with advanced photonic designs for efficient and broadband photon collection, providing a flexible foundation upon which larger and more complex quantum photonic circuits can be erected. Equally important, the self-aligned integration method is not restricted to diamond and titanium dioxide. The researchers emphasize that the approach could extend to other quantum emitters and photonic materials, opening the door to a general integration strategy rather than a bespoke solution for one material pair. That generality could prove decisive as the community explores alternative color centers, defects, and host crystals with their own advantages.

The broader implications reach into the infrastructure of future quantum technologies. Quantum networks will require quantum repeaters, devices that catch, store, and retransmit entangled photons across continental distances, and those repeaters depend on interfaces that marry long-lived spin memories with efficient optical collection. Large-scale photonic quantum processors, meanwhile, will demand thousands of emitters and routing elements stitched together with minimal loss. “By overcoming a key integration bottleneck, this work opens exciting opportunities for large-scale photonic quantum processors and quantum repeaters,” said Shuo Sun, the corresponding author, a JILA Fellow, and an assistant professor at the University of Colorado Boulder.

What makes this advance resonate beyond the laboratory is its framing as a practical route rather than a proof of principle. By reducing optical loss at the material interface and demonstrating generation, control, and collection of quantum light on chip, the work addresses the central question that has shadowed quantum photonics for years: how to connect the best quantum materials to chip-scale photonic technology in a way that survives the transition from a handful of devices to the vast circuits that quantum computers and networks will require. If the self-aligned philosophy proves as extensible as its creators suggest, the marriage of diamond and titanium dioxide may be remembered as the moment integrated quantum photonics acquired its manufacturing playbook.

Subject of Research: Self-aligned heterogeneous integration of diamond quantum emitters with titanium dioxide photonic circuits for low-loss quantum photonic chips

Article Title: A practical route to low-loss integrated quantum photonic chips

Article References: A practical route to low-loss integrated quantum photonic chips. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: quantum photonics, diamond nanobeams, silicon-vacancy center, titanium dioxide, heterogeneous integration, insertion loss, spin control, optical cavity, quantum repeaters, integrated photonics, photon routing, quantum networks

Vertically emitted integrated light sources radiate from the chip surface at near-normal angles, and that geometry carries real engineering advantages. Because the light leaves the chip perpendicular to its plane, such devices can be packed into dense two-dimensional arrays, their output can be collected with simple free-space optics, and they can serve as convenient bridges between on-chip platforms and external optical systems. These attributes make them attractive for optical communications, optical displays, precision metrology, integrated quantum light sources, and terahertz photonics. Conventional devices of this type, such as vertical-cavity surface-emitting lasers, however, are tied to the gain bandwidths of their constituent materials, which limits the wavelengths they can produce.

The spectral gap that motivated the new work sits near 810 nanometers, a region where vertically emitted integrated light sources remain scarce despite strong demand. Precision atomic, molecular, and optical physics experiments, the quantum technologies that build on them, and laser surgery all rely on light in this part of the spectrum. Filling such gaps is where nonlinear optical frequency converters come in: by mixing existing laser light in a nonlinear crystal, new wavelengths can be generated that no single semiconductor gain medium could reach. The difficulty has been that integrating both a frequency converter and a vertically emitted source on the same chip poses substantial challenges, since the nonlinear process must be phase matched while the output must still escape the chip surface.

To overcome this, the team, led by Professor Ya Cheng of East China Normal University in collaboration with Professor Jintian Lin of the Shanghai Institute of Optics and Fine Mechanics and Associate Professor Jielei Ni of Shenzhen University, introduced a transverse phase matching nonlinear interaction in a counterpropagating configuration. Under continuous-wave excitation from a single pump laser, nearly-degenerate square modes were excited in a thin-film lithium niobate microdisk resonator. Through sum-frequency generation inside the resonator between the pump light and a counterpropagating stimulated Raman lasing signal excited by that same pump, the researchers realized a coherent nonlinear light source with near-vertical emission at 817 nanometers.

The device at the heart of the experiment is an X-cut thin-film lithium niobate microdisk resonator with a diameter of approximately 66 micrometers. Lithium niobate is prized in integrated photonics for its strong second-order nonlinearity and wide transparency window, making it a natural choice for frequency conversion on chip. To shape the resonator’s mode structure, the researchers introduced a weak perturbation by placing an optical tapered fiber in contact with the periphery of the microdisk. This contact broke the rotational symmetry of the original whispering-gallery modes, which normally circulate around the disk rim, and induced the coherent recombination of a quasi-degenerate whispering-gallery-mode sequence into high-Q nearly-degenerate square modes.

Those square modes do two jobs at once. First, they significantly enhance the Rayleigh backscattering of the forward-propagating pump light, which is essential for building up a counterpropagating wave inside the resonator. Second, they provide favorable spatial overlap between the optical fields involved in the nonlinear interaction, strengthening the sum-frequency generation process. The high quality factors of the modes, meaning the photons circulate many times before leaking out, establish the strong intracavity field enhancement on which efficient nonlinear conversion depends. This combination of mode engineering and counterpropagating geometry forms the technical foundation of the demonstration.

The experimental sequence began with continuous-wave pump light at 1555.42 nanometers coupled into the microdisk. Once the pump power exceeded the threshold for stimulated Raman scattering, pronounced stimulated Raman lasing signals centered at 1721.26 nanometers appeared in both the forward and backward propagation directions. The threshold powers were remarkably low, measured at 0.439 milliwatts in the forward direction and 0.427 milliwatts in the backward direction, with slope efficiencies of 32.3 percent and 21.1 percent respectively. The two split resonances of the pump mode exhibited loaded quality factors of 4.48 million and 4.39 million, values that enable the substantial intracavity field enhancement exploited in the subsequent conversion step.

As the pump power was increased further, several nonlinear optical signals emerged in the short-wavelength region of the spectrum. Among them, the signal at 817.06 nanometers was generated through sum-frequency generation between the pump light and the counterpropagating stimulated Raman laser. Crucially, this signal was emitted from the top surface of the microdisk at nearly normal angles, with a conversion efficiency of 0.272 percent per milliwatt of pump power. The emission angle deviated from the normal direction by only approximately plus or minus 6.7 degrees, confirming that the transverse phase matching scheme in the counterpropagating configuration delivers on its promise of near-vertical output from the chip surface.

The significance of the result lies in how it decouples emission wavelength from material gain. Instead of searching for a semiconductor that lases at 810 nanometers, the researchers used a single telecom-band pump laser and the intrinsic nonlinearity of lithium niobate to synthesize the desired wavelength on the same chip. Because the frequency conversion process is governed by phase matching and mode design rather than by a gain bandwidth, the same architecture could in principle be retuned to other target wavelengths by adjusting the resonator geometry and pump frequency. The authors describe the work as establishing a new technical route for extending the spectral coverage of vertically emitted integrated light sources, and as providing a pathway toward integrated coherent light sources, quantum light sources, and free-space optical interfaces.

The demonstration also underscores the growing maturity of thin-film lithium niobate photonics as a platform where high-Q resonators, stimulated Raman scattering, and second-order nonlinear mixing coexist on a single chip smaller than the width of a human hair. For applications in atomic and molecular physics, where lasers near 810 nanometers are workhorses, a chip-scale source that emits nearly vertically could simplify experimental setups and enable dense arrays of independently addressable emitters. For quantum technologies, on-chip nonlinear sources with free-space output offer a direct interface between flying photonic qubits and integrated circuits. While the reported conversion efficiency and output power remain modest compared with bulk laboratory systems, the low Raman thresholds, quality factors in the millions, and near-normal emission angle together mark a convincing proof of principle that nonlinear frequency conversion and vertical emission can be unified on a photonic chip.

Subject of Research: On-chip vertically emitted nonlinear light sources in thin-film lithium niobate microdisk resonators

Article Title: Researchers develop on-chip light source that emits light nearly vertically

Article References: Researchers develop on-chip light source that emits light nearly vertically. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: thin-film lithium niobate, microdisk resonator, stimulated Raman scattering, sum-frequency generation, phase matching, nonlinear optics, integrated photonics, vertical emission, whispering-gallery modes, on-chip light source, quantum photonics, near-infrared laser

The central challenge the researchers set out to solve is a familiar one in nanophotonics. Two-dimensional semiconductors such as WSe2 host tightly bound electron-hole pairs called excitons, which possess large oscillator strengths and make these materials attractive for photodetectors, light emitters, valleytronics, and quantum technologies. Yet because the material is only one atom thick, its overlap with free-space light is vanishingly small. Conventional dielectric resonators, including photonic crystals, microring resonators, and distributed Bragg reflector cavities, confine light only to diffraction-limited volumes, which limits how strongly the cavity field can interact with the monolayer. Plasmonic structures can squeeze light into nanoscale gaps, but the ohmic losses in metals reabsorb photons and degrade the coherence that quantum applications demand.

The Purdue-Harvard collaboration turned to photonic inverse design, specifically adjoint-based topology optimization, to escape this trade-off. In this approach, a computer algorithm iteratively reshapes the distribution of silicon and air within a metasurface unit cell to maximize the electric-field intensity at a target point on the surface. Each optimization cycle consists of a forward electromagnetic simulation, an adjoint simulation driven by a virtual dipole at the target location, and a gradient-based update of a continuous material-density field. Gaussian filtering and a progressively sharpened Heaviside projection push the design toward binary, manufacturable patterns, with roughly 200 to 250 iterations required before the figure of merit saturates. Strikingly, regardless of the random starting point, the algorithm consistently converged on a bowtie-like gap at the center of each unit cell, suggesting that this geometry represents a global optimum for field concentration.

The resulting cavities were fabricated from 100 to 200 nanometer-thick silicon layers on sapphire substrates using electron beam lithography and reactive ion etching. Simulations of the ideal designs predicted local field-intensity enhancements exceeding 50-fold relative to the incident field, with an effective mode volume of approximately 30 by 30 by 100 cubic nanometers, corresponding to roughly one 2500th of a cubic wavelength. The optical hotspots sit directly beneath where the WSe2 monolayer would rest, ensuring deterministic coupling between the excitons and the confined cavity mode. Because the cavities are supported on a substrate rather than suspended as membranes, they are mechanically robust and well suited to the scalable integration of van der Waals materials.

Experimentally, the team transferred large hexagonal boron nitride-encapsulated WSe2 monolayers, roughly 40 by 30 micrometers in area, onto arrays of these cavities using a gold-assisted exfoliation and transfer technique. Each flake was positioned so that part of it lay on the cavity array and part on adjacent unpatterned silicon, enabling a direct on-chip comparison between cavity-coupled and reference emission. Raman spectroscopy confirmed that strain induced by the underlying pattern was negligible, with peak shifts below one wavenumber. Photoluminescence maps then revealed bright, reproducible emission from the cavity regions: raw enhancements of approximately 6-fold, 14-fold, and, for the best-performing array, nearly 28-fold were measured across three different cavity designs, with a consistent average of about tenfold. When normalized to the tiny effective hotspot area, this corresponds to a per-area enhancement on the order of one thousand.

Numerical simulations that incorporated realistic material absorption and the actual shapes extracted from scanning electron microscope images helped explain why the measured enhancement fell short of the ideal 50-fold prediction. The small feature sizes and dense patterning amplify proximity effects during electron beam lithography, and etching introduces roughness that scatters light and degrades field localization. Loading the cavity with the WSe2 and boron nitride stack further broadens and shifts the resonance. When all of these imperfections were included, the simulated near-field enhancement dropped to approximately tenfold, in close agreement with the experimental photoluminescence results and the observed lifetime shortening. The simulations also showed that emitters placed in the hotspot radiate highly directional light, with much of the power falling within the collection cone of a standard high-numerical-aperture microscope objective, whereas emitters on flat silicon radiate mostly at grazing angles.

Perhaps the most intriguing findings came from time-resolved photoluminescence measurements. Using femtosecond pulsed excitation, the researchers found that exciton decay on the cavities became strongly non-exponential at all pump powers, while decay on the flat reference regions remained nearly exponential except at the highest powers. Fitting the decay curves with a mixed model combining a stretched exponential and a single exponential revealed a stretching parameter of roughly 0.38 on the cavity, very close to the value of one third expected for two-dimensional dipole-dipole energy transfer between excitons. Off the cavity, the stretching parameter started near 0.8 at low power and decreased as excitation increased. The team also measured an approximately eightfold shortening of the exciton lifetime on the cavity, consistent with Purcell-enhanced radiative decay.

The power dependence of the decay dynamics pointed to cavity-mediated exciton-exciton interactions as a dominant mechanism. A biexcitonic recombination model best described the shortening of the effective decay time with pump power, and the extracted biexcitonic recombination coefficient on the cavity was more than an order of magnitude, about 33 times, larger than off the cavity. By concentrating optical near fields into nanoscale hotspots, the cavities increase the local exciton density and strengthen resonant dipole-dipole interactions, effectively amplifying many-body excitonic phenomena that are normally difficult to access. Saturation measurements reinforced this picture: emission on the cavity saturated at 20 microwatts of pump power, five times lower than the 100 microwatts required off the cavity, indicating substantially enhanced excitonic nonlinearities.

Low-temperature spectroscopy added further richness. Between 5 and 200 kelvin, the cavity-coupled monolayers displayed a well-resolved manifold of excitonic states, including bright excitons, trions, biexcitons, and defect-bound excitons, with noticeably narrower linewidths on the cavity than on the flat substrate. The presence of trions, which normally require deliberate gate-controlled doping, revealed unintentional electron doping introduced during the gold-assisted transfer, at densities estimated between ten to the eleventh and ten to the twelfth per square centimeter. Notably, defect-bound exciton emission, which persisted even to room temperature, exhibited unexpectedly short lifetimes on the cavity, roughly half those of the bright excitons, and about twice shorter on the cavity than off it at every detection wavelength.

The researchers emphasize that the reported raw enhancement values are the most physically meaningful metric for practical applications, even though normalized figures are conventionally used to compare across studies. Compared against previously reported plasmonic enhancements of WSe2 emission, the dielectric platform is competitive while preserving coherence and enabling efficient light extraction. The work establishes topology-optimized silicon-on-sapphire cavities as a versatile, CMOS-compatible alternative to plasmonics for controlling exciton-photon and exciton-exciton interactions, and the authors anticipate that the platform will accelerate the integration of van der Waals semiconductors into scalable quantum photonics, opening routes toward cavity-enabled quantum many-body physics, valley-selective emission, and unprecedented excitonic nonlinearities, with a detailed study of enhanced two-photon nonlinearities planned as a follow-up.

Subject of Research: Topology-optimized dielectric nanocavities enhancing excitonic light emission and exciton-exciton interactions in monolayer WSe2

Article Title: Topology-optimized dielectric cavities for enhanced excitonic light emission from WSe2

Article References: Matthiessen, O., Triplett, B., Yesilyurt, O., Cassara, D., Pagadala, K., Yang, M. M., Llacsahuanga Allcca, A. E., Ather, H., Fruhling, C., Solanki, A. B., Chen, Y. P., Alaeian, H., Kildishev, A. V., Shalaev, V. M., Capasso, F., Boltasseva, A., & Mkhitaryan, V. (2026). Topology-optimized dielectric cavities for enhanced excitonic light emission from WSe2. Light: Science & Applications, 15(1), Article 387. https://doi.org/10.1038/s41377-026-02436-w

Image Credits: AI Generated

DOI: 10.1038/s41377-026-02436-w

Keywords: WSe2, topology optimization, dielectric cavities, nanophotonics, excitons, photoluminescence, Purcell enhancement, two-dimensional semiconductors, inverse design, quantum photonics, silicon photonics, light-matter coupling

Skyrmions were originally conceived by Tony Skyrme in the 1960s as solitonic solutions of nonlinear field theories, particle-like knots in a continuous field whose identity is fixed by an integer topological charge. In magnetic materials, ultracold atomic gases, liquid crystals and even acoustic systems, these whirls of spin have been studied intensively because their topology protects them against small perturbations, making them attractive carriers of information. In optics, skyrmions have been built from the interplay of polarisation and spatial structure, with the Stokes parameters of a paraxial beam mapping the transverse plane onto the Poincaré sphere. What remained elusive was a quantum version in which the topology itself is not merely a static property of a prepared state but a dynamic, remotely addressable feature of an entangled system.

The new experiment begins with a deceptively simple quantum state. Photon A carries only polarisation, existing in a superposition of right- and left-circular states, while photon B carries one of two possible skyrmion states, each a non-separable combination of the photon’s polarisation and its orbital angular momentum, the twisted spatial structure described by Laguerre-Gaussian modes. Crucially, photon B on its own is described by a mixture of these skyrmion states, so no well-defined spin texture or skyrmion number exists until a measurement is made on photon A. Only when the polarisation of the partner photon is projected does the topology of photon B crystallise into a definite skyrmion with a definite topological number. The researchers describe this arrangement as a non-local quantum dial for topological structure.

To map this dial, the team introduced a conceptual tool they call the topological Bloch sphere. Whereas a conventional Bloch sphere parametrises the states of a two-level quantum system, this new sphere has basis vectors that are themselves topological states, so every point on the sphere corresponds to a different superposition of the two skyrmion states and therefore to a different Bell state, carrying its own skyrmion number. At the poles of the sphere, where the projections select the basis states, the polarisation texture forms a higher-order skyrmion. Along the equator, where the two basis states are combined in superposition, the texture breaks apart into multiple localised quasiparticles, each with its own skyrmion number, whose individual contributions sum to the total wrapping number of the field.

Experimentally, the photons were generated by spontaneous parametric downconversion in a nonlinear crystal, producing pairs entangled in orbital angular momentum at two different wavelengths, 1550 nanometres and 810 nanometres, separated by a dichroic mirror. Electrically tunable q-plates, liquid-crystal devices with azimuthally varying optical axes, then transformed the orbital-angular-momentum-entangled state into the desired spin-skyrmion entangled tripartite state, with the q-plate charge tailoring the accessible skyrmion sectors. Spatial light modulators, waveplates and single-mode fibres coupled to avalanche photodiodes completed the apparatus, with coincidences recorded within a half-nanosecond window.

The verification was rigorous. A violation of the Clauser-Horne-Shimony-Holt Bell inequality confirmed the non-local character of the correlations, with Bell parameters of 2.53 plus or minus 0.005 and 2.47 plus or minus 0.004 for the two heralded states, both beyond the classical bound of two. A full quantum state tomography, comprising six polarisation projections on the heralding photon and twenty-one combined measurements on the skyrmion photon, reconstructed the density matrix with a fidelity of 0.93 and a purity of 0.96. From the reconstructed state the team extracted the spatially varying Stokes parameters and computed the skyrmion number directly, observing the expected switching between topological sectors: for one configuration the number moved between approximately minus two at the poles and minus four at the equator, and for a second, generated with higher-charge q-plates, between approximately minus three and minus six, in each case matching theory to within a few percent.

The most visually striking outcome is the dynamics. By continuously varying the amplitude and phase angles of the polarisation projection on photon A, the researchers watched the localised quasiparticles of photon B’s multiskyrmion move. Changing the amplitude angle drove the quasiparticles radially, drawing them in from infinity toward the central distribution as the angle increased, until near the pole of the sphere they merged with the central skyrmion and could no longer be resolved as separate objects. Changing the phase angle instead set the quasiparticles orbiting around the centre, while each also exhibited a local spin arising from the precession of its Stokes vector. The symmetry of the distribution governed the total angles traversed: the two-quasiparticle configuration completed one orbit and one spin rotation per full phase scan, while the threefold-symmetric configuration completed an orbit of two-thirds of a full turn and a spin of four-thirds of a turn.

Beneath the spectacle lies a deeper point about multipartite entanglement. By constraining photon B to two of its three spatial modes, the team isolated an embedded GHZ-like state, the tripartite analogue of a Bell pair, in which the polarisation of photon A, the polarisation of photon B and one orbital angular momentum mode of photon B form the familiar pattern of a GHZ state. Projecting photon A onto its basis states collapses the remainder into separable states with trivial topology, while superposition projections collapse it into Bell states encoded in the spin and orbital angular momentum of photon B, each visible as a distinct skyrmionic texture with the same skyrmion number but a different spatial pattern. The Bell-state structure of the embedded GHZ state thus becomes something one can literally see in the polarisation field of a single photon.

The implications stretch toward quantum technology. Because the evolving skyrmionic structure of one photon can serve as a probe of its entangled partner, any perturbation acting on the partner can be read out as a transition between topological sectors or as a subtle shift in the quasiparticle dynamics, suggesting a route to quantum sensing in which complex channel features are mapped onto robust topological observables. The non-degenerate, dual-wavelength implementation adds versatility, allowing topological control at one technologically convenient wavelength while the topology is used or detected at another, with prospects including nonlinear quantum transport and the remote transfer of skyrmionic topology to matter. The authors also envision sharing such states across quantum networks, granting a resource-scarce partner access to complex topological structures that would otherwise be beyond their experimental reach, and exploiting the multipartite state complexity for multi-level quantum communication encoding.

What began six decades ago as an abstract field-theoretic construction has now become a controllable, moving, quantum-mechanical object of light, steered from afar by nothing more than the choice of measurement made on a distant entangled photon. In turning the topology of light into a remote-controlled dial, the researchers have not only made entanglement visible in an entirely new way but have opened a laboratory in which the particle-like textures of quantum fields can be engineered, animated and ultimately put to work.

Subject of Research: Remote control of quantum skyrmion topologies in entangled photon states to visualise tripartite entanglement dynamics

Article Title: Remote engineering of particle-like topologies to visualise entanglement dynamics

Article References: Nothlawala, F., Sephton, B., Ornelas, P., Koni, M., Piccirillo, B., Feng, L., Nape, I., D’Ambrosio, V., & Forbes, A. (2026). Remote engineering of particle-like topologies to visualise entanglement dynamics. Light: Science & Applications, 15(1), Article 368. https://doi.org/10.1038/s41377-026-02443-x

Image Credits: AI Generated

DOI: 10.1038/s41377-026-02443-x

Keywords: skyrmions, quantum entanglement, quantum photonics, orbital angular momentum, topological Bloch sphere, GHZ states, Bell inequality, structured light, quantum state tomography, q-plates, quantum sensing, multiskyrmions

The review, authored by Hooman Barati Sedeh and Natalia M. Litchinitser of the Department of Electrical and Computer Engineering at Duke University, was made available online on May 18, 2026 and appears in Volume 18, Issue 04 of the IEEE Photonics Journal on August 1, 2026. Its central subject is a paradigm the authors describe as nonlinear topology imprinting, in which the spatial topology of an optical field at its fundamental frequency is directly transferred to the harmonic radiation generated within a metasurface. In other words, rather than fabricating a new optical element for every desired wavelength and pattern, the structure of the input beam is faithfully copied onto newly generated frequencies by the nonlinear response of the material itself. The work was also featured in the journal’s Special Issue on Photonics for Climate Change Mitigation and Adaptation, a nod to the growing relevance of energy-efficient photonic technologies in addressing global environmental challenges.

To appreciate why this matters, it helps to consider the physics of nonlinear frequency conversion. When intense light propagates through a medium with a nonlinear polarization response, new frequencies are born: second-harmonic, third-harmonic, and sum- or difference-frequency radiation, among others. In bulk nonlinear crystals, this process has been exploited for decades, but the wavefront of the generated light is typically dictated by phase-matching conditions and the geometry of the crystal, leaving limited freedom to impose arbitrary spatial structure. Metasurfaces change the calculus entirely. These are planar arrays of subwavelength resonators, often made of dielectric materials, each engineered to impart a precise amplitude, phase, and polarization response to incident light. By patterning the resonators across the surface, researchers can effectively program the wavefront of light at the nanoscale, compressing what once required a tabletop of optics into a film thinner than a wavelength.

The difficulty, as the review makes clear, has been combining two jobs at once. A metasurface designed to generate structured light at a harmonic frequency must simultaneously support efficient nonlinear conversion and impose the desired spatial pattern on the output. Designing resonators that operate efficiently at both the fundamental and harmonic frequencies is a formidable constraint, and material absorption at the generated wavelengths can bleed away precious conversion efficiency before the light ever exits the device. Nanofabrication tolerances add further limits, since the smallest features of the resonators must be rendered with high fidelity to preserve the delicate phase profiles that define structured beams. Topology imprinting offers an elegant way around these constraints: instead of encoding the full wavefront into the metasurface geometry, the approach lets the topology of the input field do the work, with the nonlinear process naturally carrying that topology across to the new frequency.

The experimental record reviewed by the authors demonstrates that this is more than theory. All-dielectric metasurfaces composed of subwavelength resonators have been used to realize topology imprinting in the laboratory, generating and preserving a variety of structured optical fields. Among the most striking demonstrations is the third-harmonic generation of optical vortex beams that retain the spatial topology of the fundamental beam. Vortex beams possess a phase singularity at their core, a point of darkness around which the phase winds, and they carry orbital angular momentum that can be used to encode information or exert torques on microscopic particles. Preserving that winding number through a frequency conversion process is notoriously difficult with conventional optics, because the harmonic generation tends to scramble or multiply the topological charge in uncontrolled ways. Topology imprinting sidesteps the problem by design, ensuring the generated harmonic radiation inherits the structure of its parent field.

Even more ambitiously, the review highlights experiments involving optical Hopf links, structured fields in which the lines of polarization or phase are knotted and linked like elements of mathematical topology. That such configurations can be generated and preserved through nonlinear conversion in an ultrathin metasurface underscores the power of the approach: the topological character of light, once considered fragile and difficult to control, becomes a transferable property that survives the birth of new frequencies. This opens the possibility of building frequency-multiplexed structured-light systems, in which the same topological information is carried simultaneously at multiple wavelengths, each generated within a single flat optical element.

The implications stretch across several domains of photonics. In optical communications, structured light offers an additional degree of freedom for multiplexing, potentially increasing the information capacity of free-space and fiber links by encoding data in the spatial structure of beams rather than only in their intensity or wavelength. In holography, metasurfaces that imprint topology across frequencies could produce compact, wavelength-agile holographic displays and projectors. In quantum photonics, preserving the structure of entangled photons through nonlinear processes is essential for building quantum networks that exploit high-dimensional spatial modes, and topology imprinting provides a natural mechanism for achieving that preservation. Advanced imaging systems, meanwhile, stand to benefit from structured illumination patterns that can be generated at multiple wavelengths without swapping optical components. As Dr. Litchinitser notes, nonlinear topology imprinting can pave the way toward compact photonic platforms capable of generating complex structured light fields, with impact across holography, optical communications, quantum photonics, and advanced imaging.

None of this is to say the field is without obstacles, and the review is candid about them. The efficiency of nonlinear frequency conversion in ultrathin metasurfaces remains relatively low, a consequence of the short interaction length: light passes through a film only a few hundred nanometers thick, leaving little distance over which the nonlinear polarization can accumulate. The palette of available nonlinear materials imposes further limits, since many high-performance nonlinear crystals are difficult to integrate into nanoscale resonator geometries, and some promising materials suffer from absorption or damage at the relevant intensities. Scaling these devices and integrating them into on-chip photonic platforms presents its own engineering challenges, from thermal management to coupling efficiency between the metasurface and surrounding waveguides. These are the kinds of problems that will determine whether topology imprinting remains a laboratory curiosity or matures into a commercial technology.

The authors chart several promising paths forward. The development of low-loss, highly nonlinear materials tailored for metasurface integration could dramatically raise conversion efficiencies, and the incorporation of active and tunable functionalities, such as electro-optic or thermo-optic control, would allow a single device to switch between different structured-light outputs in real time. Machine learning is identified as another key direction: inverse-design algorithms trained on electromagnetic simulations can explore resonator geometries far beyond human intuition, optimizing devices for simultaneous efficiency, bandwidth, and topological fidelity. Combined with steady advances in nanofabrication, these tools could shrink the gap between the theoretical promise of topology imprinting and the practical demands of deployed photonic systems.

Taken together, the review positions topology imprinting as one of the more consequential ideas to emerge in nonlinear wavefront engineering in recent years. By treating the topology of light not as a fixed property of a particular beam but as a transferable imprint that survives frequency conversion, the concept unifies two previously separate goals: efficient nonlinear generation and precise spatial control. The result is a vision of photonic hardware in which complex, topologically rich light fields can be produced at multiple wavelengths by flat, compact devices no thicker than a human hair. If the materials and integration challenges identified by the Duke team can be overcome, the technology could find its way into everything from high-capacity communication links and quantum processors to climate-relevant sensing and imaging systems, fulfilling the promise that structured light has held since its earliest demonstrations.

Subject of Research: Topology imprinting in nonlinear metasurfaces for generating and preserving structured light across frequencies

Article Title: IEEE study explores new photonics breakthrough: topology imprinting in nonlinear metasurfaces

Article References: IEEE study explores new photonics breakthrough: topology imprinting in nonlinear metasurfaces. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: nonlinear optics, metasurfaces, structured light, topology imprinting, harmonic generation, optical vortices, orbital angular momentum, photonics, nanophotonics, quantum photonics, holography, IEEE Photonics Journal

The work, carried out by Abhishek Kumar Pandey, Deepak Jain, and Catherine Baskiotis, exploits spontaneous four-wave mixing, a nonlinear optical process in which two pump photons at the same frequency are annihilated to create a correlated pair of photons at two very different frequencies. Energy conservation forces the sum of the two new frequencies to equal twice the pump frequency, while momentum conservation, known as the phase-matching condition, dictates which frequency combinations can actually occur. In a waveguide, the phase-matching condition can be engineered by shaping the geometry of the silicon core, allowing the generated signal and idler photons to be tuned with remarkable precision across a wide spectral range.

What makes the new designs remarkable is the sheer distance between the two photons. The flagship design, targeted at atmospheric quantum key distribution, produces a signal photon at 3.905 micrometres, deep inside a mid-infrared atmospheric transparency window, while its idler partner lands at 1.541 micrometres in the telecom C-band. That separation of roughly 2,364 nanometres is dramatically larger than the record of about 1,125 nanometres theoretically reported in earlier all-solid silicon waveguide studies. Crucially, the design achieves this in the true quantum regime, where at most one photon pair is produced per pump pulse, rather than relying on the high pump powers used in classical demonstrations.

This distinction matters. Previous experiments with air-clad silicon waveguides demonstrated large signal-idler separations of about 2,058 nanometres, but only by using pump peak powers around 20 watts to achieve phase matching. In the quantum regime, pump power must be kept low to suppress multi-pair emission, and with those earlier designs the phase-matched separation collapsed to 1,780 nanometres, placing the mid-infrared photon outside any atmospheric transmission window. The new all-solid designs sidestep this problem by building the phase matching into the waveguide geometry itself, so that it holds even at the milliwatt pump levels required for single-pair emission.

The choice of an all-solid, fully oxide-clad structure is itself strategic. Air-clad waveguides suffer from significant scattering losses caused by sidewall roughness, because the optical mode interacts strongly with the etched surfaces. By surrounding the silicon core with fused silica cladding and a buried oxide layer, the proposed waveguides reduce the modal overlap with etched sidewalls, mitigating fabrication-induced scattering. The team’s calculations show that even at the longest signal wavelength, where silica is nominally opaque, the majority of the optical power remains confined to the silicon core, keeping total material attenuation over the 2-centimetre waveguide to acceptable levels.

To give their predictions quantitative teeth, the researchers adopted a model for the probability of photon-pair generation per pulse and validated it against published experimental data from photon-pair generation in photonic crystal fibre. By modelling the fibre as a simple step-index structure and feeding in the experimental parameters, they computed photon-pair rates that closely matched the measured values across a range of pump powers, outperforming the original theoretical treatment of those experiments. Because the model takes as inputs only the modal properties, the nonlinear index, and the operating conditions, the authors argue that the validation is generic and applies equally to the silicon waveguide geometries, whose modal fields they computed independently using full-vectorial finite element simulations.

Each of the three proposed waveguides is tailored to a specific application. Two designs generate signal photons at 3.265 and 3.461 micrometres, which coincide with absorption bands of methane and nitrogen dioxide respectively, the fingerprint region where these gases reveal their presence. Paired with telecom-band idlers, these sources could power schemes for sensing with undetected light, in which the mid-infrared photon probes the gas while only the telecom photon is ever detected, allowing the entire measurement to be performed with cheap, mature silicon-compatible detectors. The third design, optimised for atmospheric quantum key distribution, places the signal photon at 3.905 micrometres, where atmospheric transmission is dramatically better than at the 1.55-micrometre wavelength used in current daylight quantum communication experiments.

The shift to the mid-infrared could be transformative for free-space quantum communication. At 3 to 4 micrometres, the atmosphere exhibits reduced Rayleigh scattering, lower solar background noise, and greater resistance to weather-related variations, all of which translate into more reliable quantum links and an improved ability to operate in daylight. Shrinking the photon-pair source onto a chip also addresses a critical constraint for satellite payloads, where every gram of mass and cubic centimetre of volume counts. Silicon-on-insulator fabrication is cheap, scalable, and compatible with existing CMOS foundries, making the prospect of flight-qualified quantum sources considerably more realistic than with bulk nonlinear crystals.

The team also addressed the practical obstacles that have plagued mid-infrared quantum optics in silicon. Spontaneous Raman scattering, which can contaminate photon-pair spectra, is predicted to be negligible because the generated photons lie more than 330 Raman linewidths away from the silicon Raman gain peak, placing the Raman gain at the signal frequencies at the level of one part in a million. Two-photon absorption, the bane of silicon nonlinear optics at telecom wavelengths, falls off sharply for pump wavelengths above 1.9 micrometres, and the chosen pump wavelengths between 2.1 and 2.21 micrometres sit in a sweet spot combining strong Kerr nonlinearity with suppressed carrier generation. Numerical tolerance studies further showed that small fabrication imperfections of plus or minus 10 nanometres in the core dimensions cause only slight wavelength drifts that can be compensated by tuning the pump laser.

The predicted operating points are within reach of existing technology. Each design targets a probability of photon-pair generation per pulse of about 0.05, a value considered a practical compromise between source brightness and multi-pair suppression, and achieves this with peak pump powers between 9.2 and 32.2 milliwatts from 5-picosecond pulses. Such pump powers are already delivered by mature thulium and holmium-doped solid-state lasers around 2 micrometres, while integrated 2-micrometre laser sources continue to advance toward the required output levels. With mid-infrared single-photon detectors, including superconducting nanowire devices and frequency-upconversion schemes, progressing rapidly, the authors argue that their chip-scale sources could soon move from simulation to experiment, opening a path toward quantum communication and sensing that spans from the fingerprint region of the molecules to the heart of the telecom infrastructure.

Subject of Research: Silicon waveguide design for quantum-correlated photon-pair generation bridging mid-infrared and telecom bands via spontaneous four-wave mixing

Article Title: Quantitative study of silicon waveguides for the generation of quantum correlated photon pairs bridging mid-infrared and telecom bands

Article References: Pandey, A. K., Jain, D., & Baskiotis, C. (2026). Quantitative study of silicon waveguides for the generation of quantum correlated photon pairs bridging mid-infrared and telecom bands. Results in Optics, 25, Article 101158. https://doi.org/10.1016/j.rio.2026.101158

Image Credits: AI Generated

DOI: 10.1016/j.rio.2026.101158

Keywords: silicon photonics, quantum optics, photon pairs, four-wave mixing, mid-infrared, telecom C-band, quantum key distribution, gas sensing, silicon-on-insulator, phase matching, Raman scattering, integrated photonics

The launch addresses a growing divide in quantum publishing. Much of the existing literature focuses on fundamental theory, mathematical models, or highly controlled demonstrations of quantum behavior. While this work remains essential, many researchers are now confronting a different set of challenges: how to manufacture quantum devices reliably, preserve delicate quantum states, integrate optical components, reduce system noise, and operate complex platforms outside specialized research environments. AQP is positioning itself as a venue for studies that examine these practical questions alongside the underlying science, creating a bridge between quantum physics and deployable technology.

Quantum photonics uses individual particles of light, or photons, to generate, transmit, process, and measure quantum information. Unlike classical optical signals, quantum states can encode information through properties such as polarization, phase, arrival time, and path. Photons can also exhibit entanglement, a uniquely quantum correlation that links measurement outcomes even when particles are separated. These characteristics make photonic systems promising for secure communications, precision sensing, quantum computing, and the exchange of information between quantum processors. Yet the same states that give quantum systems their power are often extremely fragile, making the transition from proof-of-concept experiments to stable devices a demanding engineering task.

AQP is seeking contributions that show how quantum research can function in real technological settings. The journal will welcome work involving quantum materials, optical sources, detectors, components, architectures, and complete systems, particularly when studies explain the path from experimental result to implementation. Researchers are encouraged to describe technological context, identify engineering limitations, and discuss the applications their work could ultimately support. Such details may include the efficiency and stability of a photon source, the performance of a single-photon detector, the losses introduced by an optical circuit, or the methods used to control and measure a quantum device with high precision.

The emphasis on implementation reflects the rapid expansion of the quantum technology sector. Quantum communication platforms are being developed to distribute information through quantum states of light, while quantum sensors are being explored for applications ranging from navigation and medical imaging to geological surveys and environmental monitoring. Photonic approaches are also being investigated for quantum computing, where optical elements can generate and manipulate quantum states. In each case, progress depends not only on demonstrating a quantum effect but also on solving practical problems involving fabrication, packaging, calibration, scalability, energy consumption, and compatibility with existing telecommunications or computing infrastructure.

“ We are thrilled to invite the global research community to share their most groundbreaking discoveries in Advanced Quantum Photonics,” said Uriel Levy, the journal’s editor-in-chief. He described the publication as a dedicated platform for work emerging as quantum technologies move from foundational physics toward practical applications. According to Levy, optics and photonics are central to this transition because they provide the tools used to create, control, transmit, and detect quantum states. He also emphasized that SPIE’s peer-review process, international reach, and publishing infrastructure are intended to give authors broad visibility while maintaining rigorous scientific evaluation.

The journal’s scope is also designed to bring different communities into closer contact. Quantum research increasingly involves physicists, optical engineers, materials scientists, computer scientists, electrical engineers, manufacturers, and technology developers. An academic group may develop a new material for producing single photons, while an industrial team may be focused on integrating that material into a compact device. By encouraging contributions from industry as well as universities and national laboratories, AQP aims to highlight the full chain of development, from materials and components to demonstrations that operate under realistic conditions. Each issue is expected to include contributions from the quantum industry, including implementation and application demonstrations.

SPIE’s decision to establish the journal follows the society’s expanding involvement in quantum science and technology. The organization has added Quantum West to the Photonics West program and has also developed Quantum Catalyst, extending its conference activities into a field that is attracting major scientific and commercial investment. These initiatives provide researchers with opportunities to present emerging work, exchange technical knowledge, and build collaborations. AQP is intended to offer a natural publication route for research presented at such events, particularly studies whose focus is practical development rather than purely theoretical analysis.

The journal will also consider proposals for review articles and perspectives that evaluate progress across quantum materials, components, and systems. These contributions are expected to examine not only advances but also limitations, unresolved technical barriers, and opportunities for future research. That perspective could be especially valuable in a field where impressive demonstrations can sometimes obscure the difficulty of achieving repeatable performance at scale. Clear assessments of reliability, error sources, manufacturing constraints, and application requirements may help researchers distinguish between promising laboratory results and technologies ready for wider adoption.

For authors, SPIE is offering open-access publication at no cost during the journal’s first two years, a policy intended to increase the visibility and international circulation of accepted research. Open access allows readers to consult published studies without a subscription, potentially enabling faster exchange among academic groups, companies, policymakers, and the broader public. Manuscripts can be submitted through the SPIE Digital Library, which hosts the society’s journals, conference proceedings, and books. With quantum technologies developing across national and disciplinary boundaries, the new publication is seeking to become a central forum for research that explains not only what quantum devices can do, but also how they can be engineered to work in the real world.

Subject of Research: Applied quantum photonics, including quantum materials, components, systems, implementation challenges, and practical applications.

Article Title: SPIE Opens Submissions for Advanced Quantum Photonics, a New Journal for Applied Quantum Research

News Publication Date: 13 August 2026

Web References: SPIE; Advanced Quantum Photonics; Quantum West; Quantum Catalyst

References: SPIE announcement concerning the launch and submission opening of Advanced Quantum Photonics.

Image Credits: SPIE

Keywords

Quantum photonics, quantum technology, photonics, quantum computing, quantum communication, quantum sensing, quantum materials, optical engineering, SPIE, peer-reviewed journals, open access, applied physics