Nitride-based micro-LEDs are poised to revolutionize next-generation displays with exceptional brightness and contrast, but their efficiency collapses at the micrometre scale owing to etching-induced sidewall damage, a critical bottleneck hindering commercialization. Here we introduce an in situ dry repair and passivation (IDRP) technique that effectively eliminates plasma-induced sidewall damage, unlocking the full potential of micro-scale devices. This approach not only substantially overcomes the size-related efficiency degradation but also enables a reversed size effect, where efficiency increases as dimensions shrink, even down to 1.6 μm devices. The IDRP-treated devices also exhibit substantially improved manufacturing yield and electrostatic discharge robustness. The IDRP strategy proves universally effective across the nitride-based spectrum, leading to record-high peak external quantum efficiencies of 64.7% and 55.1% for 2 μm blue and green InGaN micro-LEDs, respectively. These unprecedented performance metrics enable high-performance pixels, demonstrated here in a nitride microdisplay tailored for emerging augmented reality and virtual reality applications. As a fully integrated, semiconductor-standard dry process, IDRP provides a simple, rapid and powerful route to advance the industrialization of micro-LEDs, representing a transformative technology for large-scale display manufacturing. An in situ dry repair and passivation technique is developed to overcome plasma-induced sidewall damage in nitride-based micro-light-emitting diodes (micro-LEDs), leading to external quantum efficiencies of 64.7% and 55.1% for 2-μm-sized blue and green micro-LEDs, respectively.
Metal halide perovskite semiconductors are becoming promising candidates for X-ray photon-counting detectors due to their combination of strong stopping power, excellent electronic properties and low cost. However, a key challenge for semiconductor photon-counting computed tomography detectors is that existing response speeds are insufficient to count high-flux X-ray photons at a rate of 3 × 106–1 × 108 photons per second per square millimetre (s−1 mm−2) in common computed tomography scanning. Here we report a combination of edge-on device configuration and chloride alloying to increase the response speed of perovskite photon-counting detectors. The edge-on configuration shortens the charge collection distance by 15 times while maintaining the X-ray absorption, reducing charge transit time by 225 times. Surprisingly, we find that free charges generated by nearly every incident X-ray photon encounter shallow traps in formamidinium lead bromide (FAPbBr3) crystal devices. Chloride alloying of FAPbBr3 crystals dramatically reduces shallow trap density, increasing detector response speed. The high electric field in the edge-on detectors enables complete extraction of charges even if they are trapped by shallow defects. The resulting perovskite detectors show a response time of 37 ns after deconvolution. The edge-on detectors with a pixel size of 200 × 200 µm2 can count 120-kVp X-ray photons, with a high flux of 2 × 108 photons s−1 mm−2, enabling the application of perovskite photon-counting detectors for photon-counting computed tomography and many other applications. The researchers use an edge-on device configuration and chloride alloying to increase the response speed of perovskite photon-counting detectors. A response time of 37 ns is achieved, and detectors with a pixel size of 200 × 200 µm2 can count 120-kVp X-ray photons at a high flux of 2 × 108 photons s−1 mm−2.
Atomic-spin-based comagnetometers are powerful tools for precision sensing and tests of fundamental physics. Compared with the widely used gas-cell comagnetometer systems, cold-atom systems offer access to much shorter distance scales and allow the implementation of optical quantum control techniques. However, to realize long spin coherence times with cold atoms, it is necessary to use diamagnetic atoms and overcome decoherence induced by light shifts. Here we demonstrate a cold-atom comagnetometer based on the nuclear spins of 171Yb (spin-1/2) and 173Yb (spin-5/2), jointly trapped in an optical lattice. Vector light shifts are suppressed by enforcing linear polarization of the lattice, whereas tensor shifts in 173Yb are suppressed via the use of a Schrödinger cat state. This enables simultaneous Ramsey interferometry on both isotopes with a spin coherence time of 60 s. We achieve a magnetic noise suppression factor exceeding 3 × 104, and determine the 171Yb–173Yb ratio of nuclear magnetic moments to be –0.726076(3) with a 4-ppm precision. Our results establish a new cold-atom platform for spin-based sensing and open pathways towards quantum-enhanced searches for physics beyond the Standard Model. A cold-atom comagnetometer based on the nuclear spins of 171Yb and 173Yb is demonstrated. A spin coherence time of 60 s is achieved for both isotopes. The 171Yb–173Yb ratio of nuclear magnetic moments is determined as –0.726076(3) with a 4-ppm precision.
Hanbury Brown and Twiss interferometry was a milestone experiment that transformed our understanding of the nature of light. Originally demonstrated in 1956 to measure the radii of stars through photon-correlation detection, it later became a cornerstone of modern quantum optics. Here we connect Hanbury Brown and Twiss interferometry to the physics of scintillation, the process of spontaneous light emission upon excitation by high-energy particles, such as X-rays. By revealing the underlying photon bunching in the scintillation process, we use the photon correlations $${g}^{\left(2\right)}\left(\tau \right)$$ to quantify the intrinsic light emission properties of the scintillator, specifically the emission time and the number of optical photons emitted per X-ray photon. This approach provides a characterization method that we benchmark on a wide gamut of scintillators, including several rare-earth-doped (and undoped) oxide single-crystal scintillators and perovskite nanocrystals, thereby showing the dependence of their properties on temperature and X-ray flux. Our method is particularly important for nano- and microscale scintillators, whose properties are challenging to quantify by conventional means. We extract the scintillation properties even in quantum-dot superlattices of only a few hundreds of nanometres and observed strong photon bunching ( $${g}^{\left(2\right)}\left(0\right) > 50$$ ). Our research paves the way for the broader use of methods from quantum optics for studying materials with complex optical properties in extreme regions of the electromagnetic spectrum. Photon bunching is observed in the scintillation process upon excitation by X-rays. The photon intensity correlation function is measured by using Hanbury Brown and Twiss interferometry to extract the light yield and emission lifetime in scintillator materials.
Photonic integrated circuits commonly feature visible or near-infrared lasers that are vulnerable to destabilizing back-reflections and must be protected by isolators-non-reciprocal optical components enforcing one-way light propagation. Despite recent progress, high-performance isolators remain bulky off-chip components, while on-chip implementations suffer from challenging fabrication, high optical absorption or narrow optical bandwidth. Here we propose and experimentally demonstrate a magnet-free, intrinsically broadband travelling-wave isolator built from foundry-compatible components. Using radio-frequency electro-optic modulation to create synthetic motion across four parallel waveguides, we realize dynamic rotating destructive interference that continuously cancels backward-propagating light while leaving forward-propagating light unaffected. We reach ~30 dB peak isolation, maintain >24 dB isolation across a 30-nm-wavelength span with thermo-optic adjustment and show >20 dB isolation for two lasers simultaneously within 10 nm without any adjustment. The demonstration's 770-800-nm-wavelength span covers key alkali atomic transitions, enabling on-chip laser isolation for atomic spectroscopy, laser cooling and locking applications. Our isolator approach, applicable from the visible to telecom wavelength spectrum, offers a compelling practical solution, opening the way for fully integrated atomic clocks, quantum sensors, advanced telecommunications and tunable laser systems on a single chip.
High-harmonic generation underpins attosecond science. For over three decades, high-harmonic upconversion has been framed within the confines of a single-active-electron light-matter interaction featuring a well-defined cutoff photon energy. Here we demonstrate experimentally that correlated electrons can propel high-harmonic emission beyond this single-active-electron limit, markedly increasing the generated photon energies. We observe a weak secondary plateau that extends the conventional cutoff beyond 120 eV up to the water window at 280 eV. This phenomenon arises from double-electron recombination of strongly correlated electron pairs, resulting in a new cutoff scaling of up to 5.5 times the ponderomotive energy of the rescattering electrons, which notably deviates from the conventional scaling factor of 3.2. These findings reshape our fundamental understanding of the high-harmonic upconversion process and position high-harmonic generation as a potent photonic probe of attosecond-to-femtosecond electron correlations in quantum systems, opening new pathways for advanced ultrafast spectroscopy, novel attosecond source development and the exploration of strongly correlated quantum materials.
Producing on-target laser intensities much greater than 1023 W cm−2 with current laser technologies is a roadblock to accessing new regimes of physics such as strong-field quantum electrodynamics. Laser–plasma amplifiers show promise to realize these intensities by augmenting the final amplifier and compressor in traditional chirped-pulse-amplification architectures with a plasma-based amplification and compression stage that operates at a much higher damage threshold. Here we demonstrate amplification of an ultrabroadband (>60 nm) pulse in a laser–plasma Raman amplifier. We directly amplified seed intensities up to 3.7 × 1015 W cm−2 and measured efficiencies up to 8.7%. Single-shot SPIDER measurements show a factor-of-2 reduction in the amplified pulse duration with final powers up to 0.3 TW, a 10× improvement over previous results. Final pulse durations of 64 fs are measured. Energy transfers greater than 220 mJ from the picosecond pump into the seed result in a 30× energy amplification of a 7.6 mJ seed. These results set the stage for a compact plasma afterburner based on Raman amplification that could extend the scientific capability of existing petawatt-class laser facilities to enable experiments at the intensity frontier. The researchers demonstrate amplification of an ultrabroadband pulse in a laser–plasma Raman amplifier, achieving efficiencies of up to 8.7%, final powers of up to 0.3 TW, and final pulse durations of 64 fs.
Spin light-emitting diodes are promising for applications in next-generation optoelectronics, spin photonics and communication devices. However, rapid spin relaxation at room temperature causes early loss of spin polarization, constraining the asymmetric electroluminescence brightness (BCP-EL, the product of the electroluminescence dissymmetry factor and luminance) to suboptimal levels of 10–1,000 cd m−2. Here we realize a hybrid chiral perovskite heterostructure that features distributed achiral emitters spatially separated by a wide-bandgap chiral spin injector, enabling modulation of the effective contribution of exciton–exciton interactions to spin relaxation. The hybrid chiral perovskite suppresses the rapid rise of the spin-flip rate with excitation density and extends the spin-relaxation time to the nanosecond regime while preserving a photoluminescence quantum efficiency of 78%. The resulting spin light-emitting diodes deliver a BCP-EL of 13,084 cd m−2, a maximum electroluminescence dissymmetry factor of 0.2 and an extrapolated half-lifetime that exceeds 5,000 h at an initial luminance of 100 cd m−2. Kinetic analysis further reveals a crossover in the dominant determinant of emission polarization, from initial spin polarization at low excitation to spin-flip rate at high excitation. These findings provide mechanistic insights into spin dynamics, opening up opportunities for next-generation displays and quantum technologies. Modulating exciton–exciton interactions in hybrid chiral metal halide heterostructures suppresses spin relaxation, enabling spin light-emitting diodes that directly emit circularly polarized light with a dissymmetry factor of 0.2 and a half-lifetime of 5,000 h at an initial luminance of 100 cd m−2.
Communication through optical fibres experiences limitations due to chromatic dispersion and nonlinear Kerr effects that degrade the signal. Mitigating these impairments is typically done using complex digital signal processing algorithms. However, these equalization methods require substantial power consumption and introduce high latencies. Photonic reservoir computing (a subfield of neural networks) offers an alternative solution—processing signals in the analogue optical domain. Here we present, to our knowledge, the first experimental demonstration of the real-time equalization of fibre distortions using a silicon photonics chip that combines the recurrent reservoir and the programmable read-out layer. We successfully equalize a 28-Gbps on–off keying signal across varying power levels and fibre lengths, even in the highly nonlinear regime. We obtain bit error rates that are orders of magnitude below previously reported optical equalization methods, reaching as low as 4 × 10−7, far below the generic forward error correction limit of 5.8 × 10−5 used in commercial Ethernet interfaces. Researchers experimentally demonstrate the real-time equalization of fibre distortions using a silicon photonics chip. The team equalizes a 28-Gbps on–off keying signal and obtains bit error rates as low as 4 × 10−7.
Optical microcavities are widely used as transducers for gas sensing, yet their performance is constrained by a natural trade-off between sensitivity and dynamic range. Here we introduce a laser-tagging optofluidic microcavity that overcomes this limitation, enabling hydrogen detection across a concentration range spanning from the single-molecule level to 1.53 × 105 ppm. The architecture features a hollow whispering-gallery-mode microcavity, functionally coated on its interior surface with a Pt/WO3 nanofilm. Gas detection is mediated via thermal phonon transfer, which allows efficient gas–material interaction without perturbing the optical field, preserving an ultrahigh intrinsic Q factor of 1.89 × 109 during sensing. Through so-called laser tagging, a probe laser is dynamically locked to the microcavity’s optimal operating point, enabling real-time resonance tracking. This scheme not only suppresses phase noise by more than three orders of magnitude but also facilitates wide-bandwidth optoelectronic heterodyne demodulation. We achieve hertz-level frequency-shift resolution and a measurable resonance shift of up to 1 GHz, allowing the sensor to detect hydrogen concentrations from 3 × 10−5 ppm to 1.53 × 105 ppm. With lock-in amplification, even individual molecular dynamics can be resolved. The device’s integrated, centimetre-scale footprint ensures robust operation outside the laboratory, offering a universal strategy to advance optical microcavities towards ultraprecise metrology applications. Laser tagging in an optofluidic microcavity enables precise hydrogen concentration detection across a broad dynamic range. Using thermal phonon transfer and dynamic resonance tracking, this spectrometry method achieves high sensitivity, low noise and effective selectivity.
Intelligent three-dimensional displays require both powerful computing capabilities and high display performance, yet these metrics have long been constrained by the inherent trade-off between efficiency and image quality. Here we introduce circularly polarized bulk-heterojunction memory-computing organic light-emitting diodes featuring an integrated memory-processing-display architecture to break this long-standing limitation. The bulk-heterojunction memory-computing organic light-emitting diode incorporates a chiral bulk-heterojunction active layer formed by an achiral emissive polymer and chiral small molecules. Through precise control of the blend composition, we co-engineer supramolecular ordering and carrier dynamics, enabling the in situ modulation of synaptic weights and multilevel conductance states. This effectively transforms organic light-emitting diodes from passive light emitters into an integrated memory-computing-display system with enhanced computing efficiency and polarized emission. The optimized device achieves a peak luminance of 22,306 cd m−2, a high circularly polarized electroluminescence dissymmetry factor of 0.92, together with ultralow energy consumption of 1.78 pJ per spike. Hardware validation using a 64 × 64 device array demonstrates uniform and distinguishable 5-bit conductance distributions, with an energy consumption of 0.046 nJ per device and 17.472 nJ per pixel per computation. We further integrate our bulk-heterojunction memory-computing organic light-emitting diodes into a neural radiance field framework, enabling stereoscopic greyscale three-dimensional scene reconstruction on 100 × 180 arrays. This memory-computing-display integration strategy provides a promising pathway towards intelligent display technologies. Circularly polarized memory-computing organic light-emitting diodes integrate three-dimensional displays with memory and processing capabilities. Optimized devices achieve luminance of over 22,000 cd m−2, dissymmetry factor of 0.92 and energy consumption down to 1.78 pJ per spike, enabling neural radiance field greyscale three-dimensional scene reconstruction.
Universal photon-based quantum computing requires optical nonlinearities, which can be induced by intermediate measurements and by adaptivity, to be supplied to linear-optical elements. In a near-term perspective, it is essential to probe whether dynamics going beyond linear optics can be accessed with a limited amount of resources. Although recent results show how linear-optical dynamics implies bounds on the set of photonic states that can be generated, quantitative methods for studying the emergence of nonlinear dynamics are largely missing. Here we analyse a regime in which such bounds can be surpassed. We do this by leveraging an adaptive boson sampling architecture in which the optical evolution implemented in a photonic device is progressively adapted via measurement-based feedback. We introduce practical methods to quantify the emergence of a gap with respect to linear optics and derive nonlinearity witnesses from the properties of linear-optical evolution. Then, we validate the toolbox developed within adaptive boson sampling architectures of increasing complexity implemented on a state-of-the-art photonic platform, both by realizing real-time adaptivity and by emulating adaptive protocols via post-selection for more complex configurations. In particular, we probe experimentally a regime in which nonlinear dynamics, unobtainable within a linear-optical paradigm, can arise, thus showing how optical architectures with limited adaptivity are a powerful testbed for exploring new regimes.
The dynamics of an electronic wavefunction often have non-trivial consequences on its spatial distribution, for example, during tunnelling or chemical bond formation. Yet, revealing spatio-temporal coupling requires ultrafast videography at the intrinsic size of electronic wavefunctions, at the so-called space-time limit. Here we experimentally access the intrinsic quantum motion of individual electrons at the space-time limit while they are tunnelling through an energy barrier, using atomic-scale lightwave-driven scanning tunnelling microscopy with attosecond time resolution. While modulating the tunnelling barrier with two time-delayed near-infrared pulses forming phase-controlled single-cycle waveforms, isolated electron tunnelling transients shorter than 1 fs are identified. The measured spatial extension depends on the interplay of multi-photon and field-driven dynamics, as confirmed by full quantum simulations. We experimentally localize the attosecond-confined tunnelling wave packet on the angstrom scale and use it to map a single copper adatom on a silver surface. This fusion of attosecond science with atomic-scale scanning tunnelling microscopy makes it possible to study wavefunction dynamics inside atoms, molecules and solids.
A new nanophotonic sensing strategy converts even subtle refractive-index changes into large intensity variations via radiative Q-factor modulation. Implemented in a bound-state-in-the-continuum (BIC) metasurface, the concept enables ultrasensitive and scalable biosensing of only a few tens of tumour extracellular vesicles within 15 minutes.
Ultrafast spatio-temporal shaping of ultra-intense laser pulses is an important yet challenging goal. Now, researchers have synthesized light into a spring-like form, at relativistic intensities. The advance may provide control over the angular momentum degrees of freedom of matter at relativistic intensity, leading to previously unexplored forms of laser–plasma interactions in the laboratory.
Polar cocrystals made from two centrosymmetric components use quantum coherent beating to enhance photothermal conversion, setting a new high temperature for organic solids exposed to laser light.
A novel spectroscopic method using the interaction between light and matter via chirality was reported at the Japan Society of Applied Physics Spring Meeting.
A non-interferometric imaging framework enables quantitative 3D reconstruction of full dielectric tensors, opening a practical route to volumetric optical measurement of biaxial anisotropy in complex materials and biological structures.
