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Experimental investigation of the reverse-Doppler shift of electromagnetic waves has previously been restricted to the microwave regime. Here, direct confirmation of the Doppler effect is reported at the infrared wavelength of 10.6 µm using a moving photonic crystal exhibiting a negative refractive index.
Based on peristaltic nematogen microflows in polydimethylsiloxane, scientists demonstrate an optofluidic modulator that exhibits a symmetric 250 µs response and can operate at frequencies of up to 1 kHz.
Many X-ray imaging techniques require transmission geometries, which place severe restrictions on the samples being imaged. Here, a reflection geometry lensless X-ray imaging method is demonstrated. This technique may allow single-shot imaging of surfaces and films such as organic photovoltaic materials and field-effect transistor devices, or Bragg planes in a single crystal.
Combining semiconductor quantum dots and atomic systems allows the light emitted from a quantum dot to be temporarily stored. Here, scientists describe a hybrid semiconductor-atomic interface that can slow down a single photon emitted from a quantum dot by 15 times its temporal width. The findings are attractive for the implementation of quantum memories and quantum repeaters.
Scientists describe a size-selective quantum dot patterning technique that involves kinetically controlling the nanotransfer process without a solvent. The resulting printed quantum dot films exhibit excellent morphology and a well-ordered quantum dot structure. This technique allows fabrication of a 4-inch (or larger) thin-film transistor display with high colour purity and extremely high resolution.
Based on a CMOS-compatible growth process, researchers successfully demonstrate the bottom-up integration of InGaAs nanopillar lasers onto silicon chips. The resulting nanolaser offers tiny footprints and scalability, making it particularly suited to high-density optoelectronics.
Researchers exploit a dielectric planar antenna to tailor the angular emission of single photons from an oriented molecule. Record collection efficiency of 96% and detection rates of 50 MHz are demonstrated using a microscope objective at room temperature.
Next-generation X-ray sources have allowed new opportunities for ultrafast imaging, but such schemes require femtosecond synchronization between the pump and probe laser pulses. Here, researchers present few-femtosecond timing between a free-electron laser and an external laser exploiting terahertz radiation.
Fourier-transform spectroscopy offers high resolution, wavelength accuracy and broad tunability, but is so far limited to the mid-ultraviolet range, down to wavelengths of 140 nm. Now, based on a wavefront-division scanning interferometer, researchers present a Fourier-transform spectroscopy scheme that covers a broad wavelength range of 40–250 nm with 7% tunability and an extrinsic absolute wavelength accuracy of 10−7.
Scientists demonstrate a cavity-stabilized laser system with a reduced thermal noise floor, exhibiting a fractional frequency instability of 2 × 10−16. They use this system as a stable optical source in an ytterbium optical lattice clock to resolve an ultranarrow 1 Hz linewidth for the 518 THz clock transition. Consistent measurements with a clock instability of 5 × 10−16/√τ are reported.
Spectral modulation of a broadband pump beam allows sensitive and specific molecular imaging based on stimulated Raman scattering. Measurements of cholesterol, protein, and stearic and oleic acid are reported.
Focusing into a scattering medium is much more valuable than focusing through it. Scientists now demonstrate the dynamic focusing of light into a scattering medium by combining the ultrasonic modulation of diffused coherent light with optical phase conjugation.
Highly sensitive absorption spectroscopy is used to image the presence of single molecules through their weak optical absorption signatures. Measurements are demonstrated at mutiple wavelengths and scanned over a 2D area to create spatial maps of absorption.
Researchers demonstrate an X-ray holography method that records two independent images spaced by a femtosecond variable time delay. The concept overcomes the time limitations of two-dimensional area detectors by superimposing the separable X-ray holograms in a single detector exposure.
Laser spectroscopy based on the nonlinear photothermal and photoacoustic spectral resonances of nanoparticles is demonstrated. This approach will be potentially useful for applications such as multispectral imaging, multicolour cytometry, and the study of laser–nanoparticle interactions at a resolution beyond the spectral limit.
Researchers propose a new type of multiphoton entangled state and demonstrate its working principles of measurement-based quantum computation in correlation space. With four- and six-qubit states, they realize a universal set of single-qubit rotations, two-qubit entangling gates and further Deutsch's algorithm.