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Some X-ray free-electron laser facilities are pushing towards sub-10 fs pulses, making it desirable to reduce errors in X-ray/optical delay measurements to the 1 fs level. Researchers have now demonstrated X-ray measurements with a temporal resolution shorter than 1 fs, opening up new possibilities for time-resolved X-ray experiments.
Trapping of a terahertz wave in a photonic-crystal slab and subsequent ‘capture’ through absorption are demonstrated. Over 90% of the wave lying within 17% of the centre frequency is absorbed. Application to the stabilization of terahertz wireless communication systems is shown.
Scalable methods employing a random unitary chip and a quantum walk chip are developed to experimentally verify correct operation for large-scale boson sampling. Experimental analysis reveals that the resulting statistics of the output of a linear interferometer fed by indistinguishable single-photon states exhibits true non-classical characteristics.
A high-resolution, broadband imaging system based on coherent anti-Stokes Raman spectroscopy performs rapid, chemically specific imaging of biological tissue. It employs three-colour excitation and operates across the entire biological window.
The phase of a collection of spins is measured with a sensitivity ten times beyond the limit set by the quantum noise of an unentangled ensemble of 87Rb atoms. A cavity-enhanced probe of an optical cycling transition is employed to mitigate back-action associated with state-changing transitions induced by the probe.
The generation of a left-handed torque that acts in the opposite direction to light's natural spin angular momentum is reported. The effect is achieved by sending circularly polarized light into an azimuthally patterned birefringent glass disk.
The vibrations of the chemical bonds of a single molecule are observed by employing time-resolved coherent anti-Stokes Raman scattering. A gold nanoantenna is used to enhance the signal from the molecule.
A suite of flexible, integrated, high-index-contrast chalcogenide glass photonic devices, including waveguides, microdisk resonators, add–drop filters and photonic crystals, is reported. The devices are demonstrated to survive repeated bending to a submillimetre radius without any significant degradation in their optical performance.
Active metamaterials have been used to realize terahertz imaging with a single-pixel detector. Compressive techniques permit high-fidelity images to be acquired at high frame rates. The technique involves no moving parts and yields improved signal-to-noise ratios over standard raster scanning techniques.
A photothermal imaging scheme that is analogous to optical coherence tomography can be used to construct the three-dimensional structures of bone and burn-affected skin.
Extreme-ultraviolet frequency combs have previously been used to realize spectroscopy with a megahertz level resolution, but higher resolutions are desired for precision-measurement applications. Now, a sub-hertz spectral resolution is demonstrated, which corresponds to coherence times of over 1 s at photon energies up to 20 eV; such coherence times are over six orders of magnitude longer than those previously reported.
Hybrid entanglement between a quantum single-photon qubit state and a classical one is experimentally generated by quantum-mechanically superposing non-Gaussian operations on distinct modes. Entanglement is clearly observed between the two different types of generated states. This method provides a feasible way to generate even larger hybrid entanglement.
On-chip parity–time-symmetric optics is experimentally demonstrated at a wavelength of 1,550 nm in two directly coupled, high-Q silica microtoroid resonators with balanced effective gain and loss. Switchable optical isolation with a nonreciprocal isolation ratio between −8 dB and +8 dB is also shown. The findings will be useful for potential applications in optical isolators, on-chip light control and optical communications.
To address the controversy regarding the validation of an experiment that is hard to simulate, boson-sampling experiments are implemented with three photons in randomly designed integrated chips with up to 13 modes. It is experimentally demonstrated that the Aaronson–Arkhipov test allows boson-sampling experiments to be distinguished from uniformly drawn samples.
Optical entanglement between a particle-like subsystem and a wave-like one is generated through the heralding detection of a single photon in an indistinguishable fashion at a central station. This enables information to be converted from one Hilbert space to the other via teleportation, and hence permits remote quantum processors based on different encodings to be connected.
A simple method is demonstrated for high-order harmonic generation with fully controlled (linear, elliptical and circular) polarization. Its conversion efficiency is comparable to those of conventional high-order harmonic methods. This technique potentially has a broad range of applications from ultrafast circular dichroism to attosecond quantum optics.
An optical-frequency-comb laser manipulating a dipole response can imprint the comb on an excited transition with a high photon energy. The concept can be implemented using existing X-ray technology.
A cavity quantum electrodynamics system comprising a quantum emitter and an optical cavity is theoretically investigated. The outcoupling process for the N-photon state of the cavity is simulated. The numerical calculations predict the possibility of operating this system as a source of N-photon bundles with a tunable integer N.
The long-standing question of information velocity in slow- and fast-light media is investigated by measuring the propagation time of random and correlated noise. The mutual information shared between two modes of an entangled state of light was found to advance when one mode propagates through the fast-light medium.
