Letters in 2014

A table-top source based on high-harmonic generation produces bright, coherent, quasi-circular pulses of extreme ultraviolet light for probing chiral molecules.

The ability to store arbitrary polarization states of light in an antiferromagnetic material (YMnO₃) potentially adds a new degree of freedom to data storage applications.

The first table-top hard X-ray plasma source driven by a mid-infrared source provides 10^9 photons per pulse.

Combining the principles of time reversal and adaptive control with a spatial light modulator makes it possible to focus light onto moving objects hidden within a scattering medium. The approach could prove useful for medical applications.

A network of four degenerate optical parametric oscillators (OPOs) is employed to find the ground state of the Ising Hamiltonian. The good performance of the network reveals the potential of OPOs for many similar problems.

Laser-based tractor beams move hollow glass particles over tens of centimetres.

Plasmonic nanostructures enable spontaneous emission enhancement factors of greater than 1,000 — the largest observed to date. The orientation of dipole emitters in nanogaps plays a vital role.

The authors demonstrate ultrabroadband time-resolved THz spectroscopy on a single InAs nanowire with 10 nm spatial resolution and sub-100 fs time resolution.

Quantum teleportation of the state of a qubit encoded in the polarization state is demonstrated from a telecom-wavelength photon to a solid-state quantum memory via 24.8 km of optical fibre. It is the longest distance ever reached in a teleportation experiment involving a quantum memory.

Mid-infrared supercontinuum generation with a record-breaking spectral coverage of 1.4–13.3 µm is demonstrated by launching intense ultra-short pulses into short pieces of ultra-high numerical aperture step-index chalcogenide glass optical fibre consisting of a GaAsSe cladding and an As₂Se₃ core.

Teleportation of a photonic qubit is demonstrated on a reconfigurable photonic chip. All of the key elements of the teleportation protocol are performed. The average fidelity for the three linearly independent quantum states is higher than the classical limit, which certifies the capability of teleporting a general quantum state.

High photon flux with up to 10¹² photons in the 25–40 eV range has been achieved in a new table-top coherent extreme ultraviolet (EUV) source based on phase-matched high-harmonic generation using a fibre laser. Intense and compact EUV sources are needed for certain types of spectroscopic and imaging applications.

A soft X-ray ptychography approach can now image 5-nm-sized objects. Chemical component distributions in the delithiation of LiFePO₄ nanoplates — a process relevant for energy storage — links structural defects to chemical phase propagation.

A single-shot burst camera has been developed that can generate motion pictures without performing repetitive measurements. It has a frame rate of 4.4 trillion frames per second and a high pixel resolution of 450 × 450 pixels, making it a powerful tool for observing difficult-to-reproduce or non-repetitive events in real time.

An effective magnetic field is generated on a chip and a non-reciprocal phase shift is demonstrated in an 8.35-mm-long interferometer. The magnitude of the non-reciprocal phase produced is comparable to that achievable with monolithically integrated magneto-optical materials.

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.

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.

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.

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.