Research articles

Researchers use a nonlinear coherent imaging technique to demonstrate distant coherent coupling between excitons in quantum wells. The long-range nature of the coupling is attributed to the existence of spatially extended exciton states up to the micrometre range.

Researchers demonstrate the first laser confined in all three spatial dimensions by a three-dimensional photonic crystal. The device, in this case driven by quantum dots, represents the long-standing goal of achieving lasing in a cavity formed entirely by a complete-photonic-bandgap medium.

The diffraction of light scales with wavelength, thereby placing fundamental limits on applications such as imaging, microscopy and communications. Here, researchers experimentally demonstrate scale-free propagation in supercooled structures and cancel diffraction, instead of merely compensating for it, as is the case for most approaches in nonlinear optics.

Entangled photon states, obtained by post selection, are used to perform interferometric phase measurement with a sensitivity beyond the shot-noise limit.

Scientists demonstrate an optical analogue of aerodynamic lift, in which an airfoil-shaped refractive object can be controlled through the radiation pressure induced by refracted and reflected rays of light.

Scientists demonstrate a fully integrated and scalable waveguide chip that can control the polarization and intensity of light using a row of independent atomic junctions. The device may enable quantum states of matter and light to be engineered on a microscopic scale.

Researchers report the direct observation of ultrafast magnetic dynamics using the magnetic component of highly intense terahertz wave pulses with a time resolution of 8 fs. This concept provides a universal ultrafast method of visualizing magnetic excitations in the electronic ground state.

Researchers demonstrate a probabilistic noiseless linear amplifier based on photon addition and subtraction. The technique enables coherent states to be amplified to the highest levels of effective gain and final-state fidelity, and could become an essential tool for applications in quantum communication and metrology.

Using ∼1-mm-long photonic crystal waveguides, scientists experimentally demonstrate the compression of 3 ps pulses to a minimum duration of 580 fs at a low pulse energy of ∼20 pJ. The approach may pave the way for soliton applications in integrated photonic chips.

Researchers report rewritable nanoscale photodetectors that exploit 2–3 nm nanowire junctions. Large electromagnetic fields in the gap region aid the detector response, which is electric-field-tunable and spans the visible to near-infrared regime.

Researchers report the generation of isolated sub-160-attosecond pulses that have photon energies of 30 eV, resulting in an on-target pulse energy of a few nanojoules. The availability of attosecond sources with high peak intensities may open new avenues for attosecond pump/probe studies of electronic processes in atomic and molecular physics.

Researchers demonstrate a coherent dual-comb-based spectrometer capable of measuring continuous-wave optical waveforms at time resolutions of 30 µs and 320 µs over terahertz bandwidths. The device is potentially useful for sensing applications such as multispecies gas detection, coherent laser radar and optical metrology.

It is well-known that neutral atoms can be trapped using visible light, but the trapping of ions is typically achieved using radiofrequency electromagnetic fields. Researchers have now developed an optical ion trapping technique that may be useful for applications ranging from quantum physics to ultracold chemistry.

By combining advanced ultrashort-pulse laser technology with scanning tunneling microscopy, scientists demonstrate that they can directly image transient carrier dynamics in nanostructures in real space.

Quantum entanglement — used for quantum key distribution, communication and teleportation — is a fragile resource. Researchers investigate the conditions under which optical loss destroys entanglement, and report states that are particularly robust to such losses.

Colour conversion of single photons may allow the advantages of quantum systems operating at different wavelengths to be simultaneously utilized. Researchers demonstrate the colour conversion of triggered single photons from a semiconductor quantum dot between 1.3 µm to 710 nm. The up-converted signal maintains the quantum character of the original light.

Researchers demonstrate the generation of deep-ultraviolet light of wavelength ∼240 nm from Al_xGa_1−xN/AlN quantum wells by electron beam irradiation, with an output power of 100 mW and an efficiency of ∼40%. This record-breaking power is attributed to the high crystalline quality of the quantum wells and the proper well design for electron beam pumping.

A prototype microscope built with self-reconstructing Bessel beams is shown to be able to reduce scattering artifacts as well as increase image quality and penetration depth in three-dimensional inhomogeneous opaque media.

Devices that can reduce noise in fibre-optic communications systems are of great technical importance. Scientists have now developed a practical all-optical regenerator that is capable of directly removing not only amplitude noise but also phase noise from binary phase-encoded optical communications signals.

Researchers exploit atomic quantum state control in a fully integrated photonic atomic spectroscopy chip to reduce the group velocity of light by a factor of 1,200 — the lowest group velocity ever reported for a solid-state material. The findings will enable the creation of on-chip nonlinear optical devices with enhanced quantum coherence operating at ultralow power levels.