Volume 19 Issue 2, February 2025

Sir Peter Knight, described as "one of the UK’s most influential scientists and leaders of scientific policy" by his peers, tells Nature Photonics about the many hats he is wearing now in pushing quantum research and technologies in the UK and beyond.

Champion experimentalist of quantum optics and squeezed-light pioneer has sadly passed away.

An intrinsic optical bistability, independent of thermal effects, is identified in Nd³⁺-doped photon avalanching nanoparticles at low temperatures, enabling high-contrast, transistor-like optical responses.

Mode coupling and purity degradation have long challenged vortex photonics. A topological disclination lattice waveguide with dual topological protections now offers a solution, enabling robust vortex transmission and precise mode filtering.

Using resonant structures can enhance one of the key features of photonic time crystals while easing practical challenges, bringing their realization at optical frequencies closer to reality and unlocking potential applications in light amplification and next-generation photonic technologies.

The effects of magnetic fields on quantum entangled biomolecules are detected using a highly sensitive magneto-fluorescence fluctuation microspectroscopy technique. This marks an important advance in experimental quantum life sciences at the single-photon level.

Semiconductor sources of mid-infrared and terahertz radiation are now tackling an increasingly diverse range of applications.

Sub-cycle phase-resolved attosecond interferometry is developed. The obtained phase information enables us to decouple the multiple quantum paths induced in a light-driven system, isolating their coherent contribution and retrieving their temporal evolution.

Polarization-entangled photon pairs are generated from two perpendicularly aligned two-dimensional crystals of NbOCl₂. The polarization-entangled state is measured with a fidelity up to 86%. The measured count rate normalized to pump power and interaction length is 472 Hz mW^−1 mm^−1.

Optical realization of photonic time crystals can be achieved by using temporal variations in a resonant material to expand the momentum bandgap, even at low modulation strengths, with known low-loss materials and realistic laser pump powers.

Orbital angular momentum transfer from optical vortex beams to electronic quantum Hall states is reported in a graphene sheet, showing a robust contribution to the radial photocurrent that depends on the vorticity of light.

Topological protection in disclination lattices that relies on non-trivial winding in momentum space and real space is used to confine and guide vortices that feature arbitrary high-order charges. This approach could help in the development of orbital angular momentum-based photonic devices.

The incorporation of fluorine-doped tin oxide nanoplatelets on the substrate of perovskite solar cells contributes to uniform light harvesting across different incidence angles of sunlight. The best devices show a power conversion efficiency of 26.4% (certified 25.9%), 95% of which is maintained after 1,200 hours of operation.

Quantum effects on biological reactions are investigated via magnetosensitive single-photon microspectroscopy. Using single-photon avalanche diode detectors, magnetosensitive radical pair photochemistry is detected to the single-photon level on 23 flavin molecules.

Dark-field momentum microscopy makes it possible to spatio-temporally and spatio-spectrally resolve the dark-exciton dynamics in a twisted transition metal dichalcogenide heterostructure.

An in situ-grown layer of SiO_xN_y contributes to passivating surface defects in inverted organic solar cells, enabling power conversion efficiency of up to 18.49% and an estimated device lifespan of over 16 years.

Researchers demonstrate a compact photonic mmWave radar based on a 4-inch wafer-scale thin-film lithium niobate technology. Multi-target ranging with 1.50 cm resolution and velocity measurement with a resolution of 0.067 m s^−1 are achieved. An inverse synthetic aperture radar with a two-dimensional resolution of 1.50 cm × 1.06 cm is also demonstrated.

Intrinsic optical bistability in Nd³⁺-doped KPb₂Cl₅ avalanching nanoparticles enables high-contrast switching between luminescent and non-luminescent states and transistor-like optical responses. A non-thermal mechanism is discussed and >200th-order optical nonlinearities are shown to be possible.