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The Gaussian minimum entropy conjecture—a long-standing open question—has now been proved for single-mode phase-insensitive bosonic Gaussian channels. This establishes the ultimate achievable bit rate under an energy constraint and provides long-awaited proof that the single-letter classical capacity of these channels is additive.
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 three-photon entangled Greenberger–Horne–Zeilinger state is directly produced by cascading two entangled down-conversion processes. Experimentally, 11.1 triplets per minute are detected on average. The three-photon entangled state is used for state tomography and as a test of local realism by violating the Mermin and Svetlichny inequalities.
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.
The use of carbon nanotubes makes it possible to perform fluorescent imaging of cerebral vasculature of mice through their intact skulls. The high spatial and temporal resolution of the non-invasive technique may prove useful for studies of stroke and other brain disorders.
Developments in optical materials and components for extreme applications such as the James Webb Space Telescope and petawatt laser systems were showcased at CLEO 2014.
