Letters in 2012

A parallel implementation of multifocal multiphoton modulation microscopy allows simultaneous phosphorescent lifetime and intensity imaging in vivo at speeds 100 times faster than conventional configurations. Three-dimensional imaging of a phosphorescent quenching dye is also presented.

Experimental demonstration of Anderson localization in three dimensions is a challenging task. Here researchers present a direct and absorption-independent measure of the localization length and evidence for a localization transition in three dimensions.

Researchers report the entanglement-enhanced measurement of a delicate material system, in which they non-destructively probe an ⁸⁵Rb atomic spin ensemble by near-resonant Faraday rotation. They use narrowband, atom-resonant ‘NOON’ states to beat the standard quantum limit of sensitivity by more than five standard deviations, both on a per-photon and a per-damage basis.

Researchers focus 10 keV X-ray free-electron laser radiation to an area of 0.95 µm × 1.20 µm with near-100%-efficiency using reflective optics. This approach increases the fluence by a factor of 40,000 and provides a power density of 6 × 10¹⁷ W cm⁻².

Researchers demonstrate large cross-phase shifts of 0.3 mrad per photon in a single pass through room-temperature Rb atoms confined to a hollow-core photonic bandgap fibre. The response time of less than 5 ns indicates that phase modulation bandwidths greater than 50 MHz are possible with a highly sensitive atomic-vapour-based scheme.

Coherent control is a powerful tool for controlling light–matter interactions in time and frequency. Now, scientists show that counter-propagating broadband pulses can be used to generate fully controlled spatial excitation patterns. This spatial control approach also reduces decoherence, providing a high-frequency resolution similar to that of an optical frequency comb.

Scientists demonstrate a simple approach for separating a nonlinearly generated attosecond pulse train into multiple beams of isolated attosecond pulses that propagate in different and controlled directions away from the plasma surface. The approach involves rotating the propagation direction of an intense few-cycle laser field as it interacts with a solid-density plasma.

Researchers optically control an active medium. Strong light-matter interaction causes superdiffusion that is controllable by the input optical power. The idea may be applied to exploring nonequilibrium thermodynamics of soft-matter or enable new possibilities for the coherent control of strongly coupled, complex systems.

A photoelectrochemical cell made from combining a dye sensitized solar cell with a semiconductor-oxide photoanode is demonstrated to perform water splitting with an efficiency of up to 3.1%. As the scheme uses relatively inexpensive materials and fabrication techniques it could provide a cost effective approach to hydrogen production.

Researchers bring together silk and photonic crystals and report the manufacturing of robust, freestanding, three-dimensional photonic crystals with different lattice constants in the structural form of an inverse opal entirely composed of silk fibroin. These silk-based inverse opals add a new dimension at the interface of nanophotonics and biological applications.

By using qubit recycling, researchers demonstrate a scalable version of Shor's algorithm in which the total number of qubits is one third of that required in the standard protocol. They experimentally implemented a two-photon compiled algorithm to factor N = 21, pointing to larger-scale implementations of Shor's algorithm.

Researchers describe a path towards 5 × 10¹⁴ fully coherent soft X-ray photons in 200 fs pulses reaching 20 GW peak power. The proposed amplification scheme is based on seeding stretched high harmonics using a transposition of Chirped Pulse Amplification to soft x-rays.

The mechanism by which various species of silvery fish produce almost perfect broadband, polarization-neutral reflections is revealed. The answer lies with the use of multilayers composed of two types of birefringent guanine crystals, which each have their extraordinary and ordinary refractive indices orientated in different directions.

Researchers demonstrate a chip-scale optomechanical accelerometer with displacement read-out using a photonic crystal cavity integrated with a tethered nanogram test mass of high mechanical Q-factor. The device achieves an acceleration resolution of 10 µg Hz^−1/2 for sub-mW optical power, a bandwidth greater than 20 kHz, and a dynamic range of 50 dB.

Efficient four-wave-mixing process in silicon nanophotonic wires facilitates spectral translation of a signal at 2,440 nm to the telecommunications band at 1,620 nm across a span of 62 THz. This approach helps eliminate cooling requirements for the narrow-bandgap semiconductors traditionally used to detect mid-infrared photons.

Researchers use spatially shaped light to control the direction of spin-wave emission from the ferrimagnetic insulator Gd_4/3Yb_2/3BiFe₅O₁₂. They capture the essential features of the observations by employing a simple model that maps the spatial profile of the pump pulse onto the dispersion relation of the spin wave.

Researchers describe an optical method for switching off or modifying the light emission from cells transfected with green fluorescent protein. The scheme uses the precise delivery of femtosecond laser light to induce the release of reactive oxygen species within the cell, which bleaches the fluorescence.

Researchers show that digital optical phase conjugation can be used to achieve focusing at record depths in highly scattering media, and report fluorescence imaging beyond the ballistic regime with a three-dimensional confined sound-modulation zone.

Polymer solar cells are lightweight and may represent a low-cost source of energy, although efficiency still prohibits many practical applications. Here researchers demonstrate polymer solar cells with a certified efficiency of 9.2%. This is achieved by employing an inverted structure that aids photogenerated charge-carrier collection and photon harvesting.

Researchers experimentally realize the quantum delayed-choice experiment and show that the quantum wave–particle superposition is clearly different from the classical mixture by comparing interference fringes under various conditions. This work reveals the deep relationship between the complementarity principle and the superposition principle of light.