Phononically shielded photonic-crystal mirror membranes for cavity quantum optomechanics.

We present a highly reflective, sub-wavelength-thick membrane resonator featuring high mechanical quality factor and discuss its applicability for cavity optomechanics. The 88.5 nm thin stoichiometric silicon-nitride membrane, designed and fabricated to combine 2D-photonic and phononic crystal patterns, reaches reflectivities up to 99.

Quantum-Limited Measurements Using an Optical Cavity with Modulated Intrinsic Loss.

We analyze a cavity optomechanical setup, in which the position of an oscillator modulates the internal optical loss. We show that, in contrast to systems with a fixed internal loss, in such a setup, quantum-limited position measurements can be performed and formulate conditions under which it is possible. Additionally, under these conditions the setup exhibits a number of potential benefits for practical operation, including the complete absence of dynamical backaction and optomechanical instability, rejection of classical laser noise, and thermal fluctuations of cavity frequency from the measurement record.

Critical scattering and incommensurate phase transition in antiferroelectric PbZrO under pressure.

Antiferroelectric lead zirconate is the key ingredient in modern ferroelectric and piezoelectric functional solid solutions. By itself it offers opportunities in new-type non-volatile memory and energy storage applications. A highly useful and scientifically puzzling feature of this material is the competition between the ferro- and antiferroelectric phases due to their energetic proximity, which leads to a challenge in understanding of the critical phenomena driving the formation of the antiferroelectric structure.

Free-Carrier-Compensated Charged Domain Walls Produced with Super-Bandgap Illumination in Insulating Ferroelectrics.

Charged domain walls in ferroelectrics are movable and electronically conducting interfaces inside insulating materials. A simple and reliable method for their artificial production with ultraviolet (UV) light is described. The UV illumination produces free carriers in ferroelectric bulk, which simultaneously promotes the formation of charged domain walls and provides charge for their compensation.

Piezoelectric enhancement under negative pressure.

Enhancement of ferroelectric properties, both spontaneous polarization and Curie temperature under negative pressure had been predicted in the past from first principles and recently confirmed experimentally. In contrast, piezoelectric properties are expected to increase by positive pressure, through polarization rotation. Here we investigate the piezoelectric response of the classical PbTiO3, Pb(Zr,Ti)O3 and BaTiO3 perovskite ferroelectrics under negative pressure from first principles and find significant enhancement.