Sagnac-witnessed laser deflection is an ultra-sensitive acoustic detector.

Laser-deflection-based acoustic sensing is known for high bandwidth but low sensitivity. By embedding the sensing laser within a Sagnac interferometer and incorporating split-beam detection-originally developed for optical trapping microscopy-we demonstrate sensitive acoustic detection in air with a 2 MHz bandwidth. In a direct comparison, our method far-exceeds performance metrics of a state-of-the-art, commercially-available, high-bandwidth microphone.

Monitoring damage of self-assembled monolayers using metastable excited helium atoms.

The breaking of molecular bonds during exposure to ionizing radiation and electron beams creates irreversible damage in the molecular structure. In some cases, such as lithography, controlled damage of a molecular resist is a desirable process and is the basis for the entire semiconductor industry. In other cases, such as environmental exposure or probing of the molecular structure, the induced damage is a major problem that has limited advances in science and technology.

Brownian motion as a new probe of wettability.

Understanding wettability is crucial for optimizing oil recovery, semiconductor manufacturing, pharmaceutical industry, and electrowetting. In this letter, we study the effects of wettability on Brownian motion. We consider the cases of a sphere in an unbounded fluid medium, as well as a sphere placed in the vicinity of a plane wall.

Communication: Neutral atom imaging using a pulsed electromagnetic lens.

We report on progress towards a neutral atom imaging device that will be used for chemically sensitive surface microscopy and nanofabrication. Our novel technique for improving refractive power and correcting chromatic aberration in atom lenses is based on a fundamental paradigm shift from continuous-beam focusing to a pulsed, three-dimensional approach. Simulations of this system suggest that it will pave the way toward the long-sought goal of true atom imaging on the nanoscale.

Broadband boundary effects on Brownian motion.

Brownian motion of particles in confined fluids is important for many applications, yet the effects of the boundary over a wide range of time scales are still not well understood. We report high-bandwidth, comprehensive measurements of Brownian motion of an optically trapped micrometer-sized silica sphere in water near an approximately flat wall. At short distances we observe anisotropic Brownian motion with respect to the wall.