Konrad Lehnert and his group are working on ultrasensitive devices to: (1) measure currents by directly counting electrons as they flow through a one-dimensional wire, (2) detect the position of nanometer-sized objects with a precision limited only by quantum mechanics, and (3) measure the rise in temperature of a cold surface when it absorbs a single photon of light. Because all three devices incorporate fast, sensitive microwave electronics, they are able to detect changes in temperature, position, or charge that happen faster than a microsecond. The devices will be useful for precision measurements of very small forces, resistance in nanoscale conductors such as molecular wires and carbon nanotubes, and radiant energy at submillimeter wavelengths. Lehnert is also developing ultralow power, superconducting electronics for future space-based observatories.

Jun Ye and his group have developed a powerful enhancement of cavity ringdown spectroscopy for identifying and investigating atoms and molecules. The technique can detect trace amounts of chemicals with exquisite sensitivity because it precisely identifies their characteristic patterns of laser light absorption, or molecular fingerprints. It uses an ultrafast laser to create a wide bandwidth optical frequency comb, which is coupled to an optical cavity containing samples for analysis. The sample absorbs photons of particular frequencies, which are unique for each atom or molecule present. Light exiting the cavity is analyzed to detect and precisely identify sample constituents.

Dana Anderson is investigating an adaptive interferometric sensor for detecting hazardous chemicals. When low concentrations of them are adsorbed onto chemically selective surfaces, they cause observable optical changes. The application of interferometry is made possible by nonlinear holographic media, which allow the system to adapt to temperature, humidity, poor optical wave fronts, and other effects that normally impede precision measurements. The sensor can detect a few tens of parts per billion of certain vapors.