Scientists at Johns Hopkins Applied Physics Laboratory (APL) are developing a quantum sensing platform that could eventually let warfighters detect chemical and biological threats with a device small enough to carry into the field.

The system is designed to combine the broad detection capabilities of nuclear magnetic resonance (NMR) spectroscopy with the portability of a much smaller sensor. APL researchers envision a fieldable device roughly the size of a laptop that could analyze extremely small samples of potentially hazardous substances.

NMR spectroscopy uses magnetic fields to manipulate the spins of atomic nuclei. The resulting signals contain information about the structure of molecules, allowing researchers to distinguish between different substances.

The technique is already widely used in laboratories, but conventional NMR systems are difficult to take into the field. They typically require powerful superconducting magnets, cryogenic cooling equipment, and relatively large sample volumes.

APL experimental physicist Isaiah Gray and his team are pursuing a different approach based on nitrogen-vacancy (NV) centers in diamond.

An NV center is created when a nitrogen atom replaces a carbon atom in a diamond and a neighboring carbon atom is missing. This creates a quantum system that responds to surrounding magnetic fields.

When illuminated with green laser light, the NV center emits red light. By measuring that light, researchers can determine the NV center’s spin state and use it to infer information about nearby molecular structures.

The approach can potentially work with samples containing only tens or hundreds of atoms, dramatically reducing the amount of material required compared with conventional NMR.

Source link