A quantum scan was a scan on the quantum level of an object.
In September 2153, quantum scans of a Delphic Expanse sphere indicated it was nearly one thousand years old. (ENT: "Anomaly")
Some months later, Enterprise NX-01's quantum scans dated the earliest structures of a Skagaran colony at over two hundred and fifty years old. (ENT: "North Star")
In 2373, Miles O'Brien intended to run a quantum scan on a data crystal in an effort to decode the crystal's contents. (DS9: "A Simple Investigation")