This thesis reports on the development of the first quantum enhanced
microscope and on its applications in biological microscopy. The first
quantum particle-tracking microscope, described in detail here,
represents a pioneering advance in quantum microscopy, which is shown to
be a powerful and relevant technique for future applications in science
and medicine.
The microscope is used to perform the first quantum-enhanced biological
measurements -- a central and long-standing goal in the field of quantum
measurement. Sub diffraction-limited quantum imaging is achieved, also
for the first time, with a scanning probe imaging configuration allowing
10-nanometer resolution.