Researchers at the research center QUANTOP at the Niels Bohr
Institute at the University of Copenhagen (Denmark) have
constructed an atomic magnetometer, which has achieved the
highest sensitivity allowed by quantum mechanics. Sensitive
magnetometers could be used to measure electrical activity in
the human brain and heart. The results have been published in
Physical Review Letters. The ultimate sensitivity of any
measurement is determined by the laws of quantum mechanics.
These laws, normally most noticeable at the atomic level, become
relevant for larger objects as the sensitivity of measurements
increase with the development of new technologies. Atoms as
magnetic sensors Atoms have a fundamental property called spin,
which makes the atoms act like small magnets that are sensitive
to external magnetic fields and can be used as magnetic sensors.
But each of the atomic spins has a quantum uncertainty, which
sets the fundamental limit on the smallest external magnetic
fields that the atom can sense. Convention