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Atomic Quantum Metrology

Final Report Summary - AQUMET (Atomic Quantum Metrology)

The project AQUMET developed methods by which quantum effects such as entanglement can improve the sensitivity of atomic instruments, with a special focus on atomic sensors for magnetic fields. The project produced several new entangled states of matter, including a "macroscopic singlet state" containing a record 500.000 entangled atoms, and a "planar squeezed state" that is useful for sensing both the strength of the magnetic field and the physical environment, as is done in magnetic resonance imaging. The project demonstrated the first use of entangled atoms to improve sensitivity when measuring slow magnetic fields, as in non-destructive techniques for measuring heart and brain activity. The project also applied entangled photons to improve the sensitivity of atomic instruments, including the first observation of individual entangled photons inside a macroscopic entangled state, demonstration that entangled photons can make more delicate measurements on fragile systems, and the first measurements with entangled photons on high-density atomic sensors. As a spin-off of the main activity, AQUMET also developed the quantum random number generators used in the three "loophole-free Bell tests" of 2015.