The creation of exotic quantum states that allow atomic sensors to operate beyond the Standard Quantum Limit (SQL) and near (or at) the Heisenberg Limit for many-particle systems has been a long-sought goal in Quantum Metrology. Gaussian Spin Squeezed States have been used to overcome the SQL in atomic sensors but offer limited quantum metrological advantages. To approach the Heisenberg Limit, Non-Gaussian Entangled States (NGES) with larger entanglement have to be engineered. However, the fragility of highly entangled states against decoherence and single-particle state resolution requirements have made difficult their experimental realization and application to atomic sensors with today’s technology.
We present here the implementation of a robust Signal Amplification through Time-reversal INteraction (SATIN) protocol, that allows for the generation of NGESs and the efficient use of their quantum resource. We demonstrate an angular resolution of 12.8 dB beyond the SQL for a system of 370 ytterbium-171 atoms (and 12.8 dB away from the Heisenberg limit), Heisenberg scaling with atom number, and a record-breaking phase-sensitive measurement of 11.8 dB beyond the SQL. We plan to transfer these NGESs to the optical-clock transition of ytterbium-171.