Microwave-field quantum metrology with error correction enabled by Rydberg atoms

Abstract: Quantum sensing and metrology present one of the most promising near-term applications in the field of quantum technologies, with quantum sensors enabling unprecedented precision in measurements of electric, magnetic or gravitational fields and displacements. Experimental loss at the detection stage remains one of the key obstacles to achieve a truly quantum advantage in many practical scenarios. Here we combine capabilities of Rydberg atoms to both sense external fields and to be used for quantum information processing to largely overcome the issue of detection losses. While using the large dipole moments of Rydberg atoms in an ensemble to achieve a $39\ \mathrm{nV}/\mathrm{cm}\sqrt{\mathrm{Hz}}$ sensitivity we employ the inter-atomic dipolar interactions to execute an error-correction protocol, that protects sensing information against conventional losses at the detection stage. Counterintuitively, the idea of the protocol is based on introduction of additional non-linear lossy quantum channel, which results in enhancement of Fisher information by a factor of 3.3. The presented results open up a path towards broader usage of quantum-information-inspired error correction in practical quantum metrology and communication, without the need for a general-purpose quantum computer.