Sensing with neutral atoms.

R. N. Compton

David H. Meyer

This work encompasses two projects employing coherent probing of neutral rubidium atom vapors for sensing applications: 1) observing and characterizing new ``twists'' within Nonlinear Magneto-Optical Rotation (NMOR) signals in laser-cooled atoms. Using these features an in-situ, multi-directional characterization of magnetic fields and gradients at the sub-mG (and mG/mm) level in a compact cold-atom system is demonstrated; 2) high-bandwidth, phase-sensitive electrometry via Electromagnetically Induced Transparency (EIT) with a warm vapor of Rydberg atoms is employed as a digital communication receiver of free-space, modulated RF carrier electric fields. Channel capacities in excess of 10 Mbit/s are measured. Performance limitations due to EIT probing and fundamental quantum noise are explored in detail.

Daniel K. Ruttley, Tom R. Hepworth, Juan M. García-Garrido +4 more

Arrays of trapped neutral atoms and polar molecules have separately emerged as powerful and complementary platforms for quantum science. Neutral atoms enable fast, programmable interactions through excitation to Rydberg states, whereas polar molecules possess long-lived rotational states that are attractive for quantum memories and qudits. Combining these platforms would create new possibilities, but requires a coherent interface between individual atoms and molecules, which so far has not been realised. Here, we establish such an interface between a single neutral atom and a single polar molecule. By tuning atomic and molecular transitions into resonance, we realise strong state-dependent dipolar interactions at micrometre separations in an optical tweezer platform with single-particle control. We exploit this interface to perform quantum operations between the two particles, demonstrating atom-mediated readout of a molecular qubit, coherent spin exchange, and entanglement using a blockade-based controlled-NOT operation. These results establish a new hybrid quantum platform at the intersection of atomic and molecular physics, in which long-lived molecular quantum information can be rapidly mapped onto an atom for readout or onward coherent transfer. The platform provides a route to hybrid quantum processors utilising atom-mediated readout and entanglement of molecular qubits, mixed-species quantum simulators of dipolar systems, and macroscopic entangled molecular states for quantum-enhanced metrology and precision sensing.