Rydberg atoms have attracted significant interest recently as electric field sensors. In order to assess potential applications, detailed understanding of relevant figures of merit is necessary, particularly in relation to other, more mature, sensor technologies. Here we present a quantitative analysis of the Rydberg sensor's sensitivity to oscillating electric fields with frequencies between 1 kHz and 1 THz. Sensitivity is calculated using a combination of analytical and semi-classical Floquet models. Using these models, optimal sensitivity at arbitrary field frequency is determined. We validate the numeric Floquet model via experimental Rydberg sensor measurements over a range of 1-20 GHz. Using analytical models, we compare with two prominent electric field sensor technologies: electro-optic crystals and dipole antenna-coupled passive electronics.

We introduce multiplexed atom-cavity quantum electrodynamics with an atomic ensemble coupled to a single optical cavity mode. Multiple Raman dressing beams establish cavity-coupled spinwave excitations with distinctive spatial profiles. Experimentally, we demonstrate the concept by observing spin-wave vacuum Rabi splittings, selective superradiance, and interference in the cavitymediated interactions of two spin waves. We highlight that the current experimental configuration allows rapid, interchangeable cavity-coupling to 4 profiles with an overlap parameter of less than 10%, enough to demonstrate, for example, a quantum repeater network simulation in the cavity. With further improvements to the optical multiplexing setup, we infer the ability to access more than 10 3 independent spin-wave profiles.Significant resources are now being devoted to develop intermediate scale quantum systems with tens or hundreds of quantum bits, tunable interactions, and independent control of each element. Ion traps [1], superconducting circuits [2], tweezer arrays of neutral atoms [3], and other systems have made exciting recent advances, but scaling precise quantum dynamics from few-body to many-body remains as a primary challenge in quantum science.Instead of building up qubit-by-qubit, like the aforementioned platforms, here we focus on a system where quantum information is stored as patterns or images inside a single cavity-coupled atomic ensemble containing up to 10 6 atoms. This scalability more closely resembles, for example, that of a neural network, where data is stored and manipulated as patterns and images rather than binary bits [4][5][6][7].In this Letter, we introduce an apparatus that allows creation of multiple spin-wave excitations with unique spatial profiles. The spin waves are all collectively enhanced to emit into a single TEM00 cavity mode, and cavity coupling of each spin wave is dynamically controlled using a corresponding Raman dressing beam, generated by a two-dimensional acousto-optic deflector. Experimentally, we first observe strong spin wave/cavity interactions by measuring a dressed-state vacuum Rabi splitting (VRS) associated with the spin-wave Raman transition. Second, we discuss how spin waves are protected from cross-talk through collective dephasing, and demonstrate a high degree of distinguishability by observing selective superradiance over the continuum of spin-wave profiles. Finally, we observe interference as two spin-waves simultaneously interact with the cavity mode.As a multiplexed atom-cavity interface [8], our system may form the building block of a scalable quantum repeater [9]. Alternatively, this approach opens an elegant avenue to demonstrate a local bosonic quantum network for efficiently simulating many-body physics [10-12], generating samples from exponentially complex wave functions, or performing entanglement-enhanced or error-corrected quantum sensing. In the future, our multiplexed atom-cavity system may be combined with nonlinear cavity-mediated interactions or quantum nond...

We present a multiplexed quantum repeater protocol based on an ensemble of laser-cooled and trapped rubidium atoms inside an optical ring cavity. We have already demonstrated strong collective coupling in such a system and have constructed a multiplexing apparatus based on a two-dimensional acousto-optical deflector. Here, we show how this system could enable a multiplexed quantum repeater using collective excitations with non-trivial spatial phase profiles (spinwaves). Calculated entanglement generation rates over long distances reveal that such a multiplexed ensemble-cavity platform is a promising route towards long distance quantum entanglement and networking.

We experimentally and theoretically evaluate the performance of a quantum sensor based on Rydberg atoms across the entire radio-frequency spectrum from DC to 1 THz and make fundamental comparisons with other sensor types.