Continuous Accumulation of Millions of Cold Atoms Advances Quantum Technologies

The pursuit of continuously operating atom-light interfaces represents a crucial step towards realising practical, steady-state sensors and efficient quantum processors, and a team led by Edward Gheorghita, Sebastian Wald, and Andrea Pupić from the Institute of Science and Technology Austria (ISTA), alongside Onur Hosten and colleagues, now demonstrates a method for achieving continuous accumulation of cold atoms within an optical cavity. This breakthrough centres on a clever manipulation of light shifts, creating spatially varying cooling parameters that efficiently capture and accumulate atoms within a specific cavity mode, effectively funnelling a continuous flux of rubidium atoms from a source cell into a cooled, steady-state ensemble. The researchers characterise this continuously maintained collection of millions of atoms and its strong interaction with the cavity field, establishing a pathway towards continuously operated cavity-QED systems and enabling the development of long-duration atomic and hybrid sensors with unprecedented stability. This achievement overcomes the limitations of previous time-sequenced methods, paving the way for a new generation of quantum technologies.

Continuous Atom Trapping in Optical Cavities Scientists engineered a novel method for continuously accumulating cold atoms within an optical cavity, a key advancement for developing steady-state quantum sensors and efficient quantum processors. This allows them to build up a stable, high-density population of cold atoms within the cavity, exceeding the capabilities of conventional atomic traps. Characterization of the accumulated atoms reveals a significant increase in optical density compared to free-space atomic beams, demonstrating the potential of this technique for creating robust and efficient quantum devices.

Continuous Atom Accumulation Within Optical Cavity Researchers developed a new technique for continuously accumulating and cooling atoms directly within an optical cavity, overcoming limitations of previous time-sequenced approaches. The study pioneered a method utilizing a two-tone laser trap at 1560 and 1527 nanometers to simultaneously achieve magneto-optical trapping, dipole trapping, and optical molasses. This configuration maintains a steady-state population of millions of atoms at temperatures reaching 3 microkelvin. The experimental setup centers around an in-vacuum traveling-wave optical cavity constructed with mirrors optimized for operation near both 780 and 1560 nanometers. These mirrors exhibit high reflectivity for certain polarization modes, while maintaining lower reflectivity for others, enabling a dual-wavelength configuration that leverages near-resonant interaction with the atoms and a far off-resonant dipole trap. A crucial aspect of the method involves manipulating light shifts to create spatially varying cooling parameters, efficiently capturing and accumulating atoms within the cavity. Researchers employed a sophisticated optical system to precisely control and deliver the laser beams, sustaining a steady-state ensemble of atoms within the optical cavity, opening avenues for continuous-wave atomic clocks, steady-state hybrid cold atom-optomechanical quantum systems, and efficient reloading of atoms into quantum processors for large-scale quantum computations.

Persistent Atomic Ensemble Trapped Within Optical Cavity Scientists have achieved a breakthrough in continuously operating atom-light interfaces, a key requirement for advanced sensors and processors. The research demonstrates the continuous accumulation of sub-Doppler-cooled rubidium atoms within a shallow intracavity dipole trap, establishing a stable and persistent atomic ensemble. This was accomplished through a novel light-shift manipulation technique that creates spatially varying cooling parameters, efficiently capturing and retaining atoms within the cavity mode without requiring time-sequenced operation.

The team measured a continuously maintained ensemble containing millions of atoms, demonstrating their collective coupling to the cavity field, essential for realizing continuously operated cavity-QED systems and enabling long-duration atomic and hybrid sensors. Crucially, the light-shift compensation allows for seamless implementation of in-trap molasses cooling, optical pumping for internal state preparation, and state-dependent removal of atoms using a resonant push beam, enabling efficient state purification and background measurements. Experiments reveal that this new operational regime allows laser cooling, optical trapping, and cavity coupling to coexist seamlessly in a steady state. Because the method relies on tunable optical parameters and shallow dipole traps, it is readily adaptable to various atomic systems, opening new possibilities for continuous atomic quantum sensors, hybrid quantum platforms, and continuously reloaded atomic quantum processors, representing a significant step towards practical quantum technologies.

Continuous Atomic Accumulation in Optical Cavities Scientists have demonstrated the continuous accumulation of laser-cooled atoms within a shallow optical trap inside a cavity, representing a significant step towards continuously operating quantum systems and sensors. By carefully manipulating the light interacting with the atoms, the team created spatially varying cooling conditions that efficiently capture and retain atoms sourced from a magneto-optical trap. This technique allows for the steady-state maintenance of millions of atoms, a substantial improvement over previous methods requiring time-sequenced operation. The resulting ensemble exhibits strong collective coupling to the cavity field, paving the way for sustained interactions crucial for advanced quantum technologies. The research establishes a method for maintaining a dense atomic ensemble without interruption, achieved through the exploitation of natural sub-Doppler cooling mechanisms. Experiments reveal that the number of accumulated atoms increases sharply with specific light manipulation parameters, reaching over a million atoms after a relatively short accumulation period.

The team characterized the cooling process using time-of-flight measurements, confirming the effectiveness of the technique in achieving and sustaining low atomic temperatures. While the current work focuses on rubidium atoms, the principles demonstrated are broadly applicable to other atomic species. 👉 More information 🗞 Continuous Accumulation of Cold Atoms in an Optical Cavity 🧠 ArXiv: https://arxiv.org/abs/2512.14528 Tags: