Spatial Multiplexing of Squeezed Light by Coherence Diffusion

Abstract

Spatially splitting nonclassical light beams is in principle prohibited due to noise contamination during beam splitting. We propose a platform based on thermal motion of atoms to realize spatial multiplexing of squeezed light. Light channels of separate spatial modes in an anti-relaxation coated vapor cell share the same long-lived atomic coherence jointly created by all channels through the coherent diffusion of atoms which in turn enhances individual channel's nonlinear process responsible for light squeezing. Consequently, it behaves as squeezed light in one optical channel transferring to other distant channels even with laser powers below the threshold for squeezed light generation. An array of squeezed light beams was created with low laser power ∼ mW. This approach holds great promise for applications in multi-node quantum network and quantum enhanced technologies such as quantum imaging and sensing. * Electronic address: heng.shen@physics.ox.ac.uk † Electronic address: yxiao@fudan.edu.cn

Quantum Dynamics of Collective Spin States in a Thermal Gas

“…( 11)] and is thus applicable to non-classical experiments done in that regime [32]. Our model can also describe other space-dependent phenomena, such as the dynamics in the presence of nonuniform driving fields [29].…”

“…Since thermal motion is inherent to gas-phase systems, our model could be beneficial to many studies of non-classical spin gasses and particularly to warm alkali vapors. One such example is a recent demonstration of transfer of quantum correlations by the diffusion of alkali atoms between different spatial regions [29]. Other examples involve a single active region, e.g., when spin squeezing is performed using a small probe beam over a long probing time, with the goal of coupling efficiently to the uniform diffusion mode in a coated cell [17,21].…”

“…Non-classical phenomena involving collective spin states, such as transfer of quantum correlations between nonoverlapping light beams by atomic motion [29][30][31], call for a quantum description of the thermal motion. For spinexchange collisions, which are an outcome of thermal motion, such a quantum description has received much recent attention [32][33][34][35][36][37][38].…”

Strong coupling of alkali spins to noble-gas spins with hour-long coherence time

“…Remarkably, the quantum description persists even for gaseous ensembles undergoing rapid diffusion [23,24] and for overlapping ensembles that interact via atomic collisions [21,[25][26][27]. The collective state of alkali spins can be addressed and coherently controlled by optical means [28][29][30].…”

Topological atomic spinwave lattices by dissipative couplings

“…Our scheme can be extended to larger arrays with designed configurations, or combined with synthetic dimensions encoded in the internal atomic levels. Moreover, the tunable non-Hermitian couplings can be combined with the controllability over atomic spins by multilevel and nonlinear atom-light interactions in each channel [34]. With these, the present platform is unique as it integrates the rich degrees of freedom in engineering non-Hermitian arrays with the accessibility of quantum physics associated with coherent atom-light interactions.…”