4 research outputs found
Spatio-spectral characteristics of parametric down-conversion in waveguide arrays
High dimensional quantum states are of fundamental interest for quantum
information processing. They give access to large Hilbert spaces and, in turn,
enable the encoding of quantum information on multiple modes. One method to
create such quantum states is parametric down-conversion (PDC) in waveguide
arrays (WGAs) which allows for the creation of highly entangled photon-pairs in
controlled, easily accessible spatial modes, with unique spectral properties.
In this paper we examine both theoretically and experimentally the PDC process
in a lithium niobate WGA. We measure the spatial and spectral properties of the
emitted photon-pairs, revealing strong correlations between spectral and
spatial degrees of freedom of the created photons. Our measurements show that,
in contrast to prior theoretical approaches, spectrally dependent coupling
effects have to be taken into account in the theory of PDC in WGAs. To
interpret the results, we developed a theoretical model specifically taking
into account spectrally dependent coupling effects, which further enables us to
explore the capabilities and limitations for engineering the spatial
correlations of the generated quantum states.Comment: 26 pages, 11 figure
A Soft Robotic Morphing Wing for Unmanned Underwater Vehicles
Actuators based on soft elastomers offer significant advantages to the field of robotics, providing greater adaptability, improving collision resilience, and enabling shape-morphing. Thus, soft fluidic actuators have seen an expansion in their fields of application. Closed-cycle hydraulic systems are pressure agnostic, enabling their deployment in extremely high-pressure conditions, such as deep-sea environments. However, soft actuators have not been widely adopted on unmanned underwater vehicle control surfaces for deep-sea exploration due to their unpredictable hydrodynamic behavior when camber-morphing is applied. This study presents the design and characterization of a soft wing and investigates its feasibility for integration into an underwater glider. It is found that the morphing wing enables the glider to adjust the lift-to-drag ratio to adapt to different flow conditions. At the operational angle of attack of 12.5 degrees, the lift-to-drag ratio ranges from -70% to +10% compared to a rigid version. Furthermore, it reduces the need for internal moving parts and increases maneuverability. The findings lay the groundwork for the real-world deployment of soft robotic principles capable of outperforming existing rigid systems. With the herein-described methods, soft morphing capabilities can be enabled on other vehicles.ISSN:2640-456