Abstract: A rotorcraft rotor head has: (i) two or more rotor blades attached to rotate about a rotor axis, and pivot through a flapping and/or teetering hinge, and having a pitch angle; (ii) pitch angle changing means for collectively changing said pitch angle; (iii) centrifugal pitch stop mechanism having an activation point and comprising one or more centrifugal plates; and (iv) control means for providing a control input to said pitch angle changing means; wherein said centrifugal pitch stop mechanism is configured to attain an activated state and to interact with said pitch angle changing means; wherein said activated state is attained when the rotational speed of said rotor blades is greater than said activation point and when a control input is provided by said control means; and wherein said activation point is less than the minimum rotational speed of the rotor blades that is required for flying the rotorcraft.

Abstract: The present invention relates to the formation of electron spin EPR pairs and manipulation of such entangled electrons. The invention comprises a static quantum dot located part way along a quantum wire with means for adjusting the confining potential of the quantum dot. The quantum wire may for instance be formed by gate electrode (4, 6) with the quantum dot formed by a further gate electrode (8). The invention also comprises means for generating a electrostatic wave propagating along the wire, such as a surface acoustic wave transducer (10). In use a pair of electrons may be loaded into the static quantum dot and allowed to relax to a singlet ground state, in which the electrons are spin entangled. The propagating electrostatic wave acts as a series of quantum dots moving along the quantum wire.

Abstract: The present invention relates to the formation of electron spin EPR pairs and manipulation of such entangled electrons. The invention comprises a static quantum dot located part way along a quantum wire with means for adjusting the confining potential of the quantum dot. The quantum wire may for instance be formed by gate electrode (4, 6) with the quantum dot formed by a further gate electrode (8). The invention also comprises means for generating a electrostatic wave propagating along the wire, such as a surface acoustic wave transducer (10). In use a pair of electrons may be loaded into the static quantum dot and allowed to relax to a singlet ground state, in which the electrons are spin entangled. The propagating electrostatic wave acts as a series of quantum dots moving along the quantum wire.