Title : Controlling Neutron Orbital Angular Momentum Speaker Name: Dr. Charles W. Clark Speaker Institution : NIST (JQI) Abstract : Quantized orbital angular momentum (OAM) of waves and particles offers an additional degree of freedom and topological protection from noise. OAM states of photons have been exploited in applications ranging from studies of quantum entanglement and quantum information science to 30 gigabit/second telecom multiplexing. OAM states of electron beams have been used to rotate nanoparticles and determine the chirality of crystals. OAM states of ultracold atoms are finding applications in the emerging field of atomtronics. OAM control of neutrons has not previously been achieved. We recently demonstrated OAM control of neutrons using macroscopic spiral phase plates that apply a ‘twist’ to an input neutron beam. The twisted neutron beams are analyzed with neutron interferometry. Our techniques, applied to spatially incoherent beams, demonstrate both the addition of quantum angular momenta along the direction of propagation, effected by multiple spiral phase plates, and the conservation of topological charge with respect to uniform phase fluctuations. Neutron-based studies of quantum information science, the foundations of quantum mechanics, and scattering and imaging of materials have until now been limited to three degrees of freedom: spin, path and energy. The optimization of OAM control can provide an additional quantized degree of freedom for such studies.
References:
“Controlling neutron orbital angular momentum,” C. W. Clark, et al., Nature 525, 504 (2015) “Hysteresis in a quantized superfluid atomtronic circuit,” S. Eckel, et al., Nature 506, 200 (2014)