TY - JOUR

T1 - Position, spin, and orbital angular momentum of a relativistic electron

AU - Bliokh, Konstantin Y.

AU - Dennis, Mark R.

AU - Nori, Franco

N1 - Publisher Copyright:
© 2017 American Physical Society.

PY - 2017/8/28

Y1 - 2017/8/28

N2 - Motivated by recent interest in relativistic electron vortex states, we revisit the spin and orbital angular momentum properties of Dirac electrons. These are uniquely determined by the choice of the position operator for a relativistic electron. We consider two main approaches discussed in the literature: (i) the projection of operators onto the positive-energy subspace, which removes the Zitterbewegung effects and correctly describes spin-orbit interaction effects, and (ii) the use of Newton-Wigner-Foldy-Wouthuysen operators based on the inverse Foldy-Wouthuysen transformation. We argue that the first approach [previously described in application to Dirac vortex beams in K. Y. Bliokh, Phys. Rev. Lett. 107, 174802 (2011)PRLTAO0031-900710.1103/PhysRevLett.107.174802] has a more natural physical interpretation, including spin-orbit interactions and a nonsingular zero-mass limit, than the second one [S. M. Barnett, Phys. Rev. Lett. 118, 114802 (2017)PRLTAO0031-900710.1103/PhysRevLett.118.114802].

AB - Motivated by recent interest in relativistic electron vortex states, we revisit the spin and orbital angular momentum properties of Dirac electrons. These are uniquely determined by the choice of the position operator for a relativistic electron. We consider two main approaches discussed in the literature: (i) the projection of operators onto the positive-energy subspace, which removes the Zitterbewegung effects and correctly describes spin-orbit interaction effects, and (ii) the use of Newton-Wigner-Foldy-Wouthuysen operators based on the inverse Foldy-Wouthuysen transformation. We argue that the first approach [previously described in application to Dirac vortex beams in K. Y. Bliokh, Phys. Rev. Lett. 107, 174802 (2011)PRLTAO0031-900710.1103/PhysRevLett.107.174802] has a more natural physical interpretation, including spin-orbit interactions and a nonsingular zero-mass limit, than the second one [S. M. Barnett, Phys. Rev. Lett. 118, 114802 (2017)PRLTAO0031-900710.1103/PhysRevLett.118.114802].

UR - http://www.scopus.com/inward/record.url?scp=85028689437&partnerID=8YFLogxK

U2 - 10.1103/PhysRevA.96.023622

DO - 10.1103/PhysRevA.96.023622

M3 - Article

SN - 2469-9926

VL - 96

JO - Physical Review A

JF - Physical Review A

IS - 2

M1 - 023622

ER -