title: Quantum uncertainty in the beam width of spatial optical modes.
abstract: We theoretically investigate the quantum uncertainty in the beam width of transverse optical modes and, for this purpose, define a corresponding quantum operator. Single mode states are studied as well as multimode states with small quantum noise. General relations are derived, and specific examples of different modes and quantum states are examined. For the multimode case, we show that the quantum uncertainty in the beam width can be completely attributed to the amplitude quadrature uncertainty of one specific mode, which is uniquely determined by the field under investigation. This discovery provides us with a strategy for the reduction of the beam width noise by an appropriate choice of the quantum state.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Chille
authors.forename: Peter
authors.initials: P
authors.lastname: Banzer
authors.forename: Andrea
authors.initials: A
authors.lastname: Aiello
authors.forename: Gerd
authors.initials: G
authors.lastname: Leuchs
authors.forename: Christoph
authors.initials: C
authors.lastname: Marquardt
authors.forename: Nicolas
authors.initials: N
authors.lastname: Treps
authors.forename: Claude
authors.initials: C
authors.lastname: Fabre