title: Surpassing the standard quantum limit for optical imaging using nonclassical multimode light.
abstract: Using continuous wave superposition of spatial modes, we demonstrate experimentally displacement measurement of a light beam below the standard quantum limit. Multimode squeezed light is obtained by mixing a vacuum squeezed beam and a coherent beam that are spatially orthogonal. Although the resultant beam is not squeezed, it is shown to have strong internal spatial correlations. We show that the position of such a light beam can be measured using a split detector with an increased precision compared to a classical beam. This method can be used to improve the sensitivity of small displacement measurements.
authors: Laboratoire Kastler Brossel, Université Pierre et Marie Curie, case 74, 75252 Paris cedex 05, France.
authors: N
authors: N
authors: Treps
authors: U
authors: U
authors: Andersen
authors: B
authors: B
authors: Buchler
authors: P K
authors: PK
authors: Lam
authors: A
authors: A
authors: Maître
authors: H-A
authors: HA
authors: Bachor
authors: C
authors: C
authors: Fabre