Spatial squeezing

Supported by the Lundbeck Foundation

Spatial squeezing

The simplest spatial mode that can carry orbital angular momentum (OAM) is the first order Laguerre-Gaussian (LG) mode, which produces either a left-handed or right-handed corkscrew-like phase front and a ring-like intensity profile. In this work we produce continuous variables quadrature entanglement between the two first-order LG modes and thereby demonstrating a new type of entanglement from non-degenerate optical parametric oscillators (OPOs). The entanglement is manifested in the squeezing of the rotated modes in the Hermite-Gauss (HG) basis, measured with a specially tailored local oscillator.

By changing the OPO cavity resonance frequency it is possible to generate the two first order Hermite-Gauss (HG) modes simultaneously due to their frequency degeneracy (stemming from their identical Gouy phase shifts). This means that the down-converted signal and idler photons are produced in two distinct orthogonal spatial modes (the OAM modes, LG+1 and LG-1), and thus creates quadrature entanglement between these two modes similarly to the production of entanglement between polarization.

For more details about this work please check http://xxx.lanl.gov/abs/0901.2783

Ref: M. Lassen, G. Leuchs and U.L. Andersen ArXiv: 0901.2783