title: Anomalous amplification of a homodyne signal via almost-balanced weak values.
abstract: We propose precision measurements of ultra-small angular velocities of a mirror within a modified Sagnac interferometer, where the counter-propagating beams are spatially separated, using the recently proposed technique of almost-balanced weak values amplification (ABWV) [Phys. Rev. Lett.116, 100803 (2016)PRLTAO0031-900710.1103/PhysRevLett.116.100803]. The separation between the two beams provides additional amplification with respect to using collinear beams in a Sagnac interferometer. Within the same setup, the weak-value amplification technique is also performed for comparison. Much higher amplification factors can be obtained using the almost-balanced weak values technique, with the best one achieved in our experiments being as high as 1.2×107. In addition, the amplification factor monotonically increases with decreasing of the post-selection phase for the ABWV case in our experiments, which is not the case for weak-value amplification (WVA) at small post-selection phases. Both techniques consist of measuring the angular velocity. The sensitivity of the ABWV technique is ∼38  nrad/s per averaged pulse for a repetition rate of 1 Hz and ∼33  nrad/s per averaged pulse for the WVA technique.
authors.forename: Wei-Tao
authors.initials: WT
authors.lastname: Liu
authors.forename: Julián
authors.initials: J
authors.lastname: Martínez-Rincón
authors.forename: Gerardo I
authors.initials: GI
authors.lastname: Viza
authors.forename: John C
authors.initials: JC
authors.lastname: Howell