Phase supersensitivity in an unbalanced SU(1,1) interferometer
Friday 12 May 2017
to 11:00 at
Maria V Chekhova (Erlangen/Moscow)
A nonlinear interferometer, generally, is a sequence of two nonlinear effects occurring coherently. We investigate the properties of such an interferometer consisting of two unseeded high-gain degenerate optical parametric amplifiers (DOPAs). This configuration is known in the literature as an SU(1,1) interferometer and it enables achieving the Heisenberg limit in phase sensitivity. Moreover, by making the two DOPAs unbalanced, the parametric gain of the second one considerably exceeding the one of the first one, one can overcome the detection losses .
In our experiment, we demonstrate a phase sensitivity overcoming the shot noise limit by more than 2dB, with the number of photons in the interferometer being between 1 and 10. We show that the phase sensitivity is considerably improved by increasing the parametric gain of the second DOPA.
The observed tolerance to detection losses will be very important for phase measurements, including the ones related to gravitational-wave detection, in ‘difficult’ spectral ranges where detection is inefficient.