Practical quantum optical metrology with a 7-fold enhancement
Paul A. Knott, Anthony Hayes, Timothy J Proctor, Jacob Dunningham · arXiv (Cornell University) · 2015
School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom(Dated: May 18, 2015)Quantum metrology exploits quantum correlations to make precise measurements with limitedparticle numbers. By maximising the inter- and intra- mode correlations in an optical interferometer,we nd a state that combines squeezing and entanglement to give a 7-fold enhancement in thequantum Fisher information (QFI) over the NOON state for low photon numbers. Motivated bypracticality we then look at the squeezed cat state, which has recently been made experimentally, andshows further precision gains, including a 3-fold improvement in the QFI over the optimal Gaussianstate. We present a simple measurement scheme that saturates the QFI, and then simulate thisscheme to con rm its e ectiveness. Finally, we show that for small photon numbers the squeezedcat state continues to give an advantage even for signi cant losses, allowing us to conclude that thesqueezed cat state can give a signi cant precision enhancement in optical quantum metrology inrealistic conditions.