Double-port measurements for robust quantum optical metrology

It has been proposed and demonstrated that path-entangled Fock states (PEFSs) are robust against photon loss over NOON states [S. D. Huver et al., Phys. Rev. A 78, 063828 (2008)]. However, the demonstration was based on a measurement scheme which was yet to be implemented in experiments. In this work, we quantitatively illustrate the advantage of PEFSs over NOON states in the presence of photon losses by analytically calculating the quantum Fisher information. To realize such an advantage in practice, we then investigate the achievable sensitivities by employing three types of feasible measurements: parity, photon-number-resolving, and homodyne measurements. We here apply a double-port measurement strategy where the photons at each output port of the interferometer are simultaneously detected with the aforementioned types of measurements.

Automated summary

The study demonstrates the advantage of path-entangled Fock states (PEFSs) over NOON states in the presence of photon losses by analytically calculating the quantum Fisher information. Three types of feasible measurements are investigated to achieve this advantage: parity, photon-number-resolving, and homodyne measurements. The researchers apply a double-port measurement strategy to simultaneously detect photons at each output port of the interferometer with different measurement types.