We theoretically study the phase sensitivity of an SU(1,1) interferometer with a thermal state and a squeezed vacuum state as inputs and parity detection as the measurement. We find that the phase sensitivity can beat the shot-noise limit and approaches the Heisenberg limit, with increasing input photon number, in an ideal situation. We also consider the e ect of various noises, including photon loss, dark counts, and thermal photon noise. Our results show that the phase sensitivity is below the shot-noise limit with photon loss and dark counts, but cannot beat the shot-noise limit in the presence of thermal noise.
Publication Source (Journal or Book title)
Ma, X., You, C., Adhikari, S., Matekole, E., Glasser, R., Lee, H., & Dowling, J. (2018). Sub-shot-noise-limited phase estimation via SU(1,1) interferometer with thermal states. Optics Express, 26 (14), 18492-18504. https://doi.org/10.1364/OE.26.018492