The phase sensitivity of an SU(1,1) interferometer with coherent and squeezed-vacuum light

Abstract

We theoretically study the phase sensitivity of an SU(1,1) interferometer with a coherent state in one input port and a squeezed-vacuum state in the other input port using the method of homodyne detection. In this interferometer, beam splitting and recombination are generated by the parametric amplifiers instead of the beam splitters. Compared with the traditional Mach-Zehnder interferometer, the phase sensitivity of this interferometer can be improved due to the amplification process of the parametric amplifiers. Combined with the squeezed state input, the sensitivity can be improved further due to the noise reduction. The phase sensitivity of our scheme can approach the Heisenberg limit and the associated optimal condition is analyzed. The scheme can be implemented with current experimental technology.

Phase sensitivity at the Heisenberg limit in an SU(1,1) interferometer via parity detection

“…Furthermore, as shown in Ref. [12], these input states in an SU(1,1) interferometer are 1) interferometer. Two OPAs take the place of two beam splitters in the traditional Mach-Zehnder interferometer.…”

“…Meanwhile the homodyne detection is always bad due to a constant measurement signal X 2 = 0. With one coherent input |α 0 ⊗|0 or coherent mixed with squeezed-vacuum input |α 0 ⊗ |0, ξ , parity detection has a slightly better phase sensitivity than homodyne detection [12], meanwhile intensity detection is not exactly known (NEK) due to divergence at the optimal point. In this point of view, parity detection is more suitable than homodyne detection.…”

“…Here, we still consider coherent and squeezed vacuum input light as in our previous work [12] which focused on homodyne detection on SU(1,1) interferometers. With the coherent state and squeezed vacuum state as the input, one can reduce the required intensity of input coherent states and obtain the same measurement sensitivity, which can eliminate the disadvantages due to using stronger coherent states.…”

Optimal phase measurements with bright- and vacuum-seeded SU(1,1) interferometers

“…The scheme in Fig. 2b is the conventional SU(1,1) interferometer with homodyne detection [19,25]. We begin, however, by considering the experiment shown in Fig.…”

“…In Sec. III, we discuss the sensitivity for the conventional SU(1,1) system using optical intensity detection, which has been discussed elsewhere [6,[13][14][15][16][17][18][19][20]. We show that intensity detection is the optimal detection scheme for the vacuum-seeded case, but is not optimal in the bright-seeded case.…”