Super-sensitive phase estimation with coherent boosted light using parity measurements<xref rid="cpb_27_1_014203_fn1" ref-type="fn">*</xref> <fn id="cpb_27_1_014203_fn1"> <label>*</label> <p>Project supported by the National Natural Science Foundation of China (Grant No. 11665010), the Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, China (Grant No. QSQC1414), and the Scientific Research Fund of Hunan Provincial Education Department, China (Grant No. 17B055).</p> </fn>

Super-sensitive phase estimation with coherent boosted light using parity measurements* *

Project supported by the National Natural Science Foundation of China (Grant No. 11665010), the Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, China (Grant No. QSQC1414), and the Scientific Research Fund of Hunan Provincial Education Department, China (Grant No. 17B055).

Xu Lan^{1, 2, 3}, Tan Qing-Shou^{1, †}

(color online) (a) Schematic diagram of the passive and active hybrid interferometry, which is formed by adding an OPA before an MZI. This setup is sensitive to the differential phase shift ϕ_d = φ_a − φ_b, and the information is extracted by a parity detection on one of the second beam splitter’s outputs. (b) Schematic drawing of an ideal SU(1,1) interferometer. The beam splitters of the MZI have been replaced by OPAs. There is a π phase shift between the two OPAs. Different from the setup in panel (a), the SU(1,1) interferometer is sensitive to the sum phase shift ϕ_s = φ_a + φ_b and the total photon intensity measurement is taken on the second OPA’s outputs.