Quantum multiparameter estimation has important applications in quantum imaging and distributed sensor networks. In this work, we propose a displacement-enhanced interferometric scheme for the simultaneous estimation of two independent phases, based on a conventional three-mode linear interferometer supplemented with three displacement operations (DOs). We show that the per-photon quantum Cramér-Rao bound (QCRB) can be minimized by optimizing the amplitudes and arguments of the DOs and by enhancing the entanglement of the input signal states. Squeezed probe states yield improved phase-estimation precision due to their reduced noise, and this advantage can be further amplified by the DOs, especially for the input two-mode squeezed vacuum state. In the ideal case, optimal per-photon QCRB can be achieved by stabilizing the DO parameters for most signal states, except for single-mode squeezed inputs. When photon loss is included, the optimal DO settings for two coherent-state inputs remain insensitive to loss, whereas for other signal states, the DO parameters must be tuned within a finite range, increasing the experimental complexity. Our results provide useful guidance for practical quantum-enhanced multiparameter estimation.

Close

PrevNext

View figure in article

• Quantum metrology