We propose a quantum-enhanced metrological scheme utilizing unbalanced entangled coherent states(ECSs) generated by passing a coherent state and a coherent state superposition through an unbalanced beam splitter(BS). ...We propose a quantum-enhanced metrological scheme utilizing unbalanced entangled coherent states(ECSs) generated by passing a coherent state and a coherent state superposition through an unbalanced beam splitter(BS). We identify the optimal phase sensitivity of this scheme by maximizing the quantum Fisher information(QFI) with respect to the BS transmission ratio. Our scheme outperforms the conventional scheme with a balanced BS, particularly in the presence of single-mode photon loss. Notably, our scheme retains quantum advantage in phase sensitivity in the limit of high photon intensity, where the balanced scheme offers no advantage over the classical strategy.展开更多
One of the main obstacles for quantum-enhanced metrology is that the estimation accuracy enhanced by non-classical states is likely to be obliterated by noises. Here, we consider a scenario of phase estimation sufferi...One of the main obstacles for quantum-enhanced metrology is that the estimation accuracy enhanced by non-classical states is likely to be obliterated by noises. Here, we consider a scenario of phase estimation suffering from pure dephasing noise which is taken into account after the phase parameter being imprinted, and propose a scheme to effectively protect the quantum enhancement from both correlated and uncorrelated dephasing sources by performing a rotation operation prior to the noise. By invoking the Fisher information approach, we strictly prove that a π/2 rotation is the ideal one which can completely resist the influence of the phase noise for all real symmetric pure states and the optimal measurement approaching the ultimate sensitivity set by quantum Cramér–Rao bound is presented.Additionally, we numerically study the availability of the scheme with arbitrary angle rotation for different probe states and show that our scheme will still robust for general symmetric pure states even with non-ideal rotation operation.展开更多
Performing homodyne detection at a single output port of a squeezed-state light interferometer and then separating the measurement quadrature into two intervals can realize super-resolving and super-sensitive phase me...Performing homodyne detection at a single output port of a squeezed-state light interferometer and then separating the measurement quadrature into two intervals can realize super-resolving and super-sensitive phase measurements,which is equivalent to a binary-outcome measurement.Obviously,the single-port homodyne detection may lose almost part of the phase information,reducing the estimation precision.Here,we propose a data-processing technique over the doubleport homodyne detection,where the two-dimensional measurement quadrature(p1,p2)has been divided into two regions.With such a binary-outcome measurement,we estimate the phase shift accumulated in the interferometer by inverting the output signal.By analyzing the full width at half maximum of the signal and the phase sensitivity,we show that both the resolution and the achievable sensitivity are better than that of the previous binary-outcome scheme.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 12005106)support from the National Natural Science Foundation of China (Grant No. 11974189)+1 种基金support from the National Natural Science Foundation of China (Grant No. 12175106)the Postgraduate Research and Practice Innovation Program of Jiangsu Province (Grant No. JSCX23-0260)。
文摘We propose a quantum-enhanced metrological scheme utilizing unbalanced entangled coherent states(ECSs) generated by passing a coherent state and a coherent state superposition through an unbalanced beam splitter(BS). We identify the optimal phase sensitivity of this scheme by maximizing the quantum Fisher information(QFI) with respect to the BS transmission ratio. Our scheme outperforms the conventional scheme with a balanced BS, particularly in the presence of single-mode photon loss. Notably, our scheme retains quantum advantage in phase sensitivity in the limit of high photon intensity, where the balanced scheme offers no advantage over the classical strategy.
基金Support by the National Natural Science Foundation of China under Grant No.11475146
文摘One of the main obstacles for quantum-enhanced metrology is that the estimation accuracy enhanced by non-classical states is likely to be obliterated by noises. Here, we consider a scenario of phase estimation suffering from pure dephasing noise which is taken into account after the phase parameter being imprinted, and propose a scheme to effectively protect the quantum enhancement from both correlated and uncorrelated dephasing sources by performing a rotation operation prior to the noise. By invoking the Fisher information approach, we strictly prove that a π/2 rotation is the ideal one which can completely resist the influence of the phase noise for all real symmetric pure states and the optimal measurement approaching the ultimate sensitivity set by quantum Cramér–Rao bound is presented.Additionally, we numerically study the availability of the scheme with arbitrary angle rotation for different probe states and show that our scheme will still robust for general symmetric pure states even with non-ideal rotation operation.
基金the Science Foundation of Zhejiang Sci-Tech University,grant number 18062145-Ythe National Natural Science Foundation of China(NSFC)grant number12075209.
文摘Performing homodyne detection at a single output port of a squeezed-state light interferometer and then separating the measurement quadrature into two intervals can realize super-resolving and super-sensitive phase measurements,which is equivalent to a binary-outcome measurement.Obviously,the single-port homodyne detection may lose almost part of the phase information,reducing the estimation precision.Here,we propose a data-processing technique over the doubleport homodyne detection,where the two-dimensional measurement quadrature(p1,p2)has been divided into two regions.With such a binary-outcome measurement,we estimate the phase shift accumulated in the interferometer by inverting the output signal.By analyzing the full width at half maximum of the signal and the phase sensitivity,we show that both the resolution and the achievable sensitivity are better than that of the previous binary-outcome scheme.
