We theoretically analyze the phase sensitivity of the Induced-Coherence Interferometer, including the case where the sensitivity is "boosted" into the bright input regime with coherent-light seeding. We find scaling which reaches below the shot noise limit, even when seeding the spatial mode which does not interact with the sample - or when seeding the undetected mode. Furthermore, the setup allows use of subtracted intensity measurements, instead of direct or homodyne measurements - a significant practical advantage. Bright, super-sensitive phase estimation of an object with different light fields for interaction and detection is possible.We theoretically analyze the phase sensitivity of the Induced-Coherence Interferometer, including the case where the sensitivity is "boosted" into the bright input regime with coherent-light seeding. We find scaling which reaches below the shot noise limit, even when seeding the spatial mode which does not interact with the sample - or when seeding the undetected mode. Furthermore, the setup allows use of subtracted intensity measurements, instead of direct or homodyne measurements - a significant practical advantage. Bright, super-sensitive phase estimation of an object with different light fields for interaction and detection is possible.

Mar 10, 20200 citations

Versatile Super-Sensitive Metrology Using Induced Coherence

Nathaniel R. Miller, Sven Ramelow, William N. Plick

We theoretically analyze the phase sensitivity of the Induced-Coherence (Mandel-Type) Interferometer, including the case where the sensitivity is "boosted" into the bright input regime with coherent-light seeding. We find scaling which reaches below the shot noise limit, even when seeding the spatial mode which does not interact with the sample – or when seeding the undetected mode. It is a hybrid of a linear and a non-linear (Yurke-Type) interferometer, and aside from the supersensitivity, is distinguished from other systems by "preferring" an imbalance in the gains of the two non-linearities (with the second gain being optimal at low values), and non-monotonic behavior of the sensitivity as a function of the gain of the second non-linearity. Furthermore, the setup allows use of subtracted intensity measurements, instead of direct (additive) or homodyne measurements – a significant practical advantage. Bright, super-sensitive phase estimation of an object with different light fields for interaction and detection is possible, with various potential applications, especially in cases where the sample may be sensitive to light, or is most interesting in frequency domains outside what is easily detected, or when desiring bright-light phase estimation with sensitive/delicate detectors. We use an analysis in terms of general squeezing and discover that super-sensitivity occurs only in this case – that is, the effect is not present with the spontaneous-parametric-down-conversion approximation, which many previous analyses and experiments have focused on.We theoretically analyze the phase sensitivity of the Induced-Coherence (Mandel-Type) Interferometer, including the case where the sensitivity is "boosted" into the bright input regime with coherent-light seeding. We find scaling which reaches below the shot noise limit, even when seeding the spatial mode which does not interact with the sample – or when seeding the undetected mode. It is a hybrid of a linear and a non-linear (Yurke-Type) interferometer, and aside from the supersensitivity, is distinguished from other systems by "preferring" an imbalance in the gains of the two non-linearities (with the second gain being optimal at low values), and non-monotonic behavior of the sensitivity as a function of the gain of the second non-linearity. Furthermore, the setup allows use of subtracted intensity measurements, instead of direct (additive) or homodyne measurements – a significant practical advantage. Bright, super-sensitive phase estimation of an object with different light fields for interaction and detection is possible, with various potential applications, especially in cases where the sample may be sensitive to light, or is most interesting in frequency domains outside what is easily detected, or when desiring bright-light phase estimation with sensitive/delicate detectors. We use an analysis in terms of general squeezing and discover that super-sensitivity occurs only in this case – that is, the effect is not present with the spontaneous-parametric-down-conversion approximation, which many previous analyses and experiments have focused on.

arXiv:1907.09004QuantumMay 26, 202110 citations

Quantum-Enhanced Metrology and Sensing

David S. Simon

Undergraduate texts in physicsJan 1, 20250 citations

Quantum Metrology with Linear Optics

V. V. Zemlyanov, N. S. Kirsanov, Michael Romanovich Perelshtein +5 more

Nov 8, 20180 citations

Noise constraints on sensitivity scaling in super-Heisenberg quantum metrology

Noah Lordi, John Drew Wilson, Murray Holland +1 more

Quantum-enhanced metrology surpasses classical metrology by improving estimation precision scaling with a resource $N$ (e.g., particle number or energy) from $1/\sqrt{N}$ to $1/N$ . Through the use of nonlinear effects, Roy and Braunstein~\cite{Roy2008} derived a $1/2^N$ scaling. However, later works argued this exponential improvement is unphysical and that even modest gains, like $1/N^2$ , may vanish under noise. We show that, in the presence of small errors, the nonlinear interactions enabling metrological enhancement induce emergent errors. The errors propagate through the sensing protocol and are magnified proportional to any intended non-linear enhancement. We identify a critical value of the parameter to be estimated, for a fixed error, below which the emergent errors can be avoided.Quantum-enhanced metrology surpasses classical metrology by improving estimation precision scaling with a resource $N$ (e.g., particle number or energy) from $1/\sqrt{N}$ to $1/N$. Through the use of nonlinear effects, Roy and Braunstein~\cite{Roy2008} derived a $1/2^N$ scaling. However, later works argued this exponential improvement is unphysical and that even modest gains, like $1/N^2$, may vanish under noise. We show that, in the presence of small errors, the nonlinear interactions enabling metrological enhancement induce emergent errors. The errors propagate through the sensing protocol and are magnified proportional to any intended non-linear enhancement. We identify a critical value of the parameter to be estimated, for a fixed error, below which the emergent errors can be avoided.

arXiv:2504.03638Apr 4, 20250 citations

Quantum-enhanced metrology surpasses classical metrology by improving estimation precision scaling with a resource

N

(e.g., particle number or energy) from

1/\sqrt{N}

1/N

. Through the use of nonlinear effects, Roy and Braunstein~\cite{Roy2008} derived a

1/2^N

scaling. However, later works argued this exponential improvement is unphysical and that even modest gains, like

1/N^2

, may vanish under noise. We show that, in the presence of small errors, the nonlinear interactions enabling metrological enhancement induce emergent errors. The errors propagate through the sensing protocol and are magnified proportional to any intended non-linear enhancement. We identify a critical value of the parameter to be estimated, for a fixed error, below which the emergent errors can be avoided.