Quantum-enhanced interferometry with asymmetric beam splitters

Zhong, Wei; Wang, Fan; Zhou, Lan; Xu, Peng; Sheng, Yu‐Bo

doi:10.1007/s11433-019-1503-0

Cited by 31 publications

(23 citation statements)

References 88 publications

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“…R||αβ| sin ∆θ (38) While for the two-parameter QFI, regardless of the value of the input PMC (∆θ) we can find an optimum transmission coefficient (35) bringing us to the maximal QFI (36), this is no longer true for F (i) . If sin ∆θ = 0, then…”

Section: B Double Coherent Inputmentioning

confidence: 94%

Single- versus two-parameter Fisher information in quantum interferometry

Ataman

2020

Phys. Rev. A

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In this paper we reconsider the single parameter quantum Fisher information (QFI) and compare it with the two-parameter one. We find simple relations connecting the single parameter QFI (both in the asymmetric and symmetric phase shift cases) to the two parameter Fisher matrix coefficients. Following some clarifications about the role of an external phase [Phys. Rev. A 85, 011801(R) (2012)], the single-parameter QFI and its over-optimistic predictions have been disregarded in the literature. We show in this paper that both the single-and two-parameter QFI have physical meaning and their predicted quantum Cramér-Rao bounds are often attainable with the appropriate experimental setup. Moreover, we give practical situations of interest in quantum metrology, where the phase sensitivities of a number of input states approach the quantum Cramér-Rao bound induced by the single-parameter QFI, outperforming the two-parameter QFI.

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Section: B Double Coherent Inputmentioning

confidence: 94%

Single- versus two-parameter Fisher information in quantum interferometry

Ataman

2020

Phys. Rev. A

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“…As we will emphasize in this paper, optimizing the transmission coefficient of the first BS is enough to ensure the maximization of the QFI. This is due to the fact that the second BS has no effect whatsoever on the QFI calculation [26]. The statement remains true for both single-and two-parameter QFI scenarios, in other words, with or without an external phase reference.…”

Section: Introductionmentioning

confidence: 84%

“…A plethora of quantum states have been shown to have a quantum metrological interest [1,14,[30][31][32][33][45][46][47][48][49][50][51]. The discussions however, were carried out in the balanced case only, with few exceptions [24][25][26]. In this section we re-discuss a number of these states in the non-balanced scenario for all three QFIs.…”

Section: Gaussian and Non-gaussian Input State Examplesmentioning

confidence: 99%

“…While optimum transmission coefficients for an unbalanced interferometer have been reported for some given constraints [26,27] or for specific input states [24], no universal solution to this problem was proposed, to the best of our knowledge. Moreover, in the previous studies [26,27], a specific QFI was considered only, namely the two-parameter QFI F (2p) .…”

Section: Introductionmentioning

confidence: 98%

“…As already discussed in the literature, the balanced case is not always optimal [24,25] and unbalancing the interferometer can actually be beneficial [24][25][26]. When the interferometer is unbalanced, two supplementary parameters appear, namely the transmission coefficients of the first (T ) and second (T ′ ) beam splitters (BS).…”

Section: Introductionmentioning

confidence: 99%

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Quantum Fisher information maximization in an unbalanced interferometer

Ataman

2022

Preprint

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In this paper we provide the answer to the following question: given an arbitrary pure input state and a general, unbalanced, Mach-Zehnder interferometer, what transmission coefficient of the first beam splitter maximizes the quantum Fisher information (QFI)? We consider this question for both single-and two-parameter QFI, or, in other words, with or without having access to an external phase reference. We give analytical results for all involved scenarios. It turns out that, for a large class of input states, the balanced (50/50) scenario yields the optimal two-parameter QFI, however this is far from being a universal truth. When it comes to the single-parameter QFI, the balanced scenario is rarely the optimal one and an unbalanced interferometer can bring a significant advantage over the balanced case. We also state the condition imposed upon the input state so that no metrological advantage can be exploited via an external phase reference. Finally, we illustrate and discuss our assertions through a number of examples, including both Gaussian and non-Gaussian input states.

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Deterministic Conversion of Hyperentangled States with Error‐Heralded Quantum Units

Du,

Ma,

Ren

et al. 2024

Annalen der Physik

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In the paper, the possibility of two complete conversions is investigated, one is from the two‐photon hyperentangled Knill–Laflamme–Milburn (KLM) state to hyperentangled Bell states, the other is from three‐photon KLM state to the hyperentangled Greenberger–Horne–Zeilinger states, for photonic systems hyper‐encoded in polarization and spatial degrees of freedom assisted by error‐heralded quantum units (EHQUs). The system inhomogeneity and/or the imperfect photon scattering often restrict the performance of effective conversions of two types of hyperentangled states, and result in the reductions of the fidelity and the efficiency in tangible quantum information technologies. The polarization EHQU and spatial EHQU are two critical tools for actualizing two hyperentangled conversions in a heralded way, as the errors stemming from the system inhomogeneity and practically imperfect scattering are converted into efficacious responses of the detectors in our protocols. Thus, the fidelities of these conversion cases keep unchanged and have close to unity fidelities, which deepen the understanding of the properties of hyperentanglement.

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Quantum-enhanced interferometry with asymmetric beam splitters

Cited by 31 publications

References 88 publications

Single- versus two-parameter Fisher information in quantum interferometry

Single- versus two-parameter Fisher information in quantum interferometry

Quantum Fisher information maximization in an unbalanced interferometer

Deterministic Conversion of Hyperentangled States with Error‐Heralded Quantum Units

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