Heralded Distribution of Single-Photon Path Entanglement

Caspar, Patrik; Verbanis, Ephanielle; Oudot, Enky; Maring, Nicolas; Samara, Farid; Caloz, Misael; Perrenoud, Matthieu; Sekatski, Pavel; Martin, Anthony; Sangouard, Nicolas; Zbinden, Hugo; Thew, Rob

doi:10.1103/physrevlett.125.110506

Cited by 22 publications

(17 citation statements)

References 25 publications

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“…Moreover, the single photon delocalized into two modes (the p = 1 case in formula 1) has been used to build reliable quantum repeaters networks [21,22] that require less resources and are less sensitive to source of experimental inefficiencies than other platforms [23]. Therefore we believe that our work constitutes a basic ingredient to devise quantum information protocols based on Bell-nonclassicality with minimal physical resources, such as device-independent quantum key distribution or self-testing.…”

Section: Introductionmentioning

confidence: 99%

Optimal interferometry for Bell$-$nonclassicality by a vacuum$-$one$-$photon qubit

Das¹,

Karczewski²,

Mandarino³

et al. 2021

Preprint

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We show how to robustly violate local realism within the weak-field homodyne measurement scheme for any superposition of one photon with vacuum. Our setup involves tunable beamsplitters at the measurement stations, and the local oscillator fields significantly varying between the settings. As photon number resolving measurements are now feasible, we advocate for the use of the Clauser-Horne Bell inequalities for detection events using precisely defined numbers of photons. We find a condition for an optimal measurement settings for the maximal violation of the Clauser-Horne inequality with weak-field homodyne detection, which states that the reflectivity of the local beamsplitter must be equal to the strength of the local oscillator field. We show that this condition holds not only for the vacuum-one-photon qubit input state, but also for the Two-Mode Squeezed Vacuum state, which suggests its generality as a property of weak-field homodyne detection with photon-number resolution. Our findings suggest a possible path to employ such scenarios in device-independent quantum protocols.

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Section: Introductionmentioning

confidence: 99%

Optimal interferometry for Bell$-$nonclassicality by a vacuum$-$one$-$photon qubit

Das¹,

Karczewski²,

Mandarino³

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…A combination of this approach with homodyne measurements was investigated in [12], while an adaptation to multimode input states was given in [9]. Optical displacement was also used in a scheme for a heralded distribution of a singleparticle entanglement [20]. We shall not analyze the approach of [18] as, first, their proof of violation of local realism is impeccable, and second, despite the fact that their scheme involves only all-optical measurements, the employed technique is essentially different from the ones of TWC and Hardy.…”

Section: Introductionmentioning

confidence: 99%

Can single photon excitation of two spatially separated modes lead to a violation of Bell inequality via homodyne measurements?

Das,

Karczewski,

Mandarino

et al. 2021

Preprint

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The first one originates from a paper by Tan, Walls and Collett (TWC) [1], in which homodyne-based coincidence intensity measurements with weak coherent light as local auxiliary fields were used to violate the Bell-like inequality of [14].However, the Bell-like inequality in [14] does not rest entirely on Bell's assumptions. Because of that, one can question whether the TWC scheme can be used to violate local realism. For instance, Santos [15] provided an ad hoc local realistic model for the correlation functions considered by TWC. Recently, this line of critique has been reinforced in [16] by presenting a model that reproduces all detection events in the TWC experimental proposal for the range of local oscillator strengths for which the paper [1] reported 'nonlocality' of the single-photon state. In the section III B of this work we show that optical Bell inequalities [17], which must hold for any local realistic description, are not violated for the TWC setup. Thus this case is closed. Still, TWC correlations are interesting in themselves, and variants of this scheme have been realized experimentally in [4] and [11]. In section V we show how to use the CHSH-like inequality of [14] as an entanglement witness.Another idea was put forward by Hardy [2]. He considered states q |00 b1b2 + r √ 2 (|01 b1b2 + |10 b1b2 ), with q = 0

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“…A promising system to realize generalized N -qubit perfect W-states is a single photon shared between N spatial modes [23][24][25][26][27][28]. Single photon path entangled states has been reported to be useful for applications in quantum information processing [26,29,30].…”

Section: Introductionmentioning

confidence: 99%

“…These conditions involve violation of certain inequality relations by entangled states and can be verified experimentally. Entanglement witness operators are also used to detect the entanglement of two-mode and multi-mode single photon systems [27,28,52].…”

Section: Introductionmentioning

confidence: 99%

Generation and entanglement study of N-mode single photon perfect W-state

Swain¹,

Karthick²,

Rai³

et al. 2021

Preprint

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We propose schemes to generate N -mode single photon perfect W-state and derive entanglement conditions to detect the entanglement of all generalized N -mode single photon perfect W-states. These states are suitable for perfect teleportation and superdense coding over other maximally entangled states belonging to W-class. Based on the evolution of single photon wave function in scalable integrated photonic lattices, we present schemes for the preparation of N -mode single photon perfect W-state at desired propagation distance. The integrated waveguide structures can precisely be fabricated and offer low photon propagation losses. We consider both planar and ring type waveguide structures for generation of the N -mode single photon perfect W-state. We derive set of generalized entanglement detection conditions using sum uncertainty relations of generalized su(2) algebra operators. We show that any given genuinely entangled N -mode single photon state is a squeezed state of a specific su(2) algebra operator and can be expressed as superposition of a pair of generalized N -mode single photon perfect W-states which are eigenstates of that specific su(2) algebra operator. We further prove that the squeezed states of an su(2) algebra operator satisfy the entanglement condition obtained using that operator and hence the usefulness of the proposed set of entanglement conditions to detect the entanglement of genuinely entangled single photon states. Finally, we propose an experimental scheme to verify the entanglement of generalized N -mode single photon perfect W-states using an integrated photonic circuit that consists of directional couplers and phase shifters and show that the same photonic circuit can also be used to generate generalized N -mode single photon perfect W-states. Our results show that optical waveguide structures are ideal platforms for generation and verification of multipartite entangled states which could find novel applications in quantum information science.

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Heralded Distribution of Single-Photon Path Entanglement

Cited by 22 publications

References 25 publications

Optimal interferometry for Bell$-$nonclassicality by a vacuum$-$one$-$photon qubit

Optimal interferometry for Bell$-$nonclassicality by a vacuum$-$one$-$photon qubit

Can single photon excitation of two spatially separated modes lead to a violation of Bell inequality via homodyne measurements?

Generation and entanglement study of N-mode single photon perfect W-state

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