Generation of time-domain-multiplexed two-dimensional cluster state

Asavanant, Warit; Shiozawa, Yu; Yokoyama, Shohei; Charoensombutamon, Baramee; Emura, Hiroki; Alexander, Rafael N.; Takeda, Shuntaro; Yoshikawa, Jun–ichi; Menicucci, Nicolas C.; Yonezawa, Hidehiro; Furusawa, Akira

doi:10.1126/science.aay2645

Cited by 399 publications

(345 citation statements)

References 37 publications

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“…Applying TDM for QIP enables us, in principle, to generate unlimited scales of quantum entanglement in finite space. 1,4 Recently, large-scale quantum entanglement of over one-million states 5 and two-dimensional (2D) cluster states 6 have been successfully demonstrated by using TDM.…”

Section: Introductionmentioning

confidence: 99%

Continuous-wave 6-dB-squeezed light with 2.5-THz-bandwidth from single-mode PPLN waveguide

et al. 2020

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Terahertz (THz)-bandwidth continuous-wave (CW) squeezed light is essential for integrating quantum processors with time-domain multiplexing (TDM) by using optical delay line interferometers. Here, we utilize a single-pass optical parametric amplifier (OPA) based on a single-spatial-mode periodically poled ZnO:LiNbO3 waveguide, which is directly bonded onto a LiTaO3 substrate. The single-pass OPA allows THz bandwidth, and the absence of higher-order spatial modes in the single-spatial-mode structure helps to avoid degradation of squeezing. In addition, the directly bonded ZnO-doped waveguide has durability for highpower pump and shows small photorefractive damage. Using this waveguide, we observe CW 6.3-dB squeezing at 20-MHz sideband by balanced homodyne detection. This is the first realization of CW squeezing with a single-pass OPA at a level exceeding 4.5 dB, which is required for the generation of a two-dimensional cluster state. Furthermore, the squeezed light shows 2.5-THz spectral bandwidth. The squeezed light will lead to the development of a high-speed on-chip quantum processor using TDM with a centimeter-order optical delay line.

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Section: Introductionmentioning

confidence: 99%

Continuous-wave 6-dB-squeezed light with 2.5-THz-bandwidth from single-mode PPLN waveguide

et al. 2020

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“…The key idea of such a quantum network, be it for communication or for distributed computation, is to connect a large number of nodes via quantum entanglement [3,4]. A platform that is particularly promising for such applications is continuous-variable quantum optics, where large entangled graph states can be deterministically produced [5][6][7][8][9]. Even though this allows us to produce intricate quantum networks, the resulting Gaussian quantum states still have a positive Wigner function.Negativity of the Wigner function has been identified as a necessary ingredient for implementing processes that cannot be simulated efficiently with classical resources [10,11], and is therefore an essential resource [12,13] to achieve a quantum advantage.…”

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confidence: 99%

Remote Generation of Wigner Negativity through Einstein-Podolsky-Rosen Steering

Walschaers

Treps

2020

Phys. Rev. Lett.

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Negativity of the Wigner function is seen as a crucial resource for reaching a quantum computational advantage with continuous variable systems. However, these systems, while they allow for the deterministic generation of large entangle states, require an extra element such as photon subtraction to obtain such negativity. Photon subtraction is known to affect modes beyond the one where the photon is subtracted, an effect which is governed by the correlations of the state. In this manuscript, we build upon this effect to remotely prepare states with Wigner-negativity. More specifically, we show that photon subtraction can induce Wigner-negativity in a correlated mode if and only if that correlated mode can perform Einstein-Podolsky-Rosen steering in the mode of subtraction.Manipulating networks is at the heart of information processing and communication. Hence, the growing interest in a quantum internet [1, 2] is a logical step in the developments of quantum technologies. The key idea of such a quantum network, be it for communication or for distributed computation, is to connect a large number of nodes via quantum entanglement [3,4]. A platform that is particularly promising for such applications is continuous-variable quantum optics, where large entangled graph states can be deterministically produced [5][6][7][8][9]. Even though this allows us to produce intricate quantum networks, the resulting Gaussian quantum states still have a positive Wigner function.Negativity of the Wigner function has been identified as a necessary ingredient for implementing processes that cannot be simulated efficiently with classical resources [10,11], and is therefore an essential resource [12,13] to achieve a quantum advantage. In networked quantum technologies it is, thus, crucial to generate and distribute Wigner-negativity in the nodes of a quantum network. In this spirit we focus here on the remote generation of Wigner-negativity, such that operations in one node of a quantum network create negativity in the Wigner function of another node while upholding the entanglement in the quantum network.Photon subtraction [14-16] is a natural candidate for such operation. In previous work, we showed that the subtraction of a photon causes an interplay between correlations and non-Gaussian features [17]. In the specific case of graph states, it was shown that non-Gaussian properties, induced by photon subtraction, propagate through the system [18,19], however it is far from clear whether this mediated non-Gaussianity has quantum features (see also [20]). Hence, here we turn the question around, and ask what type of correlations are required to remotely generate negativity of the Wigner function through photon subtraction. We show that Einstein-Podolsky-Rosen (EPR) steering [21-25] is a necessary and sufficient condition.In its essence, EPR steering focusses on the the structure of conditional quantum probabilities: when Alice and Bob share a quantum state, Bob can perform measurements on his part of the state and Alice can condition her...

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“…Twenty years ago, generating a two-mode squeezed-vacuum state and measuring EPR variables were the key ingredients in the first demonstration of unconditional quantum teleportation [62]. Today, ideas for modal (continuousvariable) cluster-state computation [63,64] live on two-mode squeezing; using this resource, experimentalists have demonstrated entanglement of large numbers of modes in one-and now two-dimensional cluster states [65]. The list goes on, but this paper does not.…”

Section: Discussionmentioning

confidence: 96%

Reframing SU(1,1) Interferometry

Caves

2020

Adv Quantum Tech

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interferometry, proposed in a classic 1986 paper by Yurke, McCall, and Klauder [Phys. Rev. A 33, 4033 (1986)], involves squeezing, displacing, and then unsqueezing two bosonic modes. It has, over the past decade, been implemented in a variety of experiments. Here I take SU(1,1) interferometry apart, to see how and why it ticks. SU(1,1) interferometry arises naturally as the two-mode version of active-squeezing-enhanced, back-action-evading measurements aimed at detecting the phase-space displacement of a harmonic oscillator subjected to a classical force. Truncating an SU(1,1) interferometer, by omitting the second two-mode squeezer, leaves a prototype that uses the entanglement of two-mode squeezing to detect and characterize a disturbance on one of the two modes from measurement statistics gathered from both modes. 1 2 (v G /c) 2 2 × 10 −7 , corresponding to a coherence time τ = 1/∆ν 5 × 10 6 τ a , where τ a = 1/ν a is the axion period and thus the period of the cavity mode. One * Electronic address: ccaves@unm.edu arXiv:1912.12530v1 [quant-ph] 28 Dec 2019 II. SU(1,1) INTERFEROMETRY , McCall, and Klauder [32] introduced the notion of SU(1,1) interferometry by replacing the beamsplitters of a standard SU(2) interferometer with active elements now called two-mode squeezers. YurkeA standard interferometer uses beamsplitters acting on a pair of modes, a and b, to send waves down two different paths and to bring those waves into interference after they have received phase shifts that one wants to detect. A standard interferometer is

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Generation of time-domain-multiplexed two-dimensional cluster state

Cited by 399 publications

References 37 publications

Continuous-wave 6-dB-squeezed light with 2.5-THz-bandwidth from single-mode PPLN waveguide

Continuous-wave 6-dB-squeezed light with 2.5-THz-bandwidth from single-mode PPLN waveguide

Remote Generation of Wigner Negativity through Einstein-Podolsky-Rosen Steering

Reframing SU(1,1) Interferometry

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