Violating Bell inequalities with entangled optical frequency combs and multipixel homodyne detection

Plick, William N.; Arzani, Francesco; Treps, Nicolas; Diamanti, Eleni; Markham, Damian

doi:10.1103/physreva.98.062101

Cited by 14 publications

(7 citation statements)

References 30 publications

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“…With the canonical commutation relations we can show that [ q( f 1 ), q( f 2 ) n ] ∼ q( f 2 ) n−1 , which can be inserted in (174) to obtain…”

Section: A Deterministic Methodsmentioning

confidence: 99%

“…There has been a significant body of work about the violation of Bell inequalities in CV setups [171][172][173]. It is evident that this is an arduous task once one approaches a realistic experimental setting [174]. Here, we focus on one particular suggestion to test Bell non-locality based on a state's Wigner function [175,176].…”

Section: Non-gaussianity and Bell Inequalitiesmentioning

confidence: 99%

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Non-Gaussian Quantum States and Where to Find Them

Walschaers

2021

Preprint

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Gaussian states have played on important role in the physics of continuous-variable quantum systems. They are appealing for the experimental ease with which they can be produced, and for their compact and elegant mathematical description. Nevertheless, many proposed quantum technologies require us to go beyond the realm of Gaussian states and introduce non-Gaussian elements. In this Tutorial, we provide a roadmap for the physics of non-Gaussian quantum states. We introduce the phase-space representations as a framework to describe the different properties of quantum states in continuous-variable systems. We then use this framework in various ways to introduce extra structure in the state space. We explain how non-Gaussian states can be characterised not only through the negative values of their Wigner function, but also via other properties such as quantum non-Gaussianity and the related stellar rank. For multimode systems, we are naturally confronted with the question of how non-Gaussian properties behave with respect to quantum correlations. To answer this question, we first show how non-Gaussian states can be created by performing measurements on a subset of modes in a Gaussian state. Then, we highlight that these measured modes must be correlated via specific quantum correlations to the remainder of the system to create quantum non-Gaussian or Wigner-negative states. On the other hand, non-Gaussian operations are also shown to enhance or even create quantum correlations. Finally, we will demonstrate that Wigner negativity is a requirement to violate Bell inequalities and to achieve a quantum computational advantage. At the end of the Tutorial, we also provide an overview of several experimental realisations of non-Gaussian quantum states in quantum optics and beyond.

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“…With the canonical commutation relations we can show that [ q( f 1 ), q( f 2 ) n ] ∼ q( f 2 ) n−1 , which can be inserted in (174) to obtain…”

Section: A Deterministic Methodsmentioning

confidence: 99%

Section: Non-gaussianity and Bell Inequalitiesmentioning

confidence: 99%

Non-Gaussian Quantum States and Where to Find Them

Walschaers

2021

Preprint

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“…The quadrature operators of a multimode state can be measured by two different detection strategies. The first strategy undertakes a multimode homodyne measurement, [25][26][27] which applies a simultaneous measurement on all the supermodes. The second strategy, which allows for successive measurements on each supermode, first splits a supermode into different frequency bands using a quantum pulse gate (QPG), 28,29 then undertakes a homodyne measurement to each of the split supermodes.…”

Section: 1mentioning

confidence: 99%

Multimode CV‐QKD with non‐Gaussian operations

He¹,

Malaney²,

Green

2020

Quantum Engineering

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Summary Non‐Gaussian operations have been studied intensively in recent years due to their ability to increase the secret key rate for certain CV‐QKD protocols. However, most previous studies on such protocols are carried out in a single‐mode setting, even though in reality any quantum state contains multimode components in frequency space. In this work, we investigate the use of non‐Gaussian operations in a multimode CV‐QKD system. Our main finding is that, contrary to single‐mode CV‐QKD systems, in generic multimode CV‐QKD systems, it is possible to use non‐Gaussian operations to increase the optimized secret key rate. More specifically, we find that at losses of order 30dB, which represents a distance of order 160km and the effective maximum distance for CV‐QKD, the key rate for multimode non‐Gaussian operations can be orders of magnitude higher than single‐mode operations. Our results are important for real‐world CV‐QKD systems, especially those dependent on quantum error correction—a process that requires non‐Gaussian effects.

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“…We reveal the induced non-Gaussian features and observe how they spread among the entangled modes, depending on the mode in which the photon is subtracted. The resulting non-Gaussian multimode quantum states will have broad applications for universal quantum computing [8,9], entanglement distillation [10], and a nonlocality test [11].…”

mentioning

confidence: 99%

“…The selectivity and the controllability of the mode(s) for the photon subtraction make it possible to extend the non-Gaussianity of a quantum state to the multimode regime, which has been a main obstacle for scalable quantum information processing [1,2]. The availability of non-Gaussian multimode states will stimulate fundamental studies on multipartite entanglement [15] and multimode quantumness [29] by going beyond the Gaussian realm, as well as applications in quantum computing [8,9] and quantum communication [10,11]. In particular, the observed nontrivial interplay between photon subtraction and cluster states, confirming recent theoretical predictions [24], provides new insights into the fields of quantum networks [30] and quantum transport [31].…”

mentioning

confidence: 99%

Non-Gaussian quantum states of a multimode light field

et al. 2019

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Even though Gaussian quantum states of multimode light are promising quantum resources due to their scalability, non-Gaussianity is indispensable for quantum technologies, in particular to reach quantum computational advantage. However, embodying non-Gaussianity in a multimode Gaussian state remains a challenge as controllable non-Gaussian operations are hard to implement in a multimode scenario. Here, we report the first generation of non-Gaussian quantum states of a multimode light field by subtracting a photon in a desired mode from multimode Gaussian states, and observe negativity of the Wigner function. For entangled Gaussian states, we observe that photon subtraction makes non-Gaussianity spread among various entangled modes. In addition to applications in quantum technologies, our results shed new light on non-Gaussian multimode entanglement with particular emphasis on quantum networks.

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Violating Bell inequalities with entangled optical frequency combs and multipixel homodyne detection

Cited by 14 publications

References 30 publications

Non-Gaussian Quantum States and Where to Find Them

Non-Gaussian Quantum States and Where to Find Them

Multimode CV‐QKD with non‐Gaussian operations

Non-Gaussian quantum states of a multimode light field

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