Semi device independence of the BB84 protocol

Woodhead, Erik

doi:10.1088/1367-2630/18/5/055010

Cited by 12 publications

(12 citation statements)

References 30 publications

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“…In terms of entanglement being a resource for quantum key distribution (QKD), we derive security bounds for implementations of the BB84 and the six-state protocols that use entangled qubits. Similar work was done for the BB84 protocol in [7], as well as in the recent, independent work [8]. This work fits in the broad class of 'measurement-device-independent' (MDI) approaches, in which all the imperfections of the measurement devices and detectors do not need to be modelled.…”

Section: Introductionmentioning

confidence: 62%

“…We find ¢ = r r BB84 BB84 : the relaxation of assumption on measurement does not affect the secret key fraction in the BB84 protocol. This result had been obtained analytically thanks to the special properties of p BB84 [7] and has been recently re-derived in a parallel work [8]. These analytical derivations are possible thanks to the high symmetry of the BB84 protocol and can in fact be made with by assuming only that Alice measures a qubit, while Bobʼs system has arbitrary dimension.…”

Section: Application To the Bb84 And Six-states Protocolsmentioning

confidence: 84%

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Measurement-device-independent quantification of entanglement for given Hilbert space dimension

2016

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We address the question of how much entanglement can be certified from the observed correlations and the knowledge of the Hilbert space dimension of the measured systems. We focus on the case in which both systems are known to be qubits. For several correlations (though not for all), one can certify the same amount of entanglement as with state tomography, but with fewer assumptions, since nothing is assumed about the measurements. We also present security proofs of quantum key distribution (QKD) without any assumption on the measurements. We discuss how both the amount of entanglement and the security of QKD are affected by the inefficiency of detectors in this scenario.

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Section: Introductionmentioning

confidence: 62%

Section: Application To the Bb84 And Six-states Protocolsmentioning

confidence: 84%

Measurement-device-independent quantification of entanglement for given Hilbert space dimension

2016

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“…Concentrating on qubit systems, then, we know from security analyses of the BB84 protocol (see e.g. [24] or [25,26]) that the conditional entropy of the outcome of a Pauli Z measurement by Alice is lower bounded by…”

Section: Short Derivation For Chshmentioning

confidence: 99%

Device-independent quantum key distribution with asymmetric CHSH inequalities

Woodhead

Acín

Pironio

2021

Quantum

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102

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The simplest device-independent quantum key distribution protocol is based on the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality and allows two users, Alice and Bob, to generate a secret key if they observe sufficiently strong correlations. There is, however, a mismatch between the protocol, in which only one of Alice's measurements is used to generate the key, and the CHSH expression, which is symmetric with respect to Alice's two measurements. We therefore investigate the impact of using an extended family of Bell expressions where we give different weights to Alice's measurements. Using this family of asymmetric Bell expressions improves the robustness of the key distribution protocol for certain experimentally-relevant correlations. As an example, the tolerable error rate improves from 7.15% to about 7.42% for the depolarising channel. Adding random noise to Alice's key before the postprocessing pushes the threshold further to more than 8.34%. The main technical result of our work is a tight bound on the von Neumann entropy of one of Alice's measurement outcomes conditioned on a quantum eavesdropper for the family of asymmetric CHSH expressions we consider and allowing for an arbitrary amount of noise preprocessing.

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“…[12] considers another SDI model, one in which only the dimension of the system is known but not the measurements, and provides tools to quantify entanglement and security proofs for QKD. [40] studies the security of BB84 under the even weaker assumption that the dimension of only one of the systems is constrained to be a qubit. [20] shows that considering higher-dimensional systems (still in the SDI model, where a bound on the dimension of the devices is given a priori) can lead to improve rates, albeit at a higher computational cost.…”

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confidence: 99%

Focus on device independent quantum information

2016

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The field of quantum information is born out of a sequence of surprising discoveries in the 1980s, all building on the same deep insight: the counter-intuitive quantum properties of particles such as photons or electrons can be put to task in order to accomplish certain computational, cryptographic, and information-theoretic tasks impossible to realize by purely classical means. A famous example is the cryptographic problem of key distribution, for which Bennett and Brassard devised the first quantum protocol in 1984 [6] and whose security relies on the no-cloning principle of quantum mechanics. Another example is the computational problem of factoring large numbers, for which Shor devised the first efficient quantum algorithm in 1994 [32] by exploiting the possibility for quantum systems to evolve in superpositions of exponentially many different states.In this early history, and until very recently, the violation of Bell inequalities was simply seen as yet another feature distinguishing the quantum processing of information from a classical one. It provided one of the initial motivations for developing a better understanding of entangled states; it was recognized as a key factor responsible for the quantum advantage in communication complexity protocols; it was frequently used in experiments to demonstrate oneʼs ability to generate and manipulate entanglement. It also played an important conceptual role, as it established that the predictions of quantum theory, including its claimed information processing advantages, could not be naively reproduced by a classical theory. But overall the manifestation of quantum non-locality was just another way to evidence the weirdness of quantum theory, on par with the nocloning principle or the uncertainty of quantum measurements in having little consequence for practical applications.In very recent years, however, the violation of Bell inequalities has acquired a special status that is starting to revolutionize our understanding of the information-theoretic possibilities of quantum information. Indeed, not only are the properties of quantum states and measurements leading to the violation of Bell inequalities unique in the sense of having no classical explanation, but they also often uniquely single out the quantum system itself. More precisely, given a black-box device that is verifiably violating a Bell inequality, quantum theory allows for a virtually unique way in which this can be accomplished. Furthermore, for the many tasks for which quantum information provides an advantage, there often turns out to be a protocol whose advantage essentially amounts to the sufficiently large violation of a certain Bell inequality.Taken together, these two phenomena lead to the following observation: it is possible to devise quantum information protocols whose correctness can be certified even when they are run with untrusted quantum devices, on which no a priori assumptions are made. Hence the name 'device-independence' (DI) to refer to such protocols. The implications of this are pr...

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Semi device independence of the BB84 protocol

Cited by 12 publications

References 30 publications

Measurement-device-independent quantification of entanglement for given Hilbert space dimension

Measurement-device-independent quantification of entanglement for given Hilbert space dimension

Device-independent quantum key distribution with asymmetric CHSH inequalities

Focus on device independent quantum information

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