English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Loophole-free Bell tests are essential if one wishes to performdevice-independent quantum key distribution (QKD), since any loophole could beused by a potential adversary to undermine the security of the protocol.Crucial work by Eberhard demonstrated that weakly entangled two-qubit stateshave a far greater resistance to the detection loophole than maximallyentangled states, allowing one to close the loophole with detection efficiencygreater than 2/3. Here we demonstrate that this same limit holds forphoton-counting CHSH Bell tests which can demonstrate non-locality for higherdimensional multiphoton states such as two-mode squeezed vacuum and generalizedHolland-Burnett states. In fact, we show evidence that these tests are in somesense universal, allowing feasible detection loophole-free tests for anymultiphoton bipartite state, as long as the two modes are well correlated inphoton number. Additionally, by going beyond the typical two-input two-outputBell scenario, we show that there are also photon-counting CGLMP inequalitieswhich can also match the Eberhard limit, paving the way for more exoticloophole-free Bell tests. Finally we show that by exploiting this increasedloss tolerance of non maximally entangled states, one can increase the keyrates and loss tolerances of QKD protocols based on photon-counting tests.

Eberhard limit for photon-counting Bell tests and its utility in quantum key distribution