Device-independent quantum key distribution with generalized two-mode Schrödinger cat states

Curtis J. Broadbent, Kevin Marshall, Christian Weedbrook, John C. Howell

Research output: Contribution to journalArticlepeer-review


We show how weak nonlinearities can be used in a device-independent quantum key distribution (QKD) protocol using generalized two-mode Schrödinger cat states. The QKD protocol is therefore shown to be secure against collective attacks and for some coherent attacks. We derive analytical formulas for the optimal values of the Bell parameter, the quantum bit error rate, and the device-independent secret key rate in the noiseless lossy bosonic channel. Additionally, we give the filters and measurements which achieve these optimal values. We find that, over any distance in this channel, the quantum bit error rate is identically zero, in principle, and the states in the protocol are always able to violate a Bell inequality. The protocol is found to be superior in some regimes to a device-independent QKD protocol based on polarization entangled states in a depolarizing channel. Finally, we propose an implementation for the optimal filters and measurements.

Original languageEnglish
Article number052318
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number5
StatePublished - 16 Nov 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics


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