Floodlight quantum key distribution: Demonstrating a framework for high-rate secure communication

Zheshen Zhang, Quntao Zhuang, Franco N.C. Wong, Jeffrey H. Shapiro

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Floodlight quantum key distribution (FL-QKD) is a radically different QKD paradigm that can achieve gigabit-per-second secret-key rates over metropolitan area distances without multiplexing [Q. Zhuang, Phys. Rev. A 94, 012322 (2016)2469-992610.1103/PhysRevA.94.012322]. It is a two-way protocol that transmits many photons per bit duration and employs a high-gain optical amplifier, neither of which can be utilized by existing QKD protocols, to mitigate channel loss. FL-QKD uses an optical bandwidth that is substantially larger than the modulation rate and performs decoding with a unique broadband homodyne receiver. Essential to FL-QKD is Alice's injection of photons from a photon-pair source - in addition to the light used for key generation - into the light she sends to Bob. This injection enables Alice and Bob to quantify Eve's intrusion and thus secure FL-QKD against collective attacks. Our proof-of-concept experiment included 10 dB propagation loss - equivalent to 50 km of low-loss fiber - and achieved a 55 Mbit/s secret-key rate (SKR) for a 100 Mbit/s modulation rate, as compared to the state-of-the-art system's 1 Mbit/s SKR for a 1 Gbit/s modulation rate [M. Lucamarini, Opt. Express 21, 24550 (2013)OPEXFF1094-408710.1364/OE.21.024550], representing ∼500-fold and ∼50-fold improvements in secret-key efficiency (bits per channel use) and SKR (bits per second), respectively.

Original languageEnglish (US)
Article number012332
JournalPhysical Review A
Issue number1
StatePublished - Jan 26 2017
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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