Quantum-secure covert communication on bosonic channels
#MMPMID26478089
Bash BA
; Gheorghe AH
; Patel M
; Habif JL
; Goeckel D
; Towsley D
; Guha S
Nat Commun
2015[Oct]; 6
(?): 8626
PMID26478089
show ga
Computational encryption, information-theoretic secrecy and quantum cryptography
offer progressively stronger security against unauthorized decoding of messages
contained in communication transmissions. However, these approaches do not ensure
stealth--that the mere presence of message-bearing transmissions be undetectable.
We characterize the ultimate limit of how much data can be reliably and covertly
communicated over the lossy thermal-noise bosonic channel (which models various
practical communication channels). We show that whenever there is some channel
noise that cannot in principle be controlled by an otherwise arbitrarily powerful
adversary--for example, thermal noise from blackbody radiation--the number of
reliably transmissible covert bits is at most proportional to the square root of
the number of orthogonal modes (the time-bandwidth product) available in the
transmission interval. We demonstrate this in a proof-of-principle experiment.
Our result paves the way to realizing communications that are kept covert from an
all-powerful quantum adversary.
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