Abstract
Continuous variable (CV) quantum key distribution (QKD) provides a powerful setting for secure quantum communications, thanks to the use of room-temperature off-the-shelf optical devices and the potential to reach much higher rates than the standard discrete-variable counterpart. In this work, we provide a general framework for studying the composable finite-size security of CV-QKD with Gaussian-modulated coherent-state protocols under various levels of trust for the loss and noise experienced by the parties. Our study considers both wired (i.e., fiber-based) and wireless (i.e., free-space) quantum communications. In the latter case, we show that high key rates are achievable for short-range optical wireless (LiFi) in secure quantum networks with both fixed and mobile devices. Finally, we extend our investigation to microwave wireless (WiFi) discussing security and feasibility of CV-QKD for very short-range applications.
Highlights
Quantum key distribution (QKD) [1] enables the generation of secret keys between two or more authenticated parties by resorting to the fundamental laws of quantum mechanics
II, we provide a general framework for the composable security of continuous variable (CV)-QKD, which accounts for levels of trust in the loss and noise of the communication
As mentioned in the previous subsection, the performance in this general scenario can be lower-bounded by the extreme case where the receiver is assumed to be fixed at the maximum distance zmax from the transmitter
Summary
Quantum key distribution (QKD) [1] enables the generation of secret keys between two or more authenticated parties by resorting to the fundamental laws of quantum mechanics. While composable security is typically assessed against collective or coherent attacks, experiments may involve some additional (realistic) assumptions that elude this theory These assumptions may concern some level of trusted noise in the setups (e.g., this is often the case for the electronic noise of the detector) or some realistic constraint on the eavesdropper, Eve (e.g., it may be considered to be passive in line-of-sight free-space implementations). We study the more trustful scenario where both detector’s loss and noise are considered to be trusted, so that Eve is excluded from side-channels to the receiver We show how these assumptions can nontrivially increase the composable key rates of Gaussian-modulated CV-QKD protocols and tolerate higher dBs. In our analysis, we investigate the free-space setting, for near-range wireless quantum communications at optical frequencies (LiFi).
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