A well-known empirical rule for the demand of wireless communication systems is that of Edholm’s law of bandwidth. It states that the demand for bandwidth in wireless short-range communications doubles every 18 months. With the growing demand for bandwidth and the decreasing cell size of wireless systems, terahertz (THz) communication systems are expected to become increasingly important in modern day applications. With this expectation comes the need for protecting users’ privacy and security in the best way possible. With that in mind, we show that quantum key distribution can operate in the THz regime and we derive the relevant secret key rates against realistic collective attacks. In the extended THz range (from 0.1 to 50 THz), we find that below 1 THz, the main detrimental factor is thermal noise, while at higher frequencies it is atmospheric absorption. Our results show that high-rate THz quantum cryptography is possible over distances varying from a few meters using direct reconciliation, to about 220m via reverse reconciliation. We also give a specific example of the physical hardware and architecture that could be used to realize our THz quantum key distribution scheme.

中文翻译：

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太赫兹量子密码学

无线通信系统需求的一个众所周知的经验规则是 Edholm 带宽定律。它指出，无线短程通信对带宽的需求每 18 个月就会翻一番。随着对带宽需求的不断增长和无线系统小区规模的缩小，太赫兹 (THz) 通信系统有望在现代应用中变得越来越重要。伴随着这种期望，需要以尽可能最好的方式保护用户的隐私和安全。考虑到这一点，我们证明了量子密钥分发可以在太赫兹机制下运行，并且我们推导出相关的秘密密钥率来对抗现实的集体攻击。在扩展的太赫兹范围内（从 0.1 到 50 THz），我们发现低于 1 THz，主要的不利因素是热噪声，而在更高的频率，它是大气吸收。我们的结果表明，高速太赫兹量子密码学可以在从使用直接协调的几米到通过反向协调的大约 220 米的距离上进行。我们还给出了可用于实现我们的太赫兹量子密钥分发方案的物理硬件和架构的具体示例。