Quantum cryptography exploits principles of quantum physics for the secure processing of information. A prominent example is secure communication, i.e., the task of transmitting confidential messages from one location to another. The cryptographic requirement here is that the transmitted messages remain inaccessible to anyone other than the designated recipients, even if the communication channel is untrusted. In classical cryptography, this can usually only be guaranteed under computational hardness assumptions, e.g., that factoring large integers is infeasible. In contrast, the security of quantum cryptography relies entirely on the laws of quantum mechanics. Here we review this physical notion of security, focusing on quantum key distribution and secure communication.

翻译：量子加密学利用量子物理原理安全处理信息。一个突出的例子是安全通信,即从一个地点向另一个地点传送机密信息的任务。这里的加密要求是,除了指定接收人之外,任何人仍然无法接触所发送的信息,即使通信渠道不可信。在古典加密学中,这通常只能在计算硬性假设下得到保证,例如,将大整数考虑在内是不可行的。相反,量子加密学的安全完全依赖量子机械法。我们在这里审查这种实际的安全概念,重点是量子钥匙的分布和安全通信。