Mode-locked laser for spectrally multiplexed and network-compatible quantum memories

加拿大的经济、政治和社会福祉在很大程度上取决于安全的电子通信，例如电子银行、电子医疗、电子商务和电子政务。然而，目前的公钥密码系统依赖于未经证实的关于计算复杂性的假设，容易受到算法进步和更好的经典计算机技术的影响，并且随着量子计算机的出现而过时。因此，过去或现在编码和发送的信息的保密性，即使今天仍然得到保证，也容易受到未来密码破译技术的改进的影响，这可能导致在没有足够保护的情况下解码记录的信息，然后才失去重要性。量子密钥分配（QKD）采用特定量子态中制备的单个光子作为信息载体，有望最终解决这些问题：新技术无法损害安全性。然而，由于光子在传输过程中丢失，并且由于量子力学的基本限制（称为不可克隆定理）而无法使用放大器，因此QKD目前面临约200公里的距离限制。有趣的是，这种限制可以通过尚未存在的量子中继器来消除，这将在未来将量子计算机或原子钟连接到量子网络中发挥重要作用。这笔赠款将允许购买锁模皮秒激光器，这是需要初始化低温冷却的稀土离子掺杂晶体，用于存储量子状态编码成大量的光子在许多光谱通道。这些所谓的量子存储器是量子中继器和网络的关键组成部分，需要迫切改进。激光器将消除目前影响进一步发展的一个重要瓶颈，即将光谱复用从经典（电信）世界转换为量子通信的问题。如果及时获得，它将为我们在整个北美大陆进行可证明的安全通信的长期目标奠定基础。除了在各个职业层次培养高素质的人才，推进量子光学和量子通信领域的发展外，通过收购这种激光器，我们的研究将确保加拿大在过去十年对量子通信进行大量投资后，在这一重要领域保持竞争力。

The economic, political, and social well-being of Canada depends crucially on secure electronic communications, e.g. for e-banking, e-health, e-commerce, and e-government. Yet, current public key cryptosystem rely on unproven assumptions about computational complexity, are susceptible to algorithmic advances and better classical computer technology, and will become obsolete with the advent of the quantum computer. Hence, the secrecy of messages encoded and sent in the past or present, even if still ensured today, is vulnerable to future improvements in code breaking, which may lead to decoding of recorded messages with insufficient protection before they lose importance. Quantum key distribution (QKD), which employs individual photons prepared in specific quantum states as carriers of information, promises the ultimate solution to these problems: security that cannot be compromised by new technology. Yet, as photons get lost during transmission and amplifiers cannot be used due to a fundamental restriction of quantum mechanics known as the no-cloning theorem, QKD currently faces a distance limit of around 200 km. Interestingly, this limit can be removed through not-yet-existing quantum repeaters, which will furthermore play an important role in future to connect quantum computers or atomic clocks into quantum networks. This grant will allow purchasing a mode-locked, picosecond laser, which is required to initialize cryogenically-cooled rare-earth-ion doped crystals for the storage of quantum states encoded into a large number of photons in many spectral channels. These so-called quantum memories form key ingredients of quantum repeaters and networks, and need urgent improvement. The laser will remove an important bottleneck that currently impacts further developments, i.e. the problem of translating spectral multipleximg from the classical (telecommunication) world into quantum communications. If acquired timely, it will seed our long-term aim of provable secure communication across the North American continent. In addition to creating highly qualified personnel at various career levels and advancing the fields of quantum optics and quantum communication, our research, through the acquisition of this laser, will ensure that Canada, after a lot of investment into quantum communication during the past decade, remains competitive in this important area.