Compact Terahertz Clock

紧凑型太赫兹时钟

• 批准号: EP/Y004361/1
• 负责人: Matthias Keller
• 金额: $ 48.65万
• 依托单位: University of Sussex
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FY004361%2F1
• 关键词: Compact; Terahertz; Clock

In recent decades, atomic clocks have developed from being solely research instruments to indispensable and infrastructure-critical devices. Atomic clocks are now widely used in Global Navigation Satellite Systems (GNSS), data centres, power and mobile networks, financial markets for transaction time stamping, and research and development. Presently, many applications requiring high-precision timing rely on GNSS signals. However, this makes crucial infrastructure vulnerable to GNSS tampering and failure, with significant socio-economic consequences. Therefore, local high-performance atomic clocks are needed to safeguard against this. Other applications need to function in a GNSS-denied environment such as the navigation of submarines or electronic warfare and other security situations. Clock performance beyond GNSS capability is also required for state-of-the-art scientific research and advanced timekeeping.Current portable clocks currently have limited stability and accuracy or are too large and sensitive for applications on mobile platforms. While there has been immense progress in the miniaturisation of the laser systems and spectroscopy units for high-precision optical atomic clocks there are still two main challenges to overcome: The reference laser that requires a high-finesse optical cavity and the optical-frequency comb (OFC) that is required to convert the optical reference signal to a usable electronic signal.Here we propose to employ Raman transitions to create a highly stable and accurate atomic clock. In contrast to optical atomic clocks, the atomic reference stability is not transferred to the frequency of a single laser but is encoded in the frequency difference between two Raman lasers. This significantly relaxes requirements on the OFC and the optical cavity for the clock lasers.For the realisation of a THz-clock, we propose using calcium ions trapped in an RF ion trap and the Raman transition between the D3/2-level and the D5/2-level. The frequency splitting between these two states is 1.819 THz and the expected fractional frequency accuracy of the clock is better than 10-14 (systematic accuracy better than 1e-15) with a 20-litre form factor, significantly smaller than current optical clock systems.Due to its high accuracy in conjunction with small SWAP as well as robustness, this novel clock is exceptionally fit for applications on mobile platforms and in locations with low environmental control. Such portability, makes it particularly well suited for applications in the defence and security sector and as GNNS holdover clocks for telecom and utility networks as well as data centres and financial markets with holdover times of several months. Additionally, it enables novel schemes for frequency dissemination and synchronisation across large-scale telecom networks. Within this project, we will set up the THz-clock with equipment provided by CPI, characterise its performance and test the system in some application-relevant scenarios. CPI will perform environmental testing in their test facility, Leonardo will test the clock's performance on a mobile platform, and BT will investigate next-generation schemes for frequency dissemination and synchronisation across large optical fibre networks.

近几十年来，原子钟已经从单纯的研究仪器发展成为不可或缺的基础设施关键设备。原子钟现在被广泛用于全球导航卫星系统(GNSS)、数据中心、电力和移动网络、用于交易时间戳的金融市场以及研发。目前，许多需要高精度授时的应用都依赖于GNSS信号。然而，这使得关键的基础设施容易受到全球导航卫星系统的篡改和故障的影响，造成重大的社会经济后果。因此，需要本地的高性能原子钟来防范这一点。其他应用程序需要在GNSS被拒绝的环境中运行，例如潜艇导航或电子战和其他安全情况。最先进的科学研究和先进的计时也需要超越GNSS能力的时钟性能。目前，便携式时钟的稳定性和精确度有限，或者对于移动平台上的应用来说太大和太敏感。尽管用于高精度光学原子钟的激光系统和光谱装置的小型化已经取得了巨大的进展，但仍然有两个主要的挑战需要克服：需要高精度光学腔的参考激光器和将光学参考信号转换为可用的电子信号所需的光学频率梳(OFC)。在这里，我们建议使用拉曼跃迁来创建高度稳定和精确的原子钟。与光学原子钟不同的是，原子参考稳定性不是转移到单个激光器的频率上，而是编码在两个拉曼激光器之间的频差中。这大大放宽了时钟激光器对OFC和光腔的要求。为了实现太赫兹时钟，我们建议使用捕获在射频离子陷阱中的钙离子，并在D3/2能级和D5/2能级之间进行拉曼跃迁。这两种状态之间的频率分裂为1.819太赫兹，时钟的预期分数频率精度优于10-14(系统精度优于1E-15)，外形因数为20升，比目前的光学时钟系统小得多。由于其高精度结合小交换和稳健性，这种新型时钟特别适合在移动平台和环境控制较低的场所应用。这种便携性使其特别适合于国防和安全部门的应用，以及作为电信和公用事业网络以及数据中心和金融市场的GNN保持时钟，保持时间为几个月。此外，它还实现了跨大规模电信网络的频率传播和同步的新方案。在这个项目中，我们将使用CPI提供的设备设置太赫兹时钟，测试其性能，并在一些与应用相关的场景中测试系统。CPI将在他们的测试设施中进行环境测试，莱昂纳多将在移动平台上测试时钟的性能，英国电信将研究下一代跨大型光纤网络的频率传播和同步方案。