POLARIS: high POwer, phase-locked LAseRs for atom InterferometerS

量子技术依赖于量子叠加态的行为。通常希望使用寿命较长的叠加态，因为这样可以获得最大的好处。例如，当测量力、加速度、磁场和电场，或者只是时间的流逝时，长时间的叠加态提供了最高的灵敏度，这是量子传感的关键优势。对于计算，较长的相干时间增加了可用的计算能力。操纵原子（或离子或分子）内部量子态最方便的方法是使用与原子电荷畸变耦合的激光。两个稳定的、低洼的原子状态可以用一对激光束叠加在一起，这对激光束的频率不同于连接这两个状态的微波频率。这被称为拉曼跃迁。两个激光频率之间的微波拍音被转移到原子态的量子叠加态，然后在微波频率上振荡，相位被激光留下印记。为了充分利用量子干涉，人们需要稳定强度的激光——最好是高强度的激光——并且拍音中的相位噪声非常低。对于许多这样的应用，没有合适的激光系统是商用的。这就是我们要解决的问题。M-Squared激光器生产的SolsTis是一种非常稳定的高功率激光器，为开发合适的产品提供了理想的起点。它在近红外范围内（700 nm - 1000 nm）可广泛调谐，因此它可以处理广泛的相关原子，特别是两个主要原子铷和铯。帝国理工学院的研究小组正在利用铷原子中的原子量子相干性开发惯性导航加速度计。这种应用具有挑战性，因为驱动拉曼跃迁的激光器必须结合高功率、极低相位噪声、低漂移以及功率、频率和相位的高敏捷性。我们建议与M-Squared密切合作，开发一种封装激光系统，以优化这些加速度计的性能。这包括定义最佳规范的研究和在商业包中交付这些规范的开发。本提案的目标是定义并生产合适的激光系统，并通过展示高性能来验证它，首先在1轴加速度计中，然后在3轴原型中。该系统将在不依赖卫星网络的新导航方法的背景下进行开发和验证，该方法具有军事和运输应用。然而，由于拉曼跃迁在量子技术中的普遍重要性，它将得到更广泛的应用。其他可能的应用包括地质测量、采矿、超精确时间戳、医学成像和量子信息处理。

Quantum technology relies on the behaviour of quantum superposition states. It is generally desirable to work with longlived superpositions as these give the greatest benefit. For example, when measuring forces, accelerations, magnetic and electric fields, or just the passage of time, long-lived superpositions give the highest sensitivity and that is the key advantage of quantum sensing. For computation, long coherence time increases the available computing power. The most convenient way to manipulate the internal quantum states of an atom (or ion or molecule) is using laser light that couples to the charge distortion of the atom. Two stable, low-lying atomic states can be superposed using a pair of laser beams whose frequencies differ by the microwave frequency linking the two states. This is called a Raman transition. The microwave beat note between the two laser frequencies is transferred to the quantum superposition of atomic states, which then oscillates at the microwave frequency, with the phase impressed by the lasers. To make the most of quantum interference, one needs lasers of stable intensity -- preferably high intensity -- and exceptionally low phase noise in the beat note. For many such applications, no suitable laser system is commercially available. That is the problem we address here. The SolsTis produced by M-Squared Lasers is a very stable, high-power laser, which provides the ideal starting pointfor developing a suitable product. It is broadly-tuneable across the near infrared range (700 nm - 1,000 nm), so it can address a wide range of relevant atoms, particularly the two workhorse atoms rubidium and caesium. The team at Imperial College is developing accelerometers for inertial navigation using atomic quantum coherence in rubidium atoms. This application is challenging as the lasers driving the Raman transition must combine high power, exceptionally low phase noise, low drift, and great agility of power, frequency and phase. We propose to work closely with M-Squared to develop a packaged laser system that optimises the performance of these accelerometers. This involves research to define the optimum specifications and development to deliver those specifications in a commercial package. The goal of the present proposal is to define and then produce a suitable laser system, and to validate it by demonstrating high performance, first in a 1-axis accelerometer and then in a 3-axis prototype.The system will be developed and validated in the context of a new method for navigating without recourse to the satellite network, which has military and transport applications. However, it will be much more widely useful because of the general importance of Raman transitions in quantum technology. Other probable applications include geological surveying, mining, ultra-precise time stamping, medical imaging, and quantum information processing.