Towards diamond light matter quantum interface:development of a multi-qubit quantum register based on paramagnetic color centers in diamond

尽管科学和商业组织，包括IT技术市场的领导者做出了相当大的努力，但创建长距离互连量子寄存器的问题仍然具有挑战性。用于制造量子寄存器的有前途的固态材料之一是金刚石。钻石量子寄存器中的量子比特是通过系统中的电子和核自旋来实现的。 自旋量子态的相干控制由微波场和射频场实现，态的制备和阅读由作用于色心光学跃迁的光场实现。历史上，NV中心首先被提出作为基本量子门。德国和俄罗斯的项目小组为这一方向的发展做出了重要贡献。该项目的科学新奇是在钻石中使用新的顺磁性硅空位色心，以创建在mK温度下工作的高效量子寄存器。所提出的硅空位色心具有显著更长的光学相干时间，并且与现有技术相比，它们在单片金刚石谐振器中的植入将显著提高自旋量子位与光子的界面的效率。同时，基于金刚石中具有反转对称性的第四族元素（Ge，Sn，Pb）的杂质的新光学中心的研究将导致在4K量级的更高温度下操作量子寄存器的可能性。该项目还计划在基于氮空位色心的量子寄存器的“传统”方向上开展工作。所提出的方法的新奇在于使用所谓的“稳定岛”的想法-最近发现的金刚石晶格中的位置，这为放置在这些位置的同位素碳原子的自旋提供了高度的一致性。

The problem of creating interconnected over long distance quantum registers remains challenging, despite the considerable efforts of scientific and commercial organizations, including leaders in the market of IT technologies. One of the promising solid-state materials for creating quantum registers is diamond. Qubits in the diamond quantum register is realized by electronic and nuclear spins in the systems. Coherent control of the quantum states of spins is carried out by microwave and radio-frequency fields, and the preparation and reading of states is realized by optical fields acting on the optical transitions of color centers. Historically, the NV center was proposed first as an elementary quantum gate. A key contribution to the development of this direction was made by the project teams from the German and Russian sides. The scientific novelty of this project is to employ new paramagnetic silicon-vacancy color centers in diamonds to create high efficiency quantum registers operating at mK temperatures. The proposed silicon-vacancy color centers have a significantly longer optical coherence time, and their implantation in monolithic diamond resonators will significantly increase the efficiency of the interface of spin qubits with photons when compared to existing technology. At the same time, the proposed studies of new optical centers based on impurities from the fourth group of elements (Ge, Sn, Pb) with inversion symmetry in diamond will lead to possibility to operate quantum registers at higher temperatures of the order of 4K.The project also plans to carry out work in the "traditional" direction of creating quantum registers based on the nitrogen-vacancy color centers. The novelty of the proposed approach lies in the idea of using the so-called "islands of stability" for this - recently discovered positions in the diamond crystal lattice, which provide a high degree of coherence for the spins of isotopic carbon atoms placed in these positions.