Precise and Robust Control Operations for Spin Qubits in Diamond-NV Centers

钻石-NV中心是最有前途的固态量子比特之一，因为它结合了自旋的主要优势（有限的希尔伯特空间，出色的可控性和长相干时间）与光学量子比特的优势（初始化和单量子比特读出）。实现这种潜力的要求之一是实现作用于量子位的逻辑门操作。这些运算必须精确，即它们必须尽可能接近理论上所需的酉变换。同时，它们必须是稳健的，即它们必须保持精确，即使实验参数偏离其理想值。在这个项目中，我们将开发实验和理论技术，以有效地实现对NV中心电子自旋的任意控制操作。这些操作将针对精度和鲁棒性进行优化，即，它们将对控制参数（如微波场的相位和幅度）的不希望的变化不敏感。为此，我们将借鉴相关领域，特别是核磁共振领域取得的成果。该项目的第二个目标是通过将系统参数的最佳选择与量子比特编码和动态解耦等主动措施相结合，延长NV中心中量子信息的寿命。

The diamond-NV center is among the most promising solid-state qubits, since it combines the main strengths of spins (limited Hilbert space, excellent controllability, and long coherence times) with those of optical qubits (initialization and single-qubit readout). One of the requirements for realizing this potential is the implementation of logical gate operations acting on the qubits. These operations must be precise, i.e. they must be as close as possible to the theoretically required unitary transformation. At the same time, they must be robust, i.e. they must remain precise, even if the experimental parameters deviate from their ideal values. In this project, we will develop experimental and theoretical techniques for efficiently implementing arbitrary control operations on the electron spins of the NV center. These operations will be optimized for precision and robustness, i.e. they will be insensitive to unwanted variations of control parameters like phase and amplitude of the microwave field. For this purpose, we will draw on the results achieved in related fields, especially nuclear magnetic resonance. The second goal of this project is to extend the lifetime of quantum information in NV centers by combining an optimal choice of system parameters with qubit encoding and active measures like dynamic decoupling.