Center for Spintronics and Quantum Computation, University of California, Santa Barbara, CA 93106, USA.
Science. 2009 Dec 11;326(5959):1520-2. doi: 10.1126/science.1181193.
Two-level systems are at the core of numerous real-world technologies such as magnetic resonance imaging and atomic clocks. Coherent control of the state is achieved with an oscillating field that drives dynamics at a rate determined by its amplitude. As the strength of the field is increased, a different regime emerges where linear scaling of the manipulation rate breaks down and complex dynamics are expected. By calibrating the spin rotation with an adiabatic passage, we have measured the room-temperature "strong-driving" dynamics of a single nitrogen vacancy center in diamond. With an adiabatic passage to calibrate the spin rotation, we observed dynamics on sub-nanosecond time scales. Contrary to conventional thinking, this breakdown of the rotating wave approximation provides opportunities for time-optimal quantum control of a single spin.
两层系统是许多现实世界技术的核心，如磁共振成像和原子钟。通过一个振荡场来实现对状态的相干控制，该场的驱动动力学的速率由其幅度决定。随着场强的增加，出现了一个不同的状态，其中操纵速率的线性标度失效，预期会出现复杂的动力学。通过用绝热通道对自旋旋转进行校准，我们已经测量了金刚石中单个氮空位中心的室温“强驱动”动力学。通过绝热通道来校准自旋旋转，我们观察到了纳秒级时间尺度上的动力学。与传统的思维方式相反，这种旋转波近似的破坏为单自旋的时间最优量子控制提供了机会。
