Optimized dynamical decoupling in a model quantum memory
Optimized dynamical decoupling in a model quantum memory
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DOI：
10.1038/nature07951
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发表时间：
2009-04-23
期刊：
影响因子：
64.8
通讯作者：
Bollinger, John J.
中科院分区：
文献类型：
--
作者：
Biercuk, Michael J.;Uys, Hermann;Bollinger, John J.
任何量子系统，例如量子信息或磁共振中使用的量子系统，都会受到随机相位误差的影响，这会极大地影响所需量子操作或测量的保真度（1）。在量子信息的背景下，已经开发了量子纠错技术来纠正这些错误，但资源需求非常大。因此，如果量子比特（qubit）错误率远低于所谓的容错错误阈值（1），预测为10（-3）-10（-6）的量级，则将促进物理上易处理的量子信息系统的实现。实现这种低错误率的需求促使人们寻找替代策略来抑制量子系统中的失相（2）。在这里，我们通过实验证明了通过应用优化的动态解耦（3-8）脉冲序列，使用能够模拟各种量子比特技术的模型量子系统，量子比特错误率的大规模抑制。我们展示了一个分析得出的脉冲序列（9），UDD，并通过主动，实时实验反馈发现新的序列。后一序列被定制为最大化误差抑制而不需要周围噪声环境的先验知识，并且与其它现有序列（包括基准多脉冲自旋回波（10，11））相比能够抑制数量级的误差。我们的工作包括在现实条件下预测量子比特退相干（12，13）的处理的扩展，对于包含非理想化控制脉冲的任意脉冲序列，实验数据和理论之间产生了很强的一致性。这些结果证明了通过跨各种量子位技术的动态解耦技术的量子位存储器错误抑制的鲁棒性（11，14 -16）。
Any quantum system, such as those used in quantum information or magnetic resonance, is subject to random phase errors that can dramatically affect the fidelity of a desired quantum operation or measurement(1). In the context of quantum information, quantum error correction techniques have been developed to correct these errors, but resource requirements are extraordinary. The realization of a physically tractable quantum information system will therefore be facilitated if qubit (quantum bit) error rates are far below the so-called fault-tolerance error threshold(1), predicted to be of the order of 10(-3)-10(-6). The need to realize such low error rates motivates a search for alternative strategies to suppress dephasing in quantum systems(2). Here we experimentally demonstrate massive suppression of qubit error rates by the application of optimized dynamical decoupling(3-8) pulse sequences, using a model quantum system capable of simulating a variety of qubit technologies. We demonstrate an analytically derived pulse sequence(9), UDD, and find novel sequences through active, real-time experimental feedback. The latter sequences are tailored to maximize error suppression without the need for a priori knowledge of the ambient noise environment, and are capable of suppressing errors by orders of magnitude compared to other existing sequences (including the benchmark multi-pulse spin echo(10,11)). Our work includes the extension of a treatment to predict qubit decoherence(12,13) under realistic conditions, yielding strong agreement between experimental data and theory for arbitrary pulse sequences incorporating nonidealized control pulses. These results demonstrate the robustness of qubit memory error suppression through dynamical decoupling techniques across a variety of qubit technologies(11,14-16).