The sequential quantum random access code (QRAC) allows two or more decoders to obtain a desired message with higher success probability than the best classical bounds by appropriately modulating the measurement sharpness. Here, we propose an entanglement-assisted sequential QRAC protocol which can enable device-independent tasks. By relaxing the equal sharpness and mutually unbiased measurement limits, we widen the sharpness modulation region from a one-dimensional interval to a two-dimensional triangle. Then, we demonstrate our scheme experimentally and get more than 27 standard deviations above the classical bound even when both decoders perform approximately projective measurements. We use the observed success probability to quantify the connection among sequential QRAC, measurement sharpness, measurement biasedness, and measurement incompatibility. Finally, we show that our protocol can be applied to sequential device-independent randomness expansion and our measurement strategy can enhance the success probability of decoding the entire input string. Our results may promote a deeper understanding of the relationship among quantum correlation, quantum measurement, and quantum information processing.

中文翻译：

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扩展纠缠辅助顺序量子随机访问码的锐度调制范围：理论，实验和应用

顺序量子随机访问码（QRAC）允许两个或多个解码器通过适当地调制测量清晰度来获得比最佳经典范围具有更高成功概率的期望消息。在这里，我们提出了一个纠缠辅助的顺序QRAC协议，该协议可以启用与设备无关的任务。通过放宽相等的锐度和相互无偏的测量限制，我们将锐度调制区域从一维间隔扩展到了二维三角形。然后，我们通过实验证明了我们的方案，即使两个解码器都执行近似的投影测量，也可以获得超过经典界限的27个以上的标准偏差。我们使用观察到的成功概率来量化顺序QRAC，测量清晰度，测量偏差，和测量不兼容。最后，我们证明了我们的协议可以应用于顺序独立于设备的随机性扩展，并且我们的测量策略可以提高解码整个输入字符串的成功概率。我们的结果可能会加深对量子相关性，量子测量和量子信息处理之间关系的理解。