非完美探测效率对半设备无关量子随机数扩展的影响

Impact of Imperfect Detection Efficiency on Semi-Device-Independent Quantum Random Number Expansion

半设备无关量子随机数扩展相对于设备无关方案的优势在于不需要量子纠缠,更易于实现,但在实际条件下的可行性受到非完美探测效率限制。文章在二维维度目击不等式中引入探测效率参数,探究非完美探测效率对半设备无关随机数扩展的影响。将未探测事件作为结果保留时,可得在相同维度目击值下较低的探测效率对应的实验中量子态和测量过程蕴含更多的随机性。将未探测事件随机赋值,通过SDP优化算法得到可进行半设备无关随机数扩展的探测效率下界为95.7%。

Compared to the device-independent protocols,the advantage of semi device-independent（ denoted as semi DI） random number expansion is that it doesn’t require quantum entanglement and is thus much easier to implement and test. However,in real circumstances,its feasibility might be limited by detection efficiency. The article introduces the detection efficiency parameter to the two dimensional witness inequality to discover the influence of imperfect detection efficiency on semi DI random number expansion. In the first situation that treats the no-detected events as a result,for the same witness value,we can determine that the corresponding experiment under lower detection efficiency contains more randomness from quantum states and measurements process. In the second situation,by assigning the no-detected events randomly,it is derived that the lower bound of detection efficiency for semi DI random number expansion is 95. 7% according to SDP.