(英) |
For the development of quantum information technology, it is essential to provide a method to efficiently estimate the quantum state (parameter). However, the optimal measurement for estimating an unknown parameter depends on the parameter itself. To surmount this problem, the adaptive quantum state estimation (AQSE) scheme was advocated. In AQSE, for each measurement, the value of parameter is estimated and then the measurement system is optimized for the estimated value.
In our demonstration of AQSE, the estimation speed was limited by half wave plate on mechanical rotator used for the measurement system. Here, we demonstrate AQSE using liquid crystal retarder for the measurement system. We realized a substantial speed-up of estimation time, keeping the accuracy of estimation at the same level. In fact, it took 0.40 second per photon in the previous study, whereas 0.073 second per photon in the present. |