Optimal Quantum Detection of Symmetric States

對稱量子態的最佳化偵測

周志隆(C.-L. Chou) ； 徐立義(L. Y. Hsu)

《中原學報》 31卷3期 (2003/09) Pp. 161-168

https://doi.org/10.6358/JCYU.200309.0161

摘要

我們考慮平面上三個相等間隔、且非正交的量子位元。任意從此三個量子位元裡選取一個，作爲單一量子位元訊號。其餘的兩個量子位元，則作爲雙量子位元訊號。我們發現此雙量子位元訊號的最佳化的機率算子量測，可以解釋成在四維的Hilben空間裡最佳化的正交量測。此外我們也發現，雙量子位元訊號比之於單量子位元訊號，要有較佳的偵測機率。最後，我們也討論了平面上N個相等間隔、且非正交的量子位元，其衍生出來的訊號的偵測情形。

關鍵字

量子偵測 ； 對稱量子態

並列摘要

Three equally separated nonorthogonal quantum bits that lie on the same plane are prepared for signal processing. One of the qubits is randomly picked as the single-qubit signal. The remaining two qubits then form the two-qubit signal. We find that the optimal probability operator measure for the two-qubit signals can be interpreted as the optimal orthogonal measurement in the four-dimensional Hilbert space of the signal states. We also find that the two-qubit signals have a better detection probability than the single-qubit. Possible generalization to the case of N nonorthogonal qubits is also discussed.

並列關鍵字

quantum detection ； symmetric quantum states