Efficient universal programmable quantum measurements

被引:38
作者
D'Ariano, GM
Perinotti, P
机构
[1] Dipartimento Fis A Volta, QUIT Grp, I-27100 Pavia, Italy
[2] Northwestern Univ, Ctr Photon Commun & Comp, Dept Elect & Comp Engn, Evanston, IL 60208 USA
关键词
Input states - Positive operators - Qubits - Sampling spaces;
D O I
10.1103/PhysRevLett.94.090401
中图分类号
O4 [物理学];
学科分类号
0702 ;
摘要
A universal programmable detector is a device that can be tuned to perform any desired measurement on a given quantum system, by changing the state of an ancilla. With a finite dimension d for the ancilla only approximate universal programmability is possible, with size d = f(epsilon(-1)) increasing the function of the "accuracy" epsilon(-1). In this Letter we show that, much better than the exponential size known in the literature, one can achieve polynomial size. An explicit example with linear size is also presented. Finally, we show that for covariant measurements exact programmability is feasible.
引用
收藏
页码:1 / 4
页数:4
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