论文标题
使用近似量子状态估算期望值
Estimating expectation values using approximate quantum states
论文作者
论文摘要
我们介绍了$ n $ qubit状态的大约描述，其中包含足够的信息，以估算可观察到的任何可观察到的预期值，而这些精度与可观察到的适当定义的符号的比率相吻合，可观察到的系统数量与系统相同的准备工作$ m $的平方根，而没有明确依赖$ n $ n $ n $。我们描述了一个操作程序，用于构建对状态的大致描述，除了量子状态准备外，还需要单量旋转，然后进行单量度测量。我们表明，按照此过程，该州的最终描述的基数增长为$ 3MN $。我们在Rigetti的量子处理器单元上测试了所提出的方法，该方法具有12、16和25 QUBITS，用于随机状态和随机可观察物，尽管实验性误差，但仍与该理论找到了极好的一致性。
We introduce an approximate description of an $N$-qubit state, which contains sufficient information to estimate the expectation value of any observable to a precision that is upper bounded by the ratio of a suitably-defined seminorm of the observable to the square root of the number of the system's identical preparations $M$, with no explicit dependence on $N$. We describe an operational procedure for constructing the approximate description of the state that requires, besides the quantum state preparation, only single-qubit rotations followed by single-qubit measurements. We show that following this procedure, the cardinality of the resulting description of the state grows as $3MN$. We test the proposed method on Rigetti's quantum processor unit with 12, 16 and 25 qubits for random states and random observables, and find an excellent agreement with the theory, despite experimental errors.
