论文标题
具有近距离限制敏感性的广义回声挤压协议，对挤压参数的噪音和变化的强大灵敏度
A generalized echo squeezing protocol with near-Heisenberg limit sensitivity and strong robustness against excess noise and variation in squeezing parameter
论文作者
论文摘要
我们提出了一个广义的回声挤压协议（GESP），作为SchrödingerCat状态协议（SCSP）的概括，挤压参数的值是任意数字而不是PI/2。我们分析表明，在众多的挤压参数上，灵敏度达到了root-2因子内的海森堡极限（HL）。对于大量的颗粒，n，该平台间隔几乎是从零到pi/2的整个范围，并且灵敏度与N的奇偶校验无关。因此，可以在不改变灵敏度的情况下在挤压参数的较大间隔上操作传感器。这与仅适用于很小间隔的常规回声挤压协议（CESP）形成对比。与CESP相反，GESP的灵敏度接近量子cramér-rao在挤压参数的整个范围内结合。 GESP的灵敏度的提高是由于两个参数的组合：相位放大因子（PMF）和噪声放大因子（NAF）。随着挤压参数的值增加，PMF和NAF都会增加，保持PMF/NAF常数的比率，从而在root-2的一个因子内产生HL敏感性的增强。因此，对于挤压参数的广泛值，GESP对过量噪声的鲁棒性很容易超过CESP的稳健性。因此，在实验研究的背景下，在典型的条件下，在超过未频繁的量子投影噪声的情况下，应该有可能实现比CESP高的敏感性增强。最后，我们考虑了GESP对与背景粒子的碰撞的脆弱性，并显示脆弱性与与多余噪声的稳健性之间的平衡如何确定GESP的参数的最佳选择。
We present a generalized echo squeezing protocol (GESP) as a generalization of the Schrödinger cat state protocol (SCSP) with the value of the squeezing parameter being an arbitrary number rather than pi/2. We show analytically that over a broad range of the squeezing parameter the sensitivity reaches the Heisenberg limit (HL) within a factor of root-2. For a large number of particles, N, this plateau interval is almost the whole range from zero to pi/2, and the sensitivity is independent of the parity of N. Therefore, it is possible to operate a sensor over a wide interval of the squeezing parameter without changing the sensitivity. This is to be contrasted with the conventional echo squeezing protocol (CESP) which only works for a very small interval. In contrast to the CESP, the sensitivity of the GESP is close to the quantum Cramér-Rao bound over the whole range of the squeezing parameter. The enhancement in sensitivity for the GESP is due to a combination of two parameters: the phase magnification factor (PMF) and the noise amplification factor (NAF). As the value of the squeezing parameter increases, both PMF and NAF increase, keeping the ratio of PMF/NAF constant, yielding an enhancement of sensitivity at the HL within a factor of root-2. Thus, the robustness of the GESP against excess noise easily exceeds that of the CESP for a broad range of values of the squeezing parameter. As such, in the context of an experimental study, it should be possible to achieve a net enhancement in sensitivity higher than that for the CESP, under typical conditions where the excess noise exceeds the unsqueezed quantum projection noise. Finally, we consider the fragility of the GESP against collisions with background particles, and show how a balance between the fragility and the robustness against excess noise would in practice determine the optimal choice of parameters for the GESP.
