论文标题
使用数字支持操作改进相估计
Improving phase estimation using the number-conserving operations
论文作者
论文摘要
我们提出了一种理论方案，通过使用非经典输入状态在马赫德尔干涉仪中通过均衡检测来提高相位测量的分辨率和精度，该态通过应用数字连接的产品（GSP）操作（saa^{†}+ta^{†} {†} a）^2^2^2^2^2^2^2^2^2^2^2^2^2^2+真空（TMSV）状态。通过平均光子数（APN），抗束效应和两种模式挤压的度，研究了所提出的GSP-TMSV的非经典特性。特别是，我们的结果表明，高阶M GSP操作和较小的参数s都可以增加总APN，从而改善量子Fisher信息。此外，我们还比较了方案与先前的光子减法/加法方案之间有和没有光子损失的相测量精度。发现我们的方案，尤其是对于S = 0的情况，即使在存在光子损失的情况下，也可以通过增强的相位分辨率和灵敏度进行最佳性能。有趣的是，如果没有损失，我们的计划始终可以超越标准的量子噪声限制（SQL），而当S = 0.5,1的总APN较小时，甚至可以实现Heisenberg限制（HL）。但是，在存在光子损失的情况下，无法击败HL，但是SQL仍然可以克服，特别是在较大的总APN机制中。我们在这里的结果可以在量子计量学中找到重要的应用。
We propose a theoretical scheme to improve the resolution and precision of phase measurement with parity detection in the Mach-Zehnder interferometer by using a nonclassical input state which is generated by applying a number-conserving generalized superposition of products (GSP) operation, (saa^{†}+ta^{†}a)^{m} with s^2+t^2=1, on two-mode squeezed vacuum (TMSV) state. The nonclassical properties of the proposed GSP-TMSV are investigated via average photon number (APN), anti-bunching effect, and degrees of two-mode squeezing. Particularly, our results show that both higher-order m GSP operation and smaller parameter s can increase the total APN, which leads to the improvement of quantum Fisher information. In addition, we also compare the phase measurement precision with and without photon losses between our scheme and the previous photon subtraction/addition schemes. It is found that our scheme, especially for the case of s=0, has the best performance via the enhanced phase resolution and sensitivity when comparing to those previous schemes even in the presence of photon losses. Interestingly, without losses, the standard quantum-noise limit (SQL) can always be surpassed in our our scheme and the Heisenberg limit (HL) can be even achieved when s=0.5,1 with small total APNs. However, in the presence of photon losses, the HL cannot be beaten, but the SQL can still be overcome particularly in the large total APN regimes. Our results here can find important applications in quantum metrology.
