arXivDaily arXiv每日学术速递 周一至周五更新
arXiv quant-ph/0612080quant-ph
收藏

损耗对最大纠缠态相位测量精度的限制

Loss-Induced Limits to Phase Measurement Precision with Maximally Entangled States

Mark A. Rubin, Sumanth Kaushik

摘要:

损耗的存在限制了使用最大纠缠态(也称为NOON态)进行相位测量的方法的精度。使用一个简单的分束器模型的损失的计算表明,对于所有的非零值L的损失,相位测量精度降低与纠缠光子的N足够大的数量N的增加。对于高于约0.785的临界值的L,对于所有N值,相位测量精度随着N的增加而降低。对于接近零的L,相位测量精度随着N的增加而提高,直到在N大约等于2.218/L时达到的大约1.018 L弧度的极限精度,并且随着N增加超过该值而降低。本文还研究了在光子总数N_T固定的情况下多次测量的相位测量精度。对于高于约0.586的临界值的L,利用NOON态可获得的相位测量精度与通过使用未纠缠相干态的常规方法可获得的相位测量精度的比率随着N(在单个测量中采用的纠缠光子的数目)的增加而降低,对于N的所有值。当L接近零时,通过在每次测量中使用约N=1.279/L的纠缠光子来优化该比率,得到约1.340 sqrt(L/N_T)弧度的精度。

英文摘要:

The presence of loss limits the precision of an approach to phase measurement using maximally entangled states, also referred to as NOON states. A calculation using a simple beam-splitter model of loss shows that, for all nonzero values L of the loss, phase measurement precision degrades with increasing number N of entangled photons for N sufficiently large. For L above a critical value of approximately 0.785, phase measurement precision degrades with increasing N for all values of N. For L near zero, phase measurement precision improves with increasing N down to a limiting precision of approximately 1.018 L radians, attained at N approximately equal to 2.218/L, and degrades as N increases beyond this value. Phase measurement precision with multiple measurements and a fixed total number of photons N_T is also examined. For L above a critical value of approximately 0.586, the ratio of phase measurement precision attainable with NOON states to that attainable by conventional methods using unentangled coherent states degrades with increasing N, the number of entangled photons employed in a single measurement, for all values of N. For L near zero this ratio is optimized by using approximately N=1.279/L entangled photons in each measurement, yielding a precision of approximately 1.340 sqrt(L/N_T) radians.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑