Nonclassical time correlation functions in continuous quantum measurement

被引:44
作者
Bednorz, Adam [1 ]
Belzig, Wolfgang [2 ]
Nitzan, Abraham [3 ]
机构
[1] Univ Warsaw, Fac Phys, Hoza 69, PL-00681 Warsaw, Poland
[2] Univ Konstanz, Fachbereich Phys, D-78457 Constance, Germany
[3] Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Sch Chem, IL-69978 Tel Aviv, Israel
基金
以色列科学基金会;
关键词
MECHANICS; NOISE; MODEL;
D O I
10.1088/1367-2630/14/1/013009
中图分类号
O4 [物理学];
学科分类号
0702 ;
摘要
A continuous projective measurement of a quantum system often leads to a suppression of the dynamics, known as the Zeno effect. Alternatively, generalized nonprojective, so-called 'weak' measurements can be carried out. Such a measurement is parameterized by its strength parameter that can interpolate continuously between the ideal strong measurement with no dynamics-the strict Zeno effect, and a weak measurement characterized by almost free dynamics but blurry observations. Here we analyze the stochastic properties of this uncertainty component in the resulting observation trajectory. The observation uncertainty results from intrinsic quantum uncertainty, the effect of measurement on the system (backaction) and detector noise. It is convenient to separate the latter, system-independent contribution from the system-dependent uncertainty, and this paper shows how to accomplish this separation. The system-dependent uncertainty is found in terms of a quasi-probability, which, despite its weaker properties, is shown to satisfy a weak positivity condition. We discuss the basic properties of this quasi-probability with special emphasis on its time correlation functions as well as their relationship to the full correlation functions along the observation trajectory, and illustrate our general results with simple examples. We demonstrate a violation of classical macrorealism using the fourth-order time correlation functions with respect to the quasi-probability in the two-level system.
引用
收藏
页数:20
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