Department of Physics, McGill University, Montreal, Quebec, Canada H3A 2T8.
Département de Physique Théorique, Université de Genève, 1211 Genève, Switzerland.
Phys Rev Lett. 2016 Jan 8;116(1):013603. doi: 10.1103/PhysRevLett.116.013603. Epub 2016 Jan 7.
The Keldysh-ordered full counting statistics is a quasiprobability distribution describing the fluctuations of a time-integrated quantum observable. While it is well known that this distribution can fail to be positive, the interpretation and origin of this negativity has been somewhat unclear. Here, we show how the full counting statistics can be tied to trajectories through Hilbert space, and how this directly connects negative quasiprobabilities to an unusual interference effect. Our findings are illustrated with the example of energy fluctuations in a driven bosonic resonator; we discuss how negative quasiprobability here could be detected experimentally using superconducting microwave circuits.
Keldysh 有序全计数统计是一种描述时间积分量子可观测量涨落的准概率分布。虽然众所周知，这种分布可能不是正的，但这种负性的解释和来源一直有些不清楚。在这里，我们展示了全计数统计如何与通过希尔伯特空间的轨迹联系起来，以及这如何将负准概率直接与一种不寻常的干涉效应联系起来。我们的发现以驱动玻色谐振器中能量涨落的例子来说明；我们讨论了如何使用超导微波电路在实验中检测这里的负准概率。
