Department of Physics, MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Department of Physics, Harvard University, Cambridge, MA 02138, USA.
Science. 2023 Jun 30;380(6652):1381-1384. doi: 10.1126/science.adg9500. Epub 2023 Jun 29.
Quantum scrambling describes the spreading of information into many degrees of freedom in quantum systems, such that the information is no longer accessible locally but becomes distributed throughout the system. This idea can explain how quantum systems become classical and acquire a finite temperature, or how in black holes the information about the matter falling in is seemingly erased. We probe the exponential scrambling of a multiparticle system near a bistable point in phase space and utilize it for entanglement-enhanced metrology. A time-reversal protocol is used to observe a simultaneous exponential growth of both the metrological gain and the out-of-time-order correlator, thereby experimentally verifying the relation between quantum metrology and quantum information scrambling. Our results show that rapid scrambling dynamics capable of exponentially fast entanglement generation are useful for practical metrology, resulting in a 6.8(4)-decibel gain beyond the standard quantum limit.
量子混叠描述了信息在量子系统中扩展到多个自由度的现象，使得信息不再能够在局部访问，而是分布在整个系统中。这个概念可以解释量子系统如何变得经典并获得有限的温度，或者在黑洞中，关于落入其中的物质的信息是如何被抹去的。我们探测了多粒子系统在相空间中的双稳态附近的指数混叠，并利用它进行增强纠缠的计量学。我们使用时间反转协议观察到计量增益和非时序相关函数同时呈指数增长，从而实验验证了量子计量学和量子信息混叠之间的关系。我们的结果表明，能够快速产生指数纠缠的混叠动力学对于实际计量学是有用的，可实现超出标准量子极限 6.8(4)分贝的增益。
