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SJTU Professor Validated the New Uncertain Relationship of Continuous Variables

September 08, 2019      Author: Ma Zhihao

Recently, Professor Ma Zhihao from the School of Mathematical Sciences, Shanghai Jiao Tong University, together with the research team led by Academician Peng KunChi and Professor Su Xiaolong from Shanxi University, made important achievements in quantum information. They are the first that validated the new uncertain relationship of continuous variables through experiments. Their research results were published in the nature research journal npj Quantum Information (influence factor 9.2), with Professor Ma Zhihao being the co-first author.

This collaborative work is of great scientific significance, and can be applied in some important areas of quantum information such as quantum communication and quantum precision measurement.


Heisenberg's original uncertainty relation is related to measurement effect, which is different from the preparation uncertainty relation. However, it has been shown that Heisenberg's error disturbance uncertainty relation is not valid in some cases. We experimentally test the error-tradeoff uncertainty relation by using a continuous-variable Gaussian Einstein-Podolsky-Rosen (EPR)-entangled state. Based on the quantum correlation between the two entangled optical beams, the errors on amplitude and phase quadratures of one EPR optical beam coming from joint measurement are estimated, respectively, which are used to verify the error-tradeoff relation. Especially, the error-tradeoff relation for error-free measurement of one observable is verified in our experiment. We also verify the error-tradeoff relations for nonzero errors and mixed state by introducing loss on one EPR beam. Our experimental results demonstrate that Heisenberg's error-tradeoff relation is violated in some cases for a continuous-variable system, while the Ozawa's and Branciard's relations are valid.


 Translated by Chen Qinqian        Reviewed by Wang Bingyu