Experimental nonclassicality in a causal network without assuming freedom of choice
Emanuele Polino, Davide Poderini, Giovanni Rodari, Iris Agresti, Alessia Suprano, Gonzalo Carvacho, Elie Wolfe, Askery Canabarro, George Moreno, Giorgio Milani,… 展开作者
Emanuele Polino, Davide Poderini, Giovanni Rodari, Iris Agresti, Alessia Suprano, Gonzalo Carvacho, Elie Wolfe, Askery Canabarro, George Moreno, Giorgio Milani, Robert W. Spekkens, Rafael Chaves, Fabio Sciarrino
In a Bell experiment, it is natural to seek a causal account of correlations wherein only a common cause acts on the outcomes. For this causal structure, Bell inequality violations can be explained only if causal dependencies are modelled as intrinsically quantum. There also exists a vast landscape of causal structures beyond Bell that can witness nonclassicality, in some cases without even requiring free external inputs. Here, we undertake a photonic experiment realizing one such example: the triangle causal network, consisting of three measurement stations pairwise connected by common causes and no external inputs. To demonstrate the nonclassicality of the data, we adapt and improve three known techniques: (i) a machine-learning-based heuristic test, (ii) a data-seeded inflation technique generating polynomial Bell-type inequalities and (iii) entropic inequalities. The demonstrated experimental and data analysis tools are broadly applicable paving the way for future networks of growing complexity.
Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas（坎皮纳斯州立大学格莱布·瓦塔金物理研究所）；Perimeter Institute for Theoretical Physics（理论物理前沿研究所）；Department of Physics and Astronomy, University of Waterloo（滑铁卢大学物理与天文学系）；Department of Physics, University of Toronto（多伦多大学物理系）
Experimental investigation of nonclassicality in the simplest scenario via the degrees of freedom of light
Universidade Federal Fluminense（弗鲁米嫩塞联邦大学）；International Iberian Nanotechnology Laboratory (INL)（伊比利亚纳米技术国际实验室）；Instituto Federal do Rio de Janeiro（里约热内卢联邦学院）
International Institute of Physics, Federal University of Rio Grande do Norte（国际物理研究所，北里奥格兰德联邦大学）；Departamento de Física Teórica e Experimental, Federal University of Rio Grande do Norte（理论与实验物理系，北里奥格兰德联邦大学）；Perimeter Institute for Theoretical Physics（理论物理珀蒂默研究所）；Institute for Quantum Computing, University of Waterloo（量子计算研究所，滑铁卢大学）；Inria Paris-Saclay（巴黎萨克雷法国国家信息与自动化研究所）；CPHT, LIX, Ecole polytechnique, Institut Polytechnique de Paris（CPHT, LIX, 巴黎综合理工学院，巴黎理工学院）；Università degli Studi di Pavia, Dipartimento di Fisica, QUIT Group（帕维亚大学，物理系，QUIT小组）；School of Science and Technology, Federal University of Rio Grande do Norte（科学与工程学院，北里奥格兰德联邦大学）
Collective atomic correlations in absorptive optical bistability without adiabatic elimination: exemplifying nonclassicality from a linearized treatment of fluctuations
我们确定了吸收光学双稳中集体原子自由度的非相干谱、压缩特性和二阶关联函数。这是通过在正P表示中的线性化Fokker-Planck方程来实现的，由[H. J. Carmichael，Phys.Rev.A33，3262（1986）]，其不采用绝热消除。我们重点关注弱和强腔内激发的机制，解决好腔和坏腔限制以及集体强耦合的限制。利用与系综耦合的辅助谐振腔对腔内场的绝热消除，通过形成集体发射通道来探测原子关联。我们比较了相应的表达式的前向散射光的实验结果，讨论了稳态半经典双稳态曲线的下分支和上分支之间的关键差异。我们的分析是在远离转折点的稳定状态下进行的，在那里可以自洽地获得解析表达式，表明与经典行为有明显的偏离。
A minimal example of quantum non-classicality without freedom of choice
Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas（坎皮纳斯州立大学格莱巴·瓦塔金物理研究所）；International Institute of Physics, Federal University of Rio Grande do Norte（北里奥格兰德联邦大学国际物理研究所）；School of Science and Technology, Federal University of Rio Grande do Norte（北里奥格兰德联邦大学理学院）
Decoherence without the state: A causal quantum Darwinist approach
Perimeter Institute for Theoretical Physics（perimeter 理论物理研究所）；University of Waterloo（滑铁卢大学）；Center for Theoretical Physics, Polish Academy of Sciences（波兰科学院理论物理中心）
