4 papers
Reflection positivity and a refined index for 2d invertible phases
Nikita Sopenko
We analyze the validity of reflection positivity in the classification of invertible phases of quantum spin systems. We provide a mathematical model in which every 2d invertible st…
Optimal bound on long-range distillable entanglement
Jonah Kudler-Flam, Vladimir Narovlansky, Nikita Sopenko
We prove an upper bound on long-range distillable entanglement in spatial dimensions. Namely, it must decay faster than , where is the distance between entangled regio…
An index for invertible phases of two-dimensional quantum spin systems
Nikita Sopenko
We define an index for invertible phases of two-dimensional fermionic and bosonic quantum spin systems without any additional symmetry. Conjecturally, it provides a microscopic def…
Quantization of the higher Berry curvature and the higher Thouless pump
Adam Artymowicz, Anton Kapustin, Nikita Sopenko
We show that for families of 1d lattice systems in an invertible phase, the cohomology class of the higher Berry curvature can be refined to an integral degree-3 class on the param…