Multiqubit UPB: the method of formally orthogonal matrices

@article{Chen2018MultiqubitUT,
  title={Multiqubit UPB: the method of formally orthogonal matrices},
  author={Lin Chen and Dragomir Ž. Đokovi{\'c}},
  journal={Journal of Physics A: Mathematical and Theoretical},
  year={2018},
  volume={51}
}
  • Lin ChenD. Đoković
  • Published 26 January 2018
  • Mathematics
  • Journal of Physics A: Mathematical and Theoretical
We use formal matrices whose entries we view as vector variables taking unit vector values in one-qubit Hilbert spaces of a multiqubit quantum system. We construct many unextendible product bases (UPBs) of new sizes in such systems and provide a new construction of UPBs of n qubits of cardinality n  +  1 when . We also give a new method of constructing multiqubit entangled states with all partial transposes positive. 

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