Computing quantum discord is NP-complete

  title={Computing quantum discord is NP-complete},
  author={Yichen Huang},
  journal={New Journal of Physics},
  • Yichen Huang
  • Published 25 May 2013
  • Computer Science, Physics
  • New Journal of Physics
We study the computational complexity of quantum discord (a measure of quantum correlation beyond entanglement), and prove that computing quantum discord is NP-complete. Therefore, quantum discord is computationally intractable: the running time of any algorithm for computing quantum discord is believed to grow exponentially with the dimension of the Hilbert space so that computing quantum discord in a quantum system of moderate size is not possible in practice. As by-products, some… 
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