Block entanglement in the ground state of the Majumdar-Ghosh model


Proceedings of the 34th Samahang Pisika ng Pilipinas Physics Congress, University of the Philippines Visayas, Iloilo City, 18–21 Aug 2016, SPP-2016-PB-22.


We use matrix product state representations and transfer matrix methods to calculate the reduced density matrix of a block of spins in the ground state of the Majumdar-Ghosh spin chain. The full entanglement spectrum is obtained and the von Neumann entanglement entropy is expressed as a function of block length. We found that the von Neumann entropy increases exponentially fast as the length of the block increases and has a saturation value of Smax = ln 3.