Abstract
For every possible spectrum of 2N-dimensional density operators, we construct an N-qubit X-state of the same spectrum and maximal genuine multipartite (GM-) concurrence, hence characterizing a global unitary transformation that - constrained to output X-states - maximizes the GM-concurrence of an arbitrary input mixed state of N qubits. We also apply semidefinite programming methods to obtain N-qubit X-states with maximal GM-concurrence for a given purity and to provide an alternative proof of optimality of a recently proposed set of density matrices for the purpose, the so-called XMEMS. Furthermore, we introduce a numerical strategy to tailor a quantum operation that converts between any two given density matrices using a relatively small number of Kraus operators. We apply our strategy to design short operator-sum representations for the transformation between any given N-qubit mixed state and a corresponding X-MEMS of the same purity.
Original language | English (US) |
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Article number | 215304 |
Journal | Journal of Physics A: Mathematical and Theoretical |
Volume | 48 |
Issue number | 21 |
DOIs | |
State | Published - May 29 2015 |
Externally published | Yes |
Keywords
- Entanglement
- Genuine Multipartite Concurrence
- N-qubit X-states
ASJC Scopus subject areas
- Statistical and Nonlinear Physics
- Statistics and Probability
- Modeling and Simulation
- Mathematical Physics
- Physics and Astronomy(all)