1. How many invariant polynomials are needed to decide local unitary equivalence of qubit states?
- Author
-
Michał Oszmaniec, Adam Sawicki, and Tomasz Maciążek
- Subjects
Density matrix ,Quantum Physics ,Pure mathematics ,FOS: Physical sciences ,Statistical and Nonlinear Physics ,Mathematical Physics (math-ph) ,Quantum entanglement ,Unitary state ,Reduction procedure ,Qubit ,Invariant (mathematics) ,Quantum Physics (quant-ph) ,Mathematical Physics ,Symplectic geometry ,Quantum computer ,Mathematics - Abstract
Given L-qubit states with the fixed spectra of reduced one-qubit density matrices, we find a formula for the minimal number of invariant polynomials needed for solving local unitary (LU) equivalence problem, that is, problem of deciding if two states can be connected by local unitary operations. Interestingly, this number is not the same for every collection of the spectra. Some spectra require less polynomials to solve LU equivalence problem than others. The result is obtained using geometric methods, i.e. by calculating the dimensions of reduced spaces, stemming from the symplectic reduction procedure., 22 pages
- Published
- 2013
- Full Text
- View/download PDF