Negativity

The negativity[1] is an entanglement measure which is easy to compute.

The negativity can be defined as:

where:

• is the partial transpose of ρ with respect to subsystem A
• is the trace norm or the sum of the sigular values of the operator X.

An alternative and equivalent definition is the absolute sum of the negative eigenvalues of :

where λ_i are all of the eigenvalues.

See also

• Logarithmic negativity

References

[1] Computable measure of entanglement, G. Vidal and R. F. Werner, Publication Phys. Rev. A 65, 032314 (2002) pre-print