Negativity

The negativity<ref>quant-ph/0102117</ref> 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.

Properties

• Is a convex function of :

• Is an entanglement monotone:

where is an arbitrary LOCC operation over

See also

• Logarithmic negativity

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