Al-Rashed–Zegarliński conjecture on monotonicity of the Schatten quadratic form

From papers

Let HH be a complex Hilbert space and let B(H)B(H) denote the linear operators on HH. For 1<p<1<p<\infty, define the Schatten norm by Tp=(TrTp)1/p\|T\|_p=(\operatorname{Tr}|T|^p)^{1/p}. For A,B,DB(H)A,B,D\in B(H), define the quadratic form

A,BD:=sts=t=0D+sA+tBp2.\langle A,B\rangle_D:=\left.\partial_s\partial_t\right|_{s=t=0}\|D+sA+tB\|_p^2.

Al-Rashed–Zegarliński's quadratic-form conjecture. For every completely positive trace-preserving map ϕ\phi on B(H)B(H) and all A,B,DB(H)A,B,D\in B(H),

ϕ(A),ϕ(A)ϕ(D)A,AD.\langle\phi(A),\phi(A)\rangle_{\phi(D)}\leq\langle A,A\rangle_D.

The source introduces this as a special case of a conjecture concerning monotonicity of a noncommutative Luxembourg norm. The supplied text does not state whether this conjecture is proved or disproved, so its status remains open here.

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Sources & referencesView supporting material

Primary source

Haonan Zhang, “Some convexity and monotonicity results of trace functionals”, arXiv:2108.05785 (2023).

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