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Numerical radius inequalities for tensor product of operators

Functional Analysis 2024-08-14 v1

Abstract

The two well-known numerical radius inequalities for the tensor product ABA \otimes B acting on HK\mathbb{H} \otimes \mathbb{K}, where AA and BB are bounded linear operators defined on complex Hilbert spaces H\mathbb{H} and K, \mathbb{K}, respectively are, 12ABw(AB)AB \frac{1}{2} \|A\|\|B\| \leq w(A \otimes B) \leq \|A\|\|B\| and w(A)w(B)w(AB)min{w(A)B,w(B)A}.w(A)w(B) \leq w(A \otimes B) \leq \min \{ w(A) \|B\|, w(B) \|A\| \}. In this article we develop new lower and upper bounds for the numerical radius w(AB)w(A \otimes B) of the tensor product ABA \otimes B and study the equality conditions for those bounds.

Keywords

Cite

@article{arxiv.2203.12162,
  title  = {Numerical radius inequalities for tensor product of operators},
  author = {Anirban Sen and Pintu Bhunia and Kallol Paul},
  journal= {arXiv preprint arXiv:2203.12162},
  year   = {2024}
}

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10 pages