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Helge Jørgen Samuelsen

Publications and source records attributed to Helge Jørgen Samuelsen.

5 recordsLinked to original sources
arXiv2025

Compactness of Fourier concentration operators

We present a sufficient condition on sets $E$ and $F$ in $\mathbb{R}^d$ to ensure compactness of Fourier concentration operators by introducing the notion of sets which are very thin at infinity. We are able to show that if the sets $E$ and $F$ are both very thin at infinity, then the associated Fourier concentration operator is compact on $L^2(\mathbb{R}^d)$. The proof relies on a combination of the Logvinenko-Sereda uncertainty principle together with an uncertainty principle due to Shubin, Vakilian and Wolff. This provides a partial answer to a question posed by Katsnelson and Machluf on truncated Fourier operators.

math.CA↗
arXiv2025

Fourier-Wigner multipliers and the Bochner-Riesz conjecture for Schatten class operators

In this paper we introduce the notion of Fourier-Wigner multipliers for the Schatten class operators $\mathcal{S}^p$, which acts as an extension of classical localisation operators in time-frequency analysis. We establish results about Fourier-Wigner multipliers through convolution with rank-one operators and Werner-Young's inequality. We are also able to prove an equivalence relation for compactly supported Fourier multipliers. This allows us to reformulate the Bochner-Riesz conjecture in terms of Schatten class operators.

math.FA↗
arXiv2024

Fourier restriction for Schatten class operators and functions on phase space

We formulate a variant of Fourier restriction for operators in Schatten classes, where the Fourier-Wigner transform of a bounded operator replaces the Fourier transform of a function. The Fourier-Wigner transform is closely related to the group Fourier transform of the Heisenberg group. The first result shows that Fourier-Wigner restriction for Schatten class operators is equivalent to the restriction of the symplectic Fourier transform of functions on phase space. We deduce various Schatten class results for the quantum Fourier extension operator and answer a conjecture by Mishra and Vemuri concerning the Weyl transform of measures in the affirmative.

math.FA↗
arXiv2024

Decoupling for Schatten class operators in the setting of Quantum Harmonic Analysis

We introduce the notion of decoupling for operators, and prove an equivalence between classical $\ell^qL^p$ decoupling for functions and $\ell^q\mathcal{S}^p$ decoupling for operators on bounded sets in $\mathbb{R}^{2d}$. We also show that the equivalence only depends on the bounded set $Ω$, and not the values of $p,q$ nor the partition of $Ω$. The proof relies on a quantum version of Wiener's division lemma.

math.FA↗