<p>We present a new spectral-theoretic derivation of the density of states <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\( \rho \left( \lambda \right) \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>ρ</mi> <mfenced close=")" open="("> <mi>λ</mi> </mfenced> </mrow> </math></EquationSource> </InlineEquation> for the sublaplacian operator on the Heisenberg group <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\mathbb {H}^{n}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi mathvariant="double-struck">H</mi> </mrow> <mi>n</mi> </msup> </math></EquationSource> </InlineEquation>. Our method exploits a fundamental connection between this operator and the magnetic Laplacian operator in <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\( \mathbb {C}^{n}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi mathvariant="double-struck">C</mi> </mrow> <mi>n</mi> </msup> </math></EquationSource> </InlineEquation>, linked via a Fourier transform. While the resolvent kernel for the sublaplacian operator is established from a prior work (and whose consistency with Folland’s fundamental solution is a key validation of its form), our core contribution lies in the direct application of the associated spectral density kernel <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(dE_{\lambda }/d\lambda \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>d</mi> <msub> <mi>E</mi> <mi>λ</mi> </msub> <mo stretchy="false">/</mo> <mi>d</mi> <mi>λ</mi> </mrow> </math></EquationSource> </InlineEquation> to obtain <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\rho \left( \lambda \right) =\gamma _{n}\lambda ^{n}, \gamma _{n}&gt;0\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>ρ</mi> <mfenced close=")" open="("> <mi>λ</mi> </mfenced> <mo>=</mo> <msub> <mi>γ</mi> <mi>n</mi> </msub> <msup> <mi>λ</mi> <mi>n</mi> </msup> <mo>,</mo> <msub> <mi>γ</mi> <mi>n</mi> </msub> <mo>&gt;</mo> <mn>0</mn> </mrow> </math></EquationSource> </InlineEquation> is a constant. This approach provides an independent, <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(L{{}^2}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>L</mi> <mmultiscripts> <mrow /> <mrow /> <mn>2</mn> </mmultiscripts> </mrow> </math></EquationSource> </InlineEquation>-spectral alternative to the harmonic analysis techniques used by Strichartz (J. Fourier Anal. Appl. <b>18</b>, 626–659, <CitationRef CitationID="CR16">2012</CitationRef>) to find the integrated density of states, whose derivative confirms our result. Additionally, we provide a general formula for the integrated density of states of the magnetic Laplacian operator in <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\mathbb {C}^{n}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi mathvariant="double-struck">C</mi> </mrow> <mi>n</mi> </msup> </math></EquationSource> </InlineEquation>, extending Nakamura’s one-dimensional result (Nakamura, J. Funct. Anal. <b>179</b>(1), 136–152, <CitationRef CitationID="CR15">2001</CitationRef>). This work highlights the practical utility of the connection between these two operators, demonstrating that the spectral theory of the Heisenberg sublaplacian operator can be effectively advanced by transferring results from the well-studied context of magnetic Hamiltonians in <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(\mathbb {C} ^{n}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi mathvariant="double-struck">C</mi> </mrow> <mi>n</mi> </msup> </math></EquationSource> </InlineEquation>.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

Density of States for the Sub-Laplacian Operator on Heisenberg Groups

  • Zouhaïr Mouayn

摘要

We present a new spectral-theoretic derivation of the density of states \( \rho \left( \lambda \right) \) ρ λ for the sublaplacian operator on the Heisenberg group \(\mathbb {H}^{n}\) H n . Our method exploits a fundamental connection between this operator and the magnetic Laplacian operator in \( \mathbb {C}^{n}\) C n , linked via a Fourier transform. While the resolvent kernel for the sublaplacian operator is established from a prior work (and whose consistency with Folland’s fundamental solution is a key validation of its form), our core contribution lies in the direct application of the associated spectral density kernel \(dE_{\lambda }/d\lambda \) d E λ / d λ to obtain \(\rho \left( \lambda \right) =\gamma _{n}\lambda ^{n}, \gamma _{n}>0\) ρ λ = γ n λ n , γ n > 0 is a constant. This approach provides an independent, \(L{{}^2}\) L 2 -spectral alternative to the harmonic analysis techniques used by Strichartz (J. Fourier Anal. Appl. 18, 626–659, 2012) to find the integrated density of states, whose derivative confirms our result. Additionally, we provide a general formula for the integrated density of states of the magnetic Laplacian operator in \(\mathbb {C}^{n}\) C n , extending Nakamura’s one-dimensional result (Nakamura, J. Funct. Anal. 179(1), 136–152, 2001). This work highlights the practical utility of the connection between these two operators, demonstrating that the spectral theory of the Heisenberg sublaplacian operator can be effectively advanced by transferring results from the well-studied context of magnetic Hamiltonians in \(\mathbb {C} ^{n}\) C n .