<p>This note investigates the symmetric composition <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="162" /> </InlineMediaObject> <EquationSource Format="TEX">\(e^{i\frac{1}{2}(W\omega ){\mathcal {X}}}e^{(Bt)\nabla }e^{i\frac{1}{2}(W\omega ){\mathcal {X}}}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>e</mi> <mrow> <mi>i</mi> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <mrow> <mo stretchy="false">(</mo> <mi>W</mi> <mi>ω</mi> <mo stretchy="false">)</mo> </mrow> <mi mathvariant="script">X</mi> </mrow> </msup> <msup> <mi>e</mi> <mrow> <mo stretchy="false">(</mo> <mi>B</mi> <mi>t</mi> <mo stretchy="false">)</mo> <mi mathvariant="normal">∇</mi> </mrow> </msup> <msup> <mi>e</mi> <mrow> <mi>i</mi> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <mrow> <mo stretchy="false">(</mo> <mi>W</mi> <mi>ω</mi> <mo stretchy="false">)</mo> </mrow> <mi mathvariant="script">X</mi> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation> of the exponentiation of the Hamiltonian operator <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq2.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(\nabla \)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">∇</mi> </math></EquationSource> </InlineEquation> and the operator <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq3.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="135" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathcal {X}}=({\mathcal {X}}_1,\cdots ,{\mathcal {X}}_n)^\prime \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="script">X</mi> <mo>=</mo> <msup> <mrow> <mo stretchy="false">(</mo> <msub> <mi mathvariant="script">X</mi> <mn>1</mn> </msub> <mo>,</mo> <mo>⋯</mo> <mo>,</mo> <msub> <mi mathvariant="script">X</mi> <mi>n</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mo>′</mo> </msup> </mrow> </math></EquationSource> </InlineEquation> with <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq4.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="21" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathcal {X}}_j\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="script">X</mi> <mi>j</mi> </msub> </math></EquationSource> </InlineEquation> being multiplication by the <i>j</i>-th coordinate function for lattice translation matrix <i>B</i> and directional modulation matrix <i>W</i>. We point out that, in the case <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq5.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="88" /> </InlineMediaObject> <EquationSource Format="TEX">\(B=W=I\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>B</mi> <mo>=</mo> <mi>W</mi> <mo>=</mo> <mi>I</mi> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq6.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="99" /> </InlineMediaObject> <EquationSource Format="TEX">\(e^{i\frac{1}{2}\omega {\mathcal {X}}}e^{t\nabla }e^{i\frac{1}{2}\omega {\mathcal {X}}}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>e</mi> <mrow> <mi>i</mi> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <mi>ω</mi> <mi mathvariant="script">X</mi> </mrow> </msup> <msup> <mi>e</mi> <mrow> <mi>t</mi> <mi mathvariant="normal">∇</mi> </mrow> </msup> <msup> <mi>e</mi> <mrow> <mi>i</mi> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <mi>ω</mi> <mi mathvariant="script">X</mi> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation> gives rise to an alternative definition of the operator <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq7.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="55" /> </InlineMediaObject> <EquationSource Format="TEX">\(e^{t\nabla +i\omega {\mathcal {X}}}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>e</mi> <mrow> <mi>t</mi> <mi mathvariant="normal">∇</mi> <mo>+</mo> <mi>i</mi> <mi>ω</mi> <mi mathvariant="script">X</mi> </mrow> </msup> </math></EquationSource> </InlineEquation>, which was originally defined by Folland from the approach of partial differential equation. We further extend the operator <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq7.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="55" /> </InlineMediaObject> <EquationSource Format="TEX">\(e^{t\nabla +i\omega {\mathcal {X}}}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>e</mi> <mrow> <mi>t</mi> <mi mathvariant="normal">∇</mi> <mo>+</mo> <mi>i</mi> <mi>ω</mi> <mi mathvariant="script">X</mi> </mrow> </msup> </math></EquationSource> </InlineEquation> to anisotropic case <InlineEquation ID="IEq9"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq9.gif" Format="GIF" Height="18" Rendition="HTML" Resolution="72" Type="Linedraw" Width="96" /> </InlineMediaObject> <EquationSource Format="TEX">\(e^{(Bt)\nabla +i(W\omega ){\mathcal {X}}}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>e</mi> <mrow> <mo stretchy="false">(</mo> <mi>B</mi> <mi>t</mi> <mo stretchy="false">)</mo> <mi mathvariant="normal">∇</mi> <mo>+</mo> <mi>i</mi> <mo stretchy="false">(</mo> <mi>W</mi> <mi>ω</mi> <mo stretchy="false">)</mo> <mi mathvariant="script">X</mi> </mrow> </msup> </math></EquationSource> </InlineEquation> by setting <InlineEquation ID="IEq10"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq10.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="282" /> </InlineMediaObject> <EquationSource Format="TEX">\(e^{(Bt)\nabla +i(W\omega ){\mathcal {X}}}:=e^{i\frac{1}{2}(W\omega ){\mathcal {X}}}e^{(Bt)\nabla }e^{i\frac{1}{2}(W\omega ){\mathcal {X}}}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>e</mi> <mrow> <mo stretchy="false">(</mo> <mi>B</mi> <mi>t</mi> <mo stretchy="false">)</mo> <mi mathvariant="normal">∇</mi> <mo>+</mo> <mi>i</mi> <mo stretchy="false">(</mo> <mi>W</mi> <mi>ω</mi> <mo stretchy="false">)</mo> <mi mathvariant="script">X</mi> </mrow> </msup> <mo>:</mo> <mo>=</mo> <msup> <mi>e</mi> <mrow> <mi>i</mi> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <mrow> <mo stretchy="false">(</mo> <mi>W</mi> <mi>ω</mi> <mo stretchy="false">)</mo> </mrow> <mi mathvariant="script">X</mi> </mrow> </msup> <msup> <mi>e</mi> <mrow> <mo stretchy="false">(</mo> <mi>B</mi> <mi>t</mi> <mo stretchy="false">)</mo> <mi mathvariant="normal">∇</mi> </mrow> </msup> <msup> <mi>e</mi> <mrow> <mi>i</mi> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <mrow> <mo stretchy="false">(</mo> <mi>W</mi> <mi>ω</mi> <mo stretchy="false">)</mo> </mrow> <mi mathvariant="script">X</mi> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation> and relate it to an initial problem of PDE. Finally, we focus on the operator <InlineEquation ID="IEq11"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq11.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="207" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathcal {R}}_r e^{i\frac{1}{2}(W\omega ){\mathcal {X}}}e^{(Bt)\nabla }e^{i\frac{1}{2}(W\omega ){\mathcal {X}}}{\mathcal {D}}_A\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="script">R</mi> <mi>r</mi> </msub> <msup> <mi>e</mi> <mrow> <mi>i</mi> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <mrow> <mo stretchy="false">(</mo> <mi>W</mi> <mi>ω</mi> <mo stretchy="false">)</mo> </mrow> <mi mathvariant="script">X</mi> </mrow> </msup> <msup> <mi>e</mi> <mrow> <mo stretchy="false">(</mo> <mi>B</mi> <mi>t</mi> <mo stretchy="false">)</mo> <mi mathvariant="normal">∇</mi> </mrow> </msup> <msup> <mi>e</mi> <mrow> <mi>i</mi> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <mrow> <mo stretchy="false">(</mo> <mi>W</mi> <mi>ω</mi> <mo stretchy="false">)</mo> </mrow> <mi mathvariant="script">X</mi> </mrow> </msup> <msub> <mi mathvariant="script">D</mi> <mi>A</mi> </msub> </mrow> </math></EquationSource> </InlineEquation> with rotation <InlineEquation ID="IEq12"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq12.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="23" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathcal {R}}_r\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="script">R</mi> <mi>r</mi> </msub> </math></EquationSource> </InlineEquation> and nonsingular dilation <InlineEquation ID="IEq13"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq13.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="26" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathcal {D}}_A\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="script">D</mi> <mi>A</mi> </msub> </math></EquationSource> </InlineEquation> and study its coherent group structure by defining the so called ordered symplectic product <InlineEquation ID="IEq14"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq14.gif" Format="GIF" Height="29" Rendition="HTML" Resolution="72" Type="Linedraw" Width="386" /> </InlineMediaObject> <EquationSource Format="TEX">\(\left[ (t,\omega ),({{\tilde{t}}}, {\tilde{\omega }})\right] ^A_{B,W}:=t^\prime \left( B^\prime (A^\prime )^{-1}W\right) {\tilde{\omega }}- {{\tilde{t}}}^\prime \left( B^\prime A^\prime W\right) \omega \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msubsup> <mfenced close="]" open="["> <mrow> <mo stretchy="false">(</mo> <mi>t</mi> <mo>,</mo> <mi>ω</mi> <mo stretchy="false">)</mo> </mrow> <mo>,</mo> <mrow> <mo stretchy="false">(</mo> <mover accent="true"> <mi>t</mi> <mo stretchy="false">~</mo> </mover> <mo>,</mo> <mover accent="true"> <mi>ω</mi> <mo stretchy="false">~</mo> </mover> <mo stretchy="false">)</mo> </mrow> </mfenced> <mrow> <mi>B</mi> <mo>,</mo> <mi>W</mi> </mrow> <mi>A</mi> </msubsup> <mo>:</mo> <mo>=</mo> <msup> <mi>t</mi> <mo>′</mo> </msup> <mfenced close=")" open="("> <msup> <mi>B</mi> <mo>′</mo> </msup> <msup> <mrow> <mo stretchy="false">(</mo> <msup> <mi>A</mi> <mo>′</mo> </msup> <mo stretchy="false">)</mo> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> <mi>W</mi> </mfenced> <mover accent="true"> <mi>ω</mi> <mo stretchy="false">~</mo> </mover> <mo>-</mo> <msup> <mrow> <mover accent="true"> <mi>t</mi> <mo stretchy="false">~</mo> </mover> </mrow> <mo>′</mo> </msup> <mfenced close=")" open="("> <msup> <mi>B</mi> <mo>′</mo> </msup> <msup> <mi>A</mi> <mo>′</mo> </msup> <mi>W</mi> </mfenced> <mi>ω</mi> </mrow> </math></EquationSource> </InlineEquation> for the slice vectors <InlineEquation ID="IEq15"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq15.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="39" /> </InlineMediaObject> <EquationSource Format="TEX">\((t,\omega )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>t</mi> <mo>,</mo> <mi>ω</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq16"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq16.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="39" /> </InlineMediaObject> <EquationSource Format="TEX">\(({\tilde{t}},\tilde{\omega })\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mover accent="true"> <mi>t</mi> <mo stretchy="false">~</mo> </mover> <mo>,</mo> <mover accent="true"> <mi>ω</mi> <mo stretchy="false">~</mo> </mover> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> from the vectors <InlineEquation ID="IEq17"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq17.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="74" /> </InlineMediaObject> <EquationSource Format="TEX">\((r,t,\omega ,A)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>r</mi> <mo>,</mo> <mi>t</mi> <mo>,</mo> <mi>ω</mi> <mo>,</mo> <mi>A</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq18"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq18.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="74" /> </InlineMediaObject> <EquationSource Format="TEX">\(({\tilde{r}},{\tilde{t}},\tilde{\omega },{\tilde{A}})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mover accent="true"> <mi>r</mi> <mo stretchy="false">~</mo> </mover> <mo>,</mo> <mover accent="true"> <mi>t</mi> <mo stretchy="false">~</mo> </mover> <mo>,</mo> <mover accent="true"> <mi>ω</mi> <mo stretchy="false">~</mo> </mover> <mo>,</mo> <mover accent="true"> <mi>A</mi> <mo stretchy="false">~</mo> </mover> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> in <InlineEquation ID="IEq19"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41_2025_10158_Article_IEq19.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="197" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathbb {H}}:={\mathbb {R}}\times ({\mathbb {R}}^n\times {\mathbb {R}}^n)\times {\mathbb {M}}^{n\times n}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="double-struck">H</mi> <mo>:</mo> <mo>=</mo> <mi mathvariant="double-struck">R</mi> <mo>×</mo> <mrow> <mo stretchy="false">(</mo> <msup> <mrow> <mi mathvariant="double-struck">R</mi> </mrow> <mi>n</mi> </msup> <mo>×</mo> <msup> <mrow> <mi mathvariant="double-struck">R</mi> </mrow> <mi>n</mi> </msup> <mo stretchy="false">)</mo> </mrow> <mo>×</mo> <msup> <mrow> <mi mathvariant="double-struck">M</mi> </mrow> <mrow> <mi>n</mi> <mo>×</mo> <mi>n</mi> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation>, respectively.</p>

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Symmetric Composition of Exponential Type Operators

  • Qiuhui Chen,
  • Tao Qian

摘要

This note investigates the symmetric composition \(e^{i\frac{1}{2}(W\omega ){\mathcal {X}}}e^{(Bt)\nabla }e^{i\frac{1}{2}(W\omega ){\mathcal {X}}}\) e i 1 2 ( W ω ) X e ( B t ) e i 1 2 ( W ω ) X of the exponentiation of the Hamiltonian operator \(\nabla \) and the operator \({\mathcal {X}}=({\mathcal {X}}_1,\cdots ,{\mathcal {X}}_n)^\prime \) X = ( X 1 , , X n ) with \({\mathcal {X}}_j\) X j being multiplication by the j-th coordinate function for lattice translation matrix B and directional modulation matrix W. We point out that, in the case \(B=W=I\) B = W = I , \(e^{i\frac{1}{2}\omega {\mathcal {X}}}e^{t\nabla }e^{i\frac{1}{2}\omega {\mathcal {X}}}\) e i 1 2 ω X e t e i 1 2 ω X gives rise to an alternative definition of the operator \(e^{t\nabla +i\omega {\mathcal {X}}}\) e t + i ω X , which was originally defined by Folland from the approach of partial differential equation. We further extend the operator \(e^{t\nabla +i\omega {\mathcal {X}}}\) e t + i ω X to anisotropic case \(e^{(Bt)\nabla +i(W\omega ){\mathcal {X}}}\) e ( B t ) + i ( W ω ) X by setting \(e^{(Bt)\nabla +i(W\omega ){\mathcal {X}}}:=e^{i\frac{1}{2}(W\omega ){\mathcal {X}}}e^{(Bt)\nabla }e^{i\frac{1}{2}(W\omega ){\mathcal {X}}}\) e ( B t ) + i ( W ω ) X : = e i 1 2 ( W ω ) X e ( B t ) e i 1 2 ( W ω ) X and relate it to an initial problem of PDE. Finally, we focus on the operator \({\mathcal {R}}_r e^{i\frac{1}{2}(W\omega ){\mathcal {X}}}e^{(Bt)\nabla }e^{i\frac{1}{2}(W\omega ){\mathcal {X}}}{\mathcal {D}}_A\) R r e i 1 2 ( W ω ) X e ( B t ) e i 1 2 ( W ω ) X D A with rotation \({\mathcal {R}}_r\) R r and nonsingular dilation \({\mathcal {D}}_A\) D A and study its coherent group structure by defining the so called ordered symplectic product \(\left[ (t,\omega ),({{\tilde{t}}}, {\tilde{\omega }})\right] ^A_{B,W}:=t^\prime \left( B^\prime (A^\prime )^{-1}W\right) {\tilde{\omega }}- {{\tilde{t}}}^\prime \left( B^\prime A^\prime W\right) \omega \) ( t , ω ) , ( t ~ , ω ~ ) B , W A : = t B ( A ) - 1 W ω ~ - t ~ B A W ω for the slice vectors \((t,\omega )\) ( t , ω ) and \(({\tilde{t}},\tilde{\omega })\) ( t ~ , ω ~ ) from the vectors \((r,t,\omega ,A)\) ( r , t , ω , A ) and \(({\tilde{r}},{\tilde{t}},\tilde{\omega },{\tilde{A}})\) ( r ~ , t ~ , ω ~ , A ~ ) in \({\mathbb {H}}:={\mathbb {R}}\times ({\mathbb {R}}^n\times {\mathbb {R}}^n)\times {\mathbb {M}}^{n\times n}\) H : = R × ( R n × R n ) × M n × n , respectively.