It has been shown that a chain of unusual vortices can travel in a Josephson sandwich embedded in a dielectric. The limiting velocity of such vortex chain is greater than the limiting velocity of the usual vortex chain by <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\coth (L/\lambda )$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>coth</mo> <mo stretchy="false">(</mo> <mi>L</mi> <mo stretchy="false">/</mo> <mi>λ</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>, where L is the thickness of the sandwich electrodes, <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$\lambda$</EquationSource> <EquationSource Format="MATHML"><math> <mi>λ</mi> </math></EquationSource> </InlineEquation> is the London penetration depth. This makes it much easier to extract radiation into a dielectric, in which the speed of light <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$c_m$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>c</mi> <mi>m</mi> </msub> </math></EquationSource> </InlineEquation> must be less than the velocity of the vortex chain v. Cherenkov radiation from a chain of unusual vortices in the dielectric surrounding the sandwich has been studied. The radiation spectrum of the chain consists of a discrete number of lines at frequencies that are multiples of <InlineEquation ID="IEq4"> <EquationSource Format="TEX">$2\pi v/\Xi$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>2</mn> <mi>π</mi> <mi>v</mi> <mo stretchy="false">/</mo> <mi mathvariant="normal">Ξ</mi> </mrow> </math></EquationSource> </InlineEquation>, where <InlineEquation ID="IEq5"> <EquationSource Format="TEX">$\Xi$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Ξ</mi> </math></EquationSource> </InlineEquation> is the period of the chain. In cases where <InlineEquation ID="IEq6"> <EquationSource Format="TEX">$\Xi$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Ξ</mi> </math></EquationSource> </InlineEquation> is of the order of the size of a solitary vortex or greater, then the main contribution to the radiation occurs at the frequency of the first harmonic. For typical parameters of the sandwich and the chain, the radiation frequency falls in the terahertz range.

Chain of Unusual Radiating Josephson Vortices

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2026年1月23日

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A. S. Malishesvkii,
S. A. Uryupin

摘要

It has been shown that a chain of unusual vortices can travel in a Josephson sandwich embedded in a dielectric. The limiting velocity of such vortex chain is greater than the limiting velocity of the usual vortex chain by $\coth (L/\lambda )$ $coth (L / λ)$ , where L is the thickness of the sandwich electrodes, $\lambda$ $λ$ is the London penetration depth. This makes it much easier to extract radiation into a dielectric, in which the speed of light $c_m$ $c_{m}$ must be less than the velocity of the vortex chain v. Cherenkov radiation from a chain of unusual vortices in the dielectric surrounding the sandwich has been studied. The radiation spectrum of the chain consists of a discrete number of lines at frequencies that are multiples of $2\pi v/\Xi$ $2 π v / Ξ$ , where $\Xi$ $Ξ$ is the period of the chain. In cases where $\Xi$ $Ξ$ is of the order of the size of a solitary vortex or greater, then the main contribution to the radiation occurs at the frequency of the first harmonic. For typical parameters of the sandwich and the chain, the radiation frequency falls in the terahertz range.