Modified anisotropic Calderón conjecture at nonzero frequency

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Let Ω⊂Rn\Omega \subset \mathbb{R}^n, n≥3n \geq 3, be a bounded domain with smooth boundary, and let γ1,γ2\gamma_1,\gamma_2 be bounded measurable anisotropic conductivities on Ω‾\overline{\Omega}. Let Λγ,λ\Lambda_{\gamma,\lambda} denote the Dirichlet-to-Neumann map at frequency λ\lambda, and let SDiff⁡(Ω‾)\operatorname{SDiff}(\overline{\Omega}) denote the diffeomorphisms of Ω‾\overline{\Omega} with ∣det⁡DΨ∣=1|\det D\Psi|=1. Assume that λ≠0\lambda\ne 0 is fixed and does not belong to the Dirichlet spectrum of LγjL_{\gamma_j} for j=1,2j=1,2.

Modified anisotropic Calderón conjecture at nonzero frequency. If

Λγ1,λ=Λγ2,λ,\Lambda_{\gamma_1,\lambda}=\Lambda_{\gamma_2,\lambda},

then γ1\gamma_1 and γ2\gamma_2 are equal up to isometry: there exists Ψ∈SDiff⁡(Ω‾)\Psi\in\operatorname{SDiff}(\overline{\Omega}) such that

γ2=Ψ∗γ1.\gamma_2=\Psi_*\gamma_1.

This modifies the usual anisotropic Calderón conjecture because at nonzero frequency the relevant gauge consists of volume-preserving diffeomorphisms. The supplied text gives no resolution evidence, so the conjecture is recorded as open.

References

Primary source

Thierry Daudé, Bernard Helffer, Niky Kamran and François Nicoleau, “Global counterexamples to uniqueness for a Calderón problem with C^k conductivities”, arXiv:2406.14063 (2024).

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