Proposal for a Sensitive Search for the Electric Dipole Moment of the Electron with Matrix-Isolated Radicals

We propose using matrix-isolated paramagnetic diatomic molecules to search for the electric dipole moment of the electron ($e\mathrm{EDM}$). As was suggested by Shapiro in 1968, the $e\mathrm{EDM}$ leads to a magnetization of a sample in the external electric field. In a typical condensed matter experiment, the effective field on the unpaired electron is of the same order of magnitude as the laboratory field, typically about ${10}^5\mathrm{V}/\mathrm{cm}$. We exploit the fact that the effective electric field inside heavy polar molecules is on the order of ${10}^{10}\mathrm{V}/\mathrm{cm}$. This leads to a huge enhancement of the Shapiro effect. Statistical sensitivity of the proposed experiment may allow one to improve the current limit on $e\mathrm{EDM}$ by 3 orders of magnitude in a few hours accumulation time.

Figure 1

Scheme of searching for EDM of an electron with diatomic radicals embedded in a matrix of rare-gas atoms. A polarizing electric field $E$ is applied to the matrix. As a result, molecular $CP$-violating magnetic moments ${\mu }^{CP}$ become oriented and generate ultraweak magnetic field $B^{CP}$. By measuring $B^{CP}$, one places constraints on $e\mathrm{EDM}$.