Casimir torque between two solid birefringent plates across vacuum · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Casimir torque between two solid birefringent plates across vacuum
Plain
Two crystals whose optical properties depend on direction should twist toward alignment because of quantum fluctuations, the Casimir torque. It has been measured with a liquid crystal on a solid crystal, but not between two solid plates across empty space.
Precise · changed · core
Revision 1: Two uniaxial birefringent plates (e.g. calcite, quartz, black phosphorus) at gap $d$ across vacuum, with optic axes at relative angle $\theta$: Lifshitz-type theory predicts torque per area $M(\theta, d) \sim A(d) \sin(2\theta)$, with $A(d)$ set by the anisotropic permittivities. An answer is a measurement of A(d) and the $\sin(2\theta)$ dependence at $d$ below about $1e-4\,\mathrm{cm}$, agreeing with theory using measured permittivity tensors.
Revision 2: Two uniaxial birefringent plates (e.g. calcite, quartz, black phosphorus) at gap $d$ across vacuum, with optic axes at relative angle $\theta$: Lifshitz-type theory predicts torque per area $M(\theta, d) \sim A(d) \sin(2\theta)$, with $A(d)$ set by the anisotropic permittivities. An answer is a measurement of A(d) and the $\sin(2\theta)$ dependence at $d$ below about $10^{-4}\,\mathrm{cm}$, agreeing with theory using measured permittivity tensors.
Settled by
A torsional measurement of the angle- and gap-dependent torque between two solid birefringent plates in vacuum.
Kind
well-posed
Answer type
value
References
(empty)
Literature status
partially-resolved
Status note
The torque between a birefringent crystal and a liquid crystal across a thin solid spacer was measured in 2018 (Somers et al., Nature); a solid-solid vacuum measurement has not been reported.
Posed since
(empty)

Decisions