Magnetic Field Dependent Tunneling in Glasses

TL;DR

This paper presents experimental evidence that magnetic fields influence quantum tunneling effects in glasses at very low temperatures, revealing flux-dependent dielectric responses and oscillations.

Contribution

It demonstrates magnetic field effects on tunneling systems in glasses, showing flux periodicity and violation of time reversal symmetry at millikelvin temperatures.

Findings

Dielectric response becomes magnetic field sensitive below 100 mK

Weak magnetic fields lift dielectric saturation

Oscillations observed in dielectric response at low temperatures

Abstract

We report on experiments giving evidence for quantum effects of electromagnetic flux in barium alumosilicate glass. In contrast to expectation, below 100 mK the dielectric response becomes sensitive to magnetic fields. The experimental findings include both, the complete lifting of the dielectric saturation by weak magnetic fields and oscillations of the dielectric response in the low temperature resonant regime. As origin of these effects we suggest that the magnetic induction field violates the time reversal invariance leading to a flux periodicity in the energy levels of tunneling systems. At low temperatures, this effect is strongly enhanced by the interaction between tunneling systems and thus becomes measurable.