We predict that a strong nonreciprocity in the resonance spectra of Dirac
quantum dots can be induced by the Berry phase. The nonreciprocity arises in
relatively weak magnetic fields and is manifest in anomalously large
field-induced splittings of quantum dot resonances which are degenerate at
B=0 due to time-reversal symmetry. This exotic behavior, which is governed by
field-induced jumps in the Berry phase of confined electronic states, is unique
to quantum dots in Dirac materials and is absent in conventional quantum dots.
The effect is strong for gapless Dirac particles and can overwhelm the
B-induced orbital and Zeeman splittings. A finite Dirac mass suppresses the
effect. The nonreciprocity, predicted for generic two-dimensional Dirac
materials, is accessible through Faraday and Kerr optical rotation measurements
and scanning tunneling spectroscopy.Comment: 6 pages, 6 figure
