level repulsion

Level repulsion is the quantum mechanical equivalent to a repulsion effect in oscillators.{{cite journal|last1=Frank|first1=Winfried|last2=von Brentano|first2=Peter|title=Classical analogy to quantum mechanical level repulsion|journal=American Journal of Physics|volume=62|issue=8|year=1994|pages=706–709|issn=0002-9505|doi=10.1119/1.17500}} A system of two coupled oscillators has two natural frequencies. As the coupling strength between the oscillators increases, the lower frequency decreases and the higher increases.{{cite journal|last1=Novotny|first1=Lukas|title=Strong coupling, energy splitting, and level crossings: A classical perspective|journal=American Journal of Physics|volume=78|issue=11|year=2010|pages=1199–1202|issn=0002-9505|doi=10.1119/1.3471177}}