open sesame
noun [ C usually singular ] mainly UK uk/ˌəʊ.pən ˈses.ə.mi/ us/ˌoʊ.pən ˈses.ə.mi/
（达到…的）法宝，通行手段，开门咒语
something that makes it very easy to achieve a particular thing
A science degree can be an open sesame to a job in almost any field. 理科学位是可以在几乎所有领域获得一份工作的敲门砖。