physical setup and in Sec. \[sec:methodology\] our computational approach. Sec. \[sec:few\_body\] is dedicated to a detailed study of a few-body mixture. Sec. \[sec:few\_body\_MF\] provides intuitive insights in the framework of the mean-field approximation, while Sec. \[sec:few\_body\_MLX\] focuses on correlation and entanglement effects using Multi-Layer Multi-Configuration Time-Dependent Hartree method for bosonic mixtures. The few-to-many-body transition is subject of Sec. \[sec:many\_body\]. Finally, we summarize our findings in Sec. \[sec:conclusions\].

General Framework {#sec:general_setup}
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Our system consists of a particle-imbalanced mixture of two distinguishable bosonic components, denoted by $\sigma \in \{M,I\}$, with $N_M$ particles in the majority component and $N_I$ impurities. All particles are assumed to be of equal mass $m$ and the intra-component interactions are assumed to be zero or negligibly small. The latter can be achieved by means of magnetic Feshbach or confinement induced resonances [@CIR1998; @CIR2000; @CIR2003; @CIR2010; @Feshbach2010]. The majority species interacts with the impurities via s-wave contact interaction of coupling strength $g_{_{MI}}$. The species are confined in separate quasi-1D harmonic traps of different length scales $a_{\sigma}=\sqrt{\hbar/m \omega_{\sigma}}$ with trap frequency $\omega_{\sigma}$ and coinciding trap centers. This can be realized by using two different hyperfine states of $^{87}\rm{Rb}$ and species-dependent optical potentials [@speciestrap2007; @speciestrap2019]. We remark that many of 