Target-adapted null transport

Choose $x_B\in U$ with

Choose the departure time and distance so that the entire route and final local probe reading lie within the laboratory. For example, use departure $s_{\mathrm{d}}=3a/4$ and $L<a/8$.

For an integer $n\ge 1$, install

Each site carries a payload register $A_j\cong X$. Prepare $A_1,\dots ,A_n$ in the independent blank state $\omega =|000⟩⟨000|$. Set

At tick $j$, apply SWAP to $A_{j-1}{A}_j$.