D1-brane correction to a line operator index

Wilson line operators in the rank $k$ totally symmetric tensor representation of ${\cal N}=4$ $U(N)$ sypersymmetric Yang-Mills theories are expected to be realized as D3-branes expanded in $AdS_5$. Although there is a mismatch between the corresponding line operator indices even in the large $N$ and large $k$ limit, it is possible to calculate the finite $k$ correction on the AdS side as the contribution from D1-branes. We analyze D1-brane fluctuation modes and calculate the leading finite $k$ correction to the line operator index on the AdS side.