  We define an iterative error-minimizing secret key adapting method for
multicarrier CVQKD. A multicarrier CVQKD protocol uses Gaussian subcarrier
quantum continuous variables (CVs) for the transmission. The proposed method
allows for the parties to reach a given target secret key rate with minimized
error rate through the Gaussian sub-channels by a sub-channel adaption
procedure. The adaption algorithm iteratively determines the optimal transmit
conditions to achieve the target secret key rate and the minimal error rate
over the sub-channels. The solution requires no complex calculations or
computational tools, allowing for easy implementation for experimental CVQKD
scenarios.
