The Cost of Remembering

Abstract

In 1961, Rolf Landauer pointed out that resetting a binary memory requires a minimum energy of $k_BT ln(2)$. However, once written, any memory is doomed to loose its content if no action is taken. To avoid memory losses, a refresh procedure is periodically performed. In this work we present a theoretical and experimental study of sub-$k_BT$ system to evaluate the minimum energy required to preserve one bit of information over time. Two main conclusions are drawn: (i) in principle the energetic cost to preserve information for a fixed time duration with a given error probability can be arbitrarily reduced if the refresh procedure is performed often enough; (ii) the Heisenberg uncertainty principle sets an upper bound on the memory lifetime, thus no memory can last forever.