  Weak values of quantum observables are a powerful tool for investigating a
broad spectrum of quantum phenomena. For this reason, several methods to
measure them in the laboratory have been proposed. Some of these methods
require weak interactions and postselection, while others are deterministic,
but require statistics over a number of experiments growing exponentially with
the number of measured particles. Here we propose a deterministic
dimension-independent scheme for estimating weak values of arbitrary
observables. The scheme, based on coherently controlled SWAP operations, does
not require prior knowledge of the initial and final states, nor of the
measured observables, and therefore can work with uncharacterized preparation
and measurement devices. As a byproduct, our scheme provides an alternative
expression for two-time states, that is, states describing quantum systems
subject to pre and post-selections. Using this expression, we show that the
controlled-SWAP scheme can be used to estimate weak values for a class of
two-time states associated to bipartite quantum states with positive partial
transpose.
