A system for controlling a translocation speed of a molecule through a nanopore may include a fluid chamber containing a solution with a magnetic susceptibility that is different from the magnetic susceptibility of the molecule, a nanopore situated in the fluid chamber, and at least one magnetic component configured to create a magnetic field gradient within the solution to control the translocation speed of a molecule through the nanopore. A system for controlling a translocation speed of a molecule through a nanopore may include a nanopore at least one magnetic component situated to create a magnetic field that causes the molecule to experience a rotational torque as it passes through the nanopore.