Dynamical decoupling leads to improved scaling in noisy quantum metrology

Understand

We consider the usage of dynamical decoupling in quantum metrology, where the joint evolution of system plus environment is described by a Hamiltonian.

• We demonstrate that by ultra-fast unitary control operations acting locally only on system qubits, essentially all kinds of noise can be eliminated.
• This is done in such a way that the desired evolution is reduced by at most a constant factor, leading to Heisenberg scaling.
• The only exception is noise that is generated by the Hamiltonian to be estimated itself.