Algebraic metrology: Pretty good states and bounds
  We investigate quantum metrology using a Lie algebraic approach for a class of Hamiltonians, including local and nearest-neighbor interaction Hamiltonians. Using this Lie algebraic formulation, we identify and construct highly symmetric states that admit Heisenberg scaling in precision in the absence of noise, and investigate their performance in the presence of noise. To this aim we perform a numerical scaling analysis, and derive upper bounds on the quantum Fisher information. 
Michalis Skotiniotis and Florian Fr\"owis and Wolfgang D\"ur and   Barbara Kraus
quant-ph