  Optomechanical detectors have reached the standard quantum limit in position
and force sensing where measurement backaction noise starts to be the limiting
factor for the sensitivity. A strategy to circumvent measurement backaction,
and surpass the standard quantum limit, has been suggested by M. Tsang and C.
Caves in Phys. Rev. Lett. 105 123601 (2010). We provide a detailed analysis of
this method and assess its benefits, requirements, and limitations. We conclude
that a proof-of-principle demonstration based on a micro-optomechanical system
is demanding, but possible. However, for parameters relevant to gravitational
wave detectors the requirements for backaction evasion appear to be
prohibitive.
