Weak measurements don’t defeat noise

In quantum physics, sometimes we may choose to perform measurements¬†weakly: we deliberately avoid learning too much about a system so that its wavefunction does not collapse. It’s been suggested that a series of such measurements, suitably amplified, may ultimately do better than a regular measurement when the apparatus suffers from noise. In a recent Phys. Rev. A article we determine this idea has, at best, very limited applicability.

This is work by George Knee, Simon Benjamin, GAD Briggs and Erik Gauger.