  Quantum mechanics sets a limit for the precision of continuous measurement of
the position of an oscillator. Here we show how it is possible to measure an
oscillator without quantum backaction of the measurement by constructing one
effective oscillator from two physical oscillators. We realize such a
quantum-mechanics free subsystem using two micromechanical oscillators, and
show the measurements of two collective quadratures while evading the quantum
backaction by $8$ decibels on both of them, obtaining a total noise within a
factor two of the full quantum limit. This facilitates detection of weak forces
and the generation and measurement of nonclassical motional states of the
oscillators. Moreover, we directly verify the quantum entanglement of the two
oscillators by measuring the Duan quantity $1.4$ decibels below the
separability bound.
