  The backaction of quantum measurement on the Kondo effect in a quantum dot
system is investigated by considering continuous projective measurement of
singly occupied states of a quantum dot. We elucidate the qualitative feature
of the Kondo effect under quantum measurement and determine effective Kondo
temperature affected by the measurement. The Kondo resonance in the spectral
function is suppressed when the measurement strength reaches the energy scale
of the Kondo temperature without measurement. Through the spin susceptibility,
we identify the generalized Kondo temperature under continuous quantum
measurement. The measurement backaction changes the singularity in the spin
susceptibility into a highly non-monotonic temperature dependence around the
generalized Kondo temperature. The dependence of the generalized Kondo
temperature on the measurement strength is quantitatively discussed.
