  We demonstrate a total charge parity measurement by detecting the radio
frequency signal that is reflected by a lumped element resonator coupled to a
single InAs nanowire double quantum dot. The high frequency response of the
circuit is used to probe the effects of the Pauli exclusion principle at
interdot charge transitions. Even parity charge transitions show a striking
magnetic field dependence that is due to a singlet-triplet transition, while
odd parity transitions are relatively insensitive to magnetic field. The
measured response agrees well with cavity input-output theory, allowing
accurate measurements of the interdot tunnel coupling and the resonator-charge
coupling rate g_c/2pi ~ 17 MHz.
