  We detail a quantum circuit capable of efficiently encoding analytical
approximations to gravitational wave signal waveforms of compact binary
coalescences into the amplitudes of quantum bits using both quantum arithmetic
operations and hybrid classical-quantum generative modelling. The gate cost of
the proposed method is considered and compared to a state preparation routine
for arbitrary amplitudes, where we demonstrate up to a four orders of magnitude
reduction in gate cost when considering the encoding of gravitational waveforms
representative of binary neutron star inspirals detectable to the Einstein
telescope. We demonstrate through a quantum simulation, that is limited to 28
qubits, the encoding of a second post-Newtonian inspiral waveform with a
fidelity compared to the desired state of 0.995 when using the Grover-Rudolph
algorithm, or 0.979 when using a trained quantum generative adversarial network
with a significant reduction of required gates.
