  A stochastic gravitational wave background is expected to emerge from the
superposition of numerous gravitational wave sources of both astrophysical and
cosmological origin. A number of cosmological models can have a parity
violation, resulting in the generation of circularly polarised gravitational
waves. We present a method to search for parity violation in the gravitational
wave data. We first apply this method to the most recent, third, LIGO-Virgo
observing run. We then investigate the constraining power of future A+
LIGO-Virgo detectors, including KAGRA to the network, for a gravitational wave
background generated by early universe cosmological turbulence.
