The 38-year-old actress recently unveiled a talent for music after performing the title track to Country Strong at the Country Music Awards, but said that there is no way that she will ever team up with Martin, who fronts British band Coldplay.
She told New! magazine, 'I think hell would freeze over first. So I guess if I did (form a band with Chris) it would be called the Hell Freezes Over Band.'
Explaining why they never attend red carpet events together, she added, 'He doesn't want people to listen to his music and automatically think of us as a couple.
'And I think it's better that way - it's nicer to keep it so that when we are at home it is our own thing.
'Then when we're in public that's our careers - it's just better to keep it separate.'