Which version are you using? This works for me:
>>> torch.cuda.FloatTensor(3).pow(2)

1.00000e-02 *
  0.0003
  0.1568
  1.0655
[torch.cuda.FloatTensor of size 3 (GPU 0)]

>>> torch.FloatTensor(3).pow(2)

 8.7180
 0.0000
 8.7180
[torch.FloatTensor of size 3]