Detection of the tensor perturbations predicted in inflationary models is important for testing inflation as well as for reconstructing the inflationary potential. We show that because of cosmic variance the tensor contribution to the square of the cosmic background radiation quadrupole anisotropy must be greater than about 14% of the scalar contribution to ensure a statistically significant detection of tensor perturbations. This sensitivity could be achieved by full-sky measurements on angular scales of 3° and 0.5°.

• Received 18 July 1994

DOI:https://doi.org/10.1103/PhysRevLett.73.3347