“…In the one dimensional case, this problem has been addressed by Ingham [10], Levinson [14], Paley and Wiener [15,16] and their results are in terms of non integrability of ψ(t) t −2 over [1, ∞). Recently this problem has received considerable attention and several versions have been proved in the contexts of R n , nilpotent Lie groups and compact and non-compact Riemannian symmetric spaces, see the works [2], [3], [4], [5] of Bhowmik, Pusti, Ray and Sen in various combinations of authorship. Recently, in a joint work with Bagchi and Sarkar [1] we have proved an analogue of Ingham's theorem for the operator valued Fourier transform on the Heisenberg group.…”