Recent experiments on the organic compound $kappa-(BEDT-TTF)_2 Cu_2 (CN)_3$ raise the possibility that the system may be described as a quantum spin liquid. Here we propose a pairing state caused by the `Amperean attractive interaction between spinons on a Fermi surface mediated by the U(1) gauge field. We show that this state can explain many of the observed low temperature phenomena and discuss testable consequences.
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