A new approach to single-qubit operations using exchange interactions of single electrons in gate-defined quantum dots has recently been demonstrated: the resonant exchange qubit. We show that two-qubit operations, specifically the CPHASE gate, can be performed between resonant exchange qubits very straightforwardly, using a single exchange pulse. This is in marked contrast to the best known protocols for exchange qubits where such a gate requires many pulses so that leakage processes arising from the exchange interaction can be overcome. For resonant exchange qubits a simple two-qubit gate is possible because in this mode of operation energy conservation suppresses leakage.

4+4 pages, 2 figures, supplementary information included, comments welcome, v.2 updated with arxiv numbers for references to arxiv:1304.3407 and arxiv:1304.3413