To determine the density matrix it is necessary to measure the expectation values of a set of operators which form a complete basis of the Hilbert space, which for magnetic resonance experiments is most conveniently represented in the Cartesian basis. Only single quantum coherences can be directly detected in magnetic resonance echo experiments, and so the remaining operators must be converted to a detectable form in order to measure their expectation values. A general protocol for performing quantum state tomography on an 𝑛qubit system by NMR consists of a series of experiments in which one of three operations is applied to each spin prior to detection of the FID signal. The choices of operations are: i. do nothing, or apply a 90° 'filter' pulse along ii. +𝑥 or iii. +𝑦, which we will denote 1, X, and Y, respectively. In a two-qubit system there are nine possible pairs of operations, and any Cartesian operator can be converted into a detectable single-quantum in-or anti-phase coherence by at least one combination (Table ). While it is possible to measure all operators with just four combinations it is common practice to perform all nine experiments to allow for repeated observations. This protocol relies on the ability to measure both in-and anti-phase coherences. However the ensemble broadening of EPR spectra precludes the direct detection of anti-phase coherences in the weak inter-spin coupling regime that we consider here. As a result, to transfer this procedure from NMR to EPR it is necessary to devise a detection sequence capable of measuring the expectation values of anti-phase coherences. To accomplish this, we draw inspiration from the 3P-and 4P-Double Electron-Electron Resonance (DEER) experiments (Figure ) in which the application of a pump pulse at time 𝑡 prevents refocussing of precession under the inter-spin coupling Hamiltonian