Optimal Gaussian measurement for general Gaussian-state discrimination

Characterize the optimal Gaussian measurement for discriminating general Gaussian quantum states.

Background

The paper focuses on discriminating two two-mode squeezed vacuum states using local homodyne measurements. Although homodyne detection is shown to be suitable for the paper’s success-probability–fidelity score, the optimal Gaussian measurement is not known for discrimination of general Gaussian states. Resolving this question would extend the framework beyond the specific pair of states studied here.

References

Although not all non-Gaussian operations are currently practical, some are performed routinely, such as photon counting, and others, like the cubic phase gate and selective number arbitrary phase (SNAP) gate, have seen significant progress in recent years . They are still of theoretical relevance for understanding and realising the fundamental limits of such tasks.

— Local Gaussian bounds on the non-destructive discrimination of two-mode squeezed states  (2609.01373 - So et al., 1 Sep 2026) in Section Conclusion