MIT and University of Ferrara researchers created a mathematical blueprint for designing distinguishable non-Gaussian quantum states. Researchers worldwide are working to develop quantum systems for sensing, communications, computing, and control that could outperform today’s technologies. A major challenge is creating quantum states that are stable, measurable, and easy to distinguish, since these states are the foundation of any practical quantum device. Quantum states have unique characteristics that make them attractive for advanced information processing. However, achieving both stability and distinguishability remains difficult. Recovering information from a quantum system depends on how well its quantum states can be distinguished, a property tied to orthogonality. Because no two Gaussian states (a widely studied class of quantum states) are orthogonal, some level of error is unavoidable when trying to tell them apart. Current quantum devices also remain stable for only fractions of a second and often rely on complicated methods to distinguish between quantum states. Researchers at MIT and the University of Ferrara have now developed a new technique for creating more easily distinguishable states, a step that could support the next generation of quantum technologies. The approach is detailed in a paper published in Physical Review A by Moe Z. Win and Peter L. Falb of MIT, together with Andrea Giani and Andrea Conti of the University of Ferrara. The researchers discovered a way to translate quantum states of light into algebraic varieties (a mathematical structure from abstract algebra), allowing the problem to be expressed as mathematical equations that can be solved more easily. Designing More Distinguishable Quantum States “Quantum systems can provide performance that is significantly better than classical counterparts,” Win says, “but this doesn’t come for free.” To build practical devices that generate and detect different quantum states, “one needs to carefully engineer the quantum states in which they encode