I do theoretical research on how to preserve and strengthen quantum memories, which is essential for carrying out quantum-information processing and for developing a successful quantum computer. Quantum memories can be encoded in a single particle, such as an atom or photon, but most of my work explores how to store and protect them in many-body, or multi-particle, systems. The models I’m currently looking at correspond to having an array of many quantum bits, or “qubits,” which is what you need to build a quantum network capable of performing complicated computations. What interests me most right now, both fundamentally and from a quantum-computing standpoint, is this question of whether we can protect a such quantum system from decoherence—that is, from collapsing into a non-quantum state. How can we do this in a physically reasonable way?  You can achieve it in four dimensions—but you can’t build a four-dimensional system, so what are our options, realistically?