Quantum information theory

The group works at the foundations of quantum information theory, where the central question is how the rules of quantum mechanics constrain what can be learned, communicated, and kept secret. A particular focus is device-independent cryptography: protocols whose security follows from observed violations of Bell inequalities alone, requiring no trust in the internal workings of the devices that carry them out. Establishing such guarantees rigorously calls for tools that bound an adversary's knowledge directly from correlations between measurement outcomes.

Underpinning this effort is entanglement theory and quantum information measures — entropies, the structure of correlations, and how these quantities behave when many systems are composed or processed in sequence. The group develops mathematical techniques, such as entropy accumulation and reductions from general attacks to simpler structured ones, that turn statements about idealized single rounds into provable security for realistic, finite protocols. The aim is to put quantum cryptography on the same firm logical footing that classical complexity-based cryptography has long enjoyed, while clarifying which physical resources genuinely enable advantage.