TITLE: ” From Majorana to Andreev and back “
SPEAKER: Ramón Aguado, Quantum Advanced Research Center (QuARC) & Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC
ABSTRACT: The promise of Majorana zero modes (MZMs) for fault-tolerant topological quantum computing stems from their unique non-Abelian statistics and inherent topological protection from local decoherence. However, after fifteen years of research, distinguishing MZMs from near-zero-energy Andreev bound states (ABSs) in hybrid devices remains a key challenge. This “Majorana versus Andreev” challenge has revealed that, rather than being a disadvantage, ABSs can serve as a foundation for novel superconducting qubit designs. One promising approach encodes a qubit in the spin of a quasiparticle residing in an ABS of a quantum dot. Embedding such a superconducting spin qubit into a transmon circuit provides an intrinsic spin-supercurrent coupling, enabling an effective interface with circuit quantum electrodynamics for coherent control and readout; as well as strategies for noise mitigation. Alternatively, a minimal Kitaev chain implemented in quantum dots coupled via superconductors is a promising platform for Majorana-based qubits. Even a minimal chain of two dots can host a pair of Majorana modes and store quantum information in their joint parity. Recent quantum capacitance measurements on such platforms have enabled single-shot parity readout and demonstrated parity lifetimes exceeding 1 millisecond. These results establish essential readout capabilities and resolve a long-standing experimental challenge, paving the way for time-domain control of Majorana-based qubits.
DATE: THURSDAY, June 18th, 2026
TIME: 11:40 am
LOCATION: Theoretical Physics Seminar Room
