Coherent and compact van der Waals transmon qubits

Demonstrates coherent, fully crystalline NbSe${}_2$/WSe${}_2$/NbSe${}_2$ merged-element transmons without external shunt capacitors. The first-generation devices reached microsecond-scale lifetimes; the best-performing device had mean $T_1=1.67\pm 0.27$ μs and best observed $T_1=2.46$ μs. Comparison with structurally similar capacitors identified dielectric loss as the dominant relaxation channel.

Key Results

• Coherent time-domain control in fully van der Waals mergemons
• Best mean $T_1=1.67\pm 0.27$ μs; best observed $T_1=2.46$ μs
• Junction participation of 96% for the best-performing device
• Dielectric loss remained dominant despite crystalline materials

Links

• arXiv: 2512.08059

Zoo Links

• mergemon
• transmon