Probing the parity of Quantum dot-hybrid systems with gate reflectometry

Quantum dot coupled to superconductors has been proved to be a reliable platform to realize Kitaev chain [1,2] and a promising way to realize parity qubits with Majorana modes [3]. Quasiparticle poisoning in quantum dot-superconductor systems is a fundamental challenge for the life time in such hybrid systems. Gate reflectometry allows fast, noninvasive detection of quantum capacitance [4] associated with quasiparticle poisoning events flipping the parity. Here we study two quantum dots coupled by a semiconductor-superconductor hybrid region in a two-dimensional electron gas, using reflectometry to probe the parity of the system. We observe quasiparticle poisoning events flipping the parity from both quantum dot plunger gates and from the superconductor. The technique is useful for further study on similar systems such as Kitaev chain and qubits made with Kitaev chain.

 

[1] Dvir, T., Wang, G., van Loo, N. et al. Realization of a minimal Kitaev chain in coupled quantum dots. Nature 614, 445–450 (2023).

[2] ten Haaf, S.L.D., Wang, Q., Bozkurt, A.M. et al. A two-site Kitaev chain in a two-dimensional electron gas. Nature 630, 329–334 (2024).

[3] Leijnse M, Flensberg K. Parity qubits and poor man's Majorana bound states in double quantum dots[J]. Physical Review B—Condensed Matter and Materials Physics, 2012, 86(13): 134528.

[4] Vigneau F, Fedele F, Chatterjee A, et al. Probing quantum devices with radio-frequency reflectometry[J]. Applied Physics Reviews, 2023, 10(2).