arXiv subjects

Ze-Yan Chen

Publications and source records attributed to Ze-Yan Chen.

2 recordsLinked to original sources

arXiv2026

Coulomb Blockade in a One-Dimensional Array of Strong Josephson Junctions

We measure current across a voltage-biased, long array of Josephson junctions. Current-voltage characteristics do not reveal any critical current and instead display the presence of threshold voltage and finite activation energy, consistent with the Coulomb blockade. However, the respective energy scale is well below the value prescribed by a single-island geometric capacitances. We explain it by strong quantum fluctuations of charge associated with a large value of Josephson energy, $E_J\gg E_C$, where $E_C$ is the charging energy associated with the inter-island capacitance. Comparison between the data and theory points to an exponential (in parameter $E_J/E_C$) suppression of the threshold. We achieve a quantitative agreement with theory by accounting for charge-$e$ solitons associated with the quasiparticles entering the array from its leads. This scenario however underestimates the current below threshold in comparison with the experiment.

cond-mat.mes-hall↗

arXiv2026

Revisiting dissipation-driven phase transition in a Josephson junction

Despite extensive experimental and theoretical work over several decades, Schmid-Bulgadaev quantum phase transition remains a subject of debate. Here we revisit this problem by performing systematic experiments on low-frequency current-voltage characteristics of Josephson junctions over a wide range of parameters. The experiments are conducted in a true resistive environment formed by a metallic on-chip resistor located near the junction. Over the parameter range of the experiment, we find that the transition occurs when the resistance crosses the quantum value $h/(4e^2)\simeq 6.5$ k$Ω$ for Cooper pairs, as originally predicted. The temperature $T$ of the experiment is naturally non-zero, but our basic theoretical modeling corroborates that the observations under these conditions can serve as the basis for the conclusions made, in particular, the crossover resistance from superconducting to insulating regime is the same as that at $T=0$.

cond-mat.supr-con↗