Across the superconductor-to-insulator transition: temperature dependance of Coulomb blockade and microwave modes in a Josephson junction chain
ORAL
Abstract
Josephson junction (JJ) chains represent an exceptional platform for experimentally investigating many-body physics, owing to their straightforward fabrication and the ability to design and control their energy parameters. These systems have demonstrated low-loss, high-impedance superconducting behavior (acting as superinductors) in fluxonium-like qubits and resonators, alongside insulating characteristics in transport measurements.
With their applications in quantum computing and metrology, there has been a renewed interest in the superconductor-to-insulator transition (SIT), which is expected when the charge screening energies (Ec, Eg) surpass the Josephson energy (Ej). Transport measurements clearly show the blockade of current [1], while low-loss RF modes are observed in high-resistance arrays [2]. Theoretical predictions have also explored the scaling of these phenomena with temperature, length and frequency. However, the presence of Coulomb blockade in DC transport together with the postulated existence of low-loss RF modes has not been observed to date [3].
In this study, we present both RF and DC measurements in a galvanically coupled fully-insulating JJ chain, and probe the predicted SIT as a function of temperature [4]. Notably, we realize the insulating phase by decreasing Eg, i.e. positioning the device in close proximity of the ground plane. This configuration may offer insights into the physics of disorder (charge offsets) and quantum phase slips across the SIT.
[1] Cedergren K. et al. Insulating Josephson Junction Chains as Pinned Luttinger Liquids, Phys. Rev. Lett. 119, 167701 (2017).
[2] Kuzmin R. et al. Quantum electrodynamics of a superconductor–insulator phase transition. Nat. Phys. 15, 930–934 (2019).
[3] Bard M. et al. Superconductor-insulator transition in disordered Josephson-junction chains. Phys. Rev. B 96, 064514 (2017).
[4] Mukhopadhyay S. et al. Superconductivity from a melted insulator in Josephson junction arrays. Nat. Phys. 19, 1630–1635 (2023).
With their applications in quantum computing and metrology, there has been a renewed interest in the superconductor-to-insulator transition (SIT), which is expected when the charge screening energies (Ec, Eg) surpass the Josephson energy (Ej). Transport measurements clearly show the blockade of current [1], while low-loss RF modes are observed in high-resistance arrays [2]. Theoretical predictions have also explored the scaling of these phenomena with temperature, length and frequency. However, the presence of Coulomb blockade in DC transport together with the postulated existence of low-loss RF modes has not been observed to date [3].
In this study, we present both RF and DC measurements in a galvanically coupled fully-insulating JJ chain, and probe the predicted SIT as a function of temperature [4]. Notably, we realize the insulating phase by decreasing Eg, i.e. positioning the device in close proximity of the ground plane. This configuration may offer insights into the physics of disorder (charge offsets) and quantum phase slips across the SIT.
[1] Cedergren K. et al. Insulating Josephson Junction Chains as Pinned Luttinger Liquids, Phys. Rev. Lett. 119, 167701 (2017).
[2] Kuzmin R. et al. Quantum electrodynamics of a superconductor–insulator phase transition. Nat. Phys. 15, 930–934 (2019).
[3] Bard M. et al. Superconductor-insulator transition in disordered Josephson-junction chains. Phys. Rev. B 96, 064514 (2017).
[4] Mukhopadhyay S. et al. Superconductivity from a melted insulator in Josephson junction arrays. Nat. Phys. 19, 1630–1635 (2023).
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Presenters
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Andrea Trioni
Institute of Science and Technology Austria
Authors
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Andrea Trioni
Institute of Science and Technology Austria
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Andrew P Higginbotham
The James Franck Institute and Department of Physics, University of Chicago, University of Chicago
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Johannes M Fink
Institute of Science and Technology Austria