| 1. |
- Ergül, Adem, et al.
(författare)
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Spatial and temporal distribution of phase slips in Josephson junction chains
- 2017
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- The Josephson effect, tunnelling of a supercurrent through a thin insulator layer between two superconducting islands, is a phenomena characterized by a spatially distributed phase of the superconducting condensate. In recent years, there has been a growing focus on Josephson junction devices particularly for the applications of quantum metrology and superconducting qubits. In this study, we report the development of Josephson junction circuit formed by serially connecting many Superconducting Quantum Interference Devices, SQUIDs. We present experimental measurements as well as numerical simulations of a phase-slip center, a SQUID with weaker junctions, embedded in a Josephson junction chain. The DC transport properties of the chain are the result of phase slips which we simulate using a classical model that includes linear external damping, terminating impedance, as well as internal nonlinear quasiparticle damping. We find good agreement between the simulated and the experimental current voltage characteristics. The simulations allow us to examine the spatial and temporal distribution of phase-slip events occurring across the chains and also the existence of travelling voltage pulses which reflect at the chain edges.
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| 2. |
- Krupko, Yu., et al.
(författare)
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Kerr nonlinearity in a superconducting Josephson metamaterial
- 2018
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 98:9
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Tidskriftsartikel (refereegranskat)abstract
- We present a detailed experimental and theoretical analysis of the dispersion and nonlinear Kerr frequency shifts of plasma modes in a one-dimensional Josephson junction chain containing 500 superconducting quantum interfence devices in the regime of weak nonlinearity. The measured low-power dispersion curve agrees perfectly with the theoretical model if we take into account the Kerr renormalization of the bare frequencies and the long-range nature of the island charge screening by a remote ground plane. We measured the self- and cross-Kerr shifts for the frequencies of the eight lowest modes in the chain. We compare the measured Kerr coefficients with theory and find good agreement.
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| 3. |
- Weissl, Thomas, et al.
(författare)
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A general characterization method for nonlinearities in superconducting circuits
- 2019
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Ingår i: New Journal of Physics. - : IOP PUBLISHING LTD. - 1367-2630. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- Detailed knowledge of nonlinearity in superconducting microwave circuits is required for the optimal control of their quantum state. We present a general method to precisely characterize this nonlinearity to very high order. Our method is based on intermodulation spectroscopy at microwave frequencies and does not require DC-connection or DC-measurement of an on-chip reference structure. We give a theoretical derivation of the method and we validate it by reconstructing a known nonlinearity from simulated data. We experimentally demonstrate the reconstruction of the unknown nonlinear current-phase relation of a microwave resonator with superconducting nanowires.
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| 4. |
- Weissl, Thomas, et al.
(författare)
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Quantum correlations in microwave frequency combs
- 2017
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Ingår i: Optics InfoBase Conference Papers. - : Optical Society of America. - 9781557528209
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Konferensbidrag (refereegranskat)abstract
- We present an experimental study of quantum correlations in microwave frequency combs. We create and analyze the comb using a multi-frequency lock-in technique. Correlations between frequencies are created when driving a non-linear superconducting resonator.
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