<i>In situ</i>
 tunable nonlinearity and competing signal paths in coupled superconducting resonators

Fischer, Michael; Chen, Qi-Ming; Besson, Christian; Eder, Peter; Goetz, Jan; Pogorzalek, Stefan; Renger, Michael; Xie, Edwar; Hartmann, Michael J.; Fedorov, Kirill G.; Marx, Achim; Deppe, Frank; Gross, Rudolf

doi:10.1103/physrevb.103.094515

Cited by 6 publications

(2 citation statements)

References 37 publications

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“…The system studied in our experiment is realized by embedding a weakly asymmetric superconducting quantum interference device (SQUID) in the middle of a coplanar waveguide resonator. By driving it with a coherent microwave field, we implement a Duffing oscillator in superconducting quantum circuits with tunable frequency and Kerr nonlinearity 23 , 24 , as shown in Fig. 1 a.…”

Section: Resultsmentioning

confidence: 99%

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Quantum behavior of the Duffing oscillator at the dissipative phase transition

et al. 2023

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The non-deterministic behavior of the Duffing oscillator is classically attributed to the coexistence of two steady states in a double-well potential. However, this interpretation fails in the quantum-mechanical perspective which predicts a single unique steady state. Here, we measure the non-equilibrium dynamics of a superconducting Duffing oscillator and experimentally reconcile the classical and quantum descriptions as indicated by the Liouvillian spectral theory. We demonstrate that the two classically regarded steady states are in fact quantum metastable states. They have a remarkably long lifetime but must eventually relax into the single unique steady state allowed by quantum mechanics. By engineering their lifetime, we observe a first-order dissipative phase transition and reveal the two distinct phases by quantum state tomography. Our results reveal a smooth quantum state evolution behind a sudden dissipative phase transition and form an essential step towards understanding the intriguing phenomena in driven-dissipative systems.

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Section: Resultsmentioning

confidence: 99%

“…The in-situ tunable Duffing oscillator consists of a 7.2 mm long necklace-type resonator with an asymmetric DC-SQUID embedded in the middle 23 , 24 , 36 (See Supplementary Fig. 1) .…”

Section: Methodsmentioning

confidence: 99%