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Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators
Published on: May 30, 2014
Phase-locking transition in a chirped superconducting Josephson resonator
O Naaman1, J Aumentado, L Friedland
1Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley, California 94720, USA.
Physical Review Letters
|October 15, 2008
Summary
Researchers observed a critical threshold for dynamic phase locking in a Josephson junction resonator driven by a chirped microwave signal. This finding enables precise measurement of the junction critical current, useful for quantum state detection.
Area of Science:
- Quantum optics
- Superconducting circuits
- Nonlinear dynamics
Background:
- High-Q transmission line resonators are fundamental components in quantum technologies.
- Josephson tunnel junctions exhibit unique quantum mechanical properties crucial for superconducting devices.
- Dynamic phase locking describes the synchronization of an oscillator to a time-varying driving signal.
Purpose of the Study:
- To investigate the dynamic phase locking behavior of a high-Q transmission line resonator coupled to a Josephson junction.
- To identify the critical drive amplitude threshold for phase locking.
- To explore the potential of this phenomenon for sensitive detection of Josephson junction parameters.
Main Methods:
- Driving a high-Q transmission line resonator with an embedded Josephson junction using a purely AC, chirped microwave signal.
- Varying the drive amplitude and chirp rate to observe phase locking transitions.
- Analyzing the resonator's amplitude and phase evolution near the phase locking threshold.
Main Results:
- A sharp threshold for dynamic phase locking was observed.
- The critical amplitude for phase locking is dependent on the chirp rate and sensitive to the junction critical current (I0).
- Below threshold, excitation occurs near the linear resonance frequency; above threshold, the resonator phase locks and amplitude grows to a deterministic maximum.
Conclusions:
- The observed phase locking behavior provides a sensitive, non-switching method for discriminating small changes in Josephson junction critical current.
- This phenomenon has potential applications in quantum state measurement and high-precision sensing.
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