From Adiabatic to Dispersive Readout of Quantum Circuits

Area of Science:

• Quantum computing
• Quantum information science
• Circuit quantum electrodynamics

Background:

• Quantum circuit properties are typically measured using microwave resonators.
• Existing theories describe resonator frequency shifts under specific detuning conditions (strong vs. small).
• A unified theoretical framework is needed to accurately describe quantum circuit readout across different detuning regimes.

Purpose of the Study:

• To develop a comprehensive theory for quantum circuit readout.
• To bridge the gap between existing theoretical models for strongly and weakly detuned systems.
• To demonstrate the necessity of this unified theory for general quantum circuit characterization.

Main Methods:

• Developing a theoretical model that unifies distinct limits of resonator-circuit detuning.
• Analyzing the spectral properties of quantum circuits coupled to microwave resonators.
• Illustrating the theory's application with specific examples of quantum circuit readout.

Main Results:

• The presented theory successfully bridges the limits of strong and small detuning in quantum circuit readout.
• The model provides a more general description applicable across various detuning regimes.
• Examples demonstrate the theory's necessity for accurate readout.

Conclusions:

• A unified theory is essential for a complete understanding of quantum circuit readout via microwave resonators.
• The developed framework enhances the accuracy and applicability of readout techniques.
• This work advances the characterization and control of quantum circuits.