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In Situ Characterization of Qubit Control Lines: A Qubit as a Vector Network Analyzer
Markus Jerger1, Anatoly Kulikov1,2, Zénon Vasselin1
1ARC Centre of Excellence for Engineered Quantum Systems, The University of Queensland, St Lucia, Queensland 4072, Australia.
Physical Review Letters
|November 9, 2019
Summary
We developed a new quantum technique using a qubit as a vector network analyzer to measure control line transfer functions. This method enhances the fidelity of entangling gates in quantum processors.
Area of Science:
- Quantum Computing
- Quantum Control Systems
- Superconducting Qubits
Background:
- Accurate characterization of control lines is crucial for high-fidelity quantum operations.
- Traditional vector network analyzers may not be suitable for all quantum system components.
Purpose of the Study:
- To propose and demonstrate a novel qubit-based method for measuring control line transfer functions.
- To enhance the fidelity of entangling gates in quantum processors.
Main Methods:
- Utilizing a qubit as a vector network analyzer.
- Coupling the control line to the qubit's longitudinal Hamiltonian component.
- Inducing Rabi oscillations via simultaneous transverse driving.
Main Results:
- Successfully measured the frequency-domain transfer function of a superconducting transmon qubit's flux control line (1-450 MHz).
- Improved the fidelity of a two-transmon qubit entangling cphase gate using the characterized control line data.
Conclusions:
- The qubit-based vector network analyzer technique is a viable method for characterizing quantum control lines.
- This technique offers a pathway to increased fidelity in quantum gate operations.
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