Related Experiment Video
Updated: May 15, 2026
06:42
Generation and Coherent Control of Pulsed Quantum Frequency Combs
Published on: June 8, 2018
Quantum back-action of an individual variable-strength measurement
M Hatridge1, S Shankar, M Mirrahimi
1Department of Applied Physics and Physics, Yale University, New Haven, CT 06520, USA. michael.hatridge@yale.edu
Science (New York, N.Y.)
|January 12, 2013
Summary
Researchers precisely tracked a superconducting qubit
Area of Science:
- Quantum physics
- Quantum information science
- Superconducting circuits
Background:
- Quantum measurements can disturb quantum systems.
- The impact of measurement back-action depends on the measured property.
- Ideal partial measurements should preserve the system's purity.
Purpose of the Study:
- To experimentally verify the predicted behavior of quantum systems under ideal partial measurement.
- To demonstrate accurate quantum state monitoring for feedback control.
Main Methods:
- Utilized a superconducting qubit dispersively coupled to a microwave cavity.
- Performed a single measurement of both signal quadratures.
- Observed and characterized the measurement back-action on the qubit state.
Main Results:
- Demonstrated that the qubit remained in a pure state after partial measurement.
- Observed stochastic back-action on the qubit, dependent on the measurement outcome.
- Showcased the ability to track the qubit's evolution using the measurement record.
Conclusions:
- Experimental validation of quantum theory predictions for partial measurements.
- Accurate quantum state monitoring is achievable.
- Essential step towards measurement-based feedback control in quantum systems.
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