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Relaxation and the Zeno effect in qubit measurements
S A Gurvitz1, L Fedichkin, D Mozyrsky
1Department of Particle Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
Physical Review Letters
|August 26, 2003
Summary
We derived Bloch-type equations for a monitored qubit system. Our findings show that environmental interactions prevent qubit localization, even with infinite decoherence.
Area of Science:
- Quantum physics
- Quantum information science
Background:
- Understanding qubit dynamics is crucial for quantum computing.
- Continuous monitoring of quantum systems presents unique challenges.
Purpose of the Study:
- To derive and analyze Bloch-type equations for a qubit interacting with its environment and a detector.
- To evaluate detector current and noise spectrum in terms of qubit decoherence and relaxation rates.
- To investigate the fundamental limits of qubit localization during measurement.
Main Methods:
- Derivation of Bloch-type equations for the coupled qubit-environment-detector system.
- Analysis of detector current and noise spectrum using the derived equations.
- Theoretical demonstration of qubit localization limits.
Main Results:
- Obtained simple expressions for detector current and noise spectrum.
- Quantified the relationship between measurement properties and qubit decoherence/relaxation rates.
- Demonstrated that environmental interactions inherently limit qubit localization.
Conclusions:
- The derived equations provide a framework for accurate measurement of qubit decoherence and relaxation.
- Qubit localization is fundamentally limited by environmental interactions, irrespective of decoherence rate.