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Is Wave Function Collapse Necessary? Explaining Quantum Nondemolition Measurement of a Spin Qubit within Linear
Harry E Dyte1, George Gillard1, Santanu Manna2
1Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom.
Physical Review Letters
|May 3, 2024
Summary
Researchers measured a quantum dot electron spin qubit using thousands of nuclear spins, achieving high-fidelity single-shot measurements. This method allows for quantum state observation without wave function collapse, aligning with Quantum Darwinism principles.
Area of Science:
- Quantum mechanics
- Quantum information science
- Solid-state physics
Background:
- The quantum measurement problem remains a fundamental challenge since quantum mechanics' inception.
- Developing robust methods for measuring quantum states is crucial for quantum technologies.
Purpose of the Study:
- To demonstrate a high-fidelity single-shot measurement technique for quantum dot electron spin qubits.
- To explore measurement backaction and its implications for quantum state observation.
- To investigate the compatibility of the measurement scheme with the Quantum Darwinism concept.
Main Methods:
- Utilized off-resonant coupling between a quantum dot electron spin qubit and a highly redundant ancilla composed of thousands of nuclear spins.
- Employed repeated measurements to achieve heralded qubit initialization and backaction-free detection of quantum jumps.
- Analyzed burstlike fluctuations in a thermally populated phonon bath contributing to measurement outcomes.
Main Results:
- Achieved high-fidelity single-shot qubit measurement with fidelity approximately 99.85%.
- Demonstrated heralded initialization and backaction-free detection of electron spin quantum jumps.
- Observed quantum jumps attributed to phonon bath dynamics.
Conclusions:
- The developed measurement technique provides a pathway for reliable quantum state readout.
- Measurement can link quantum states to classical observables without invoking "wave function collapse".
- Results support the Quantum Darwinism framework for understanding quantum measurement.
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