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Measurement of geometric dephasing using a superconducting qubit
S Berger1, M Pechal1, P Kurpiers1
1Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland.
Nature Communications
|October 31, 2015
Summary
Quantum dephasing, which destroys quantum information, has dynamic and geometric origins. Geometric dephasing can restore or reduce qubit coherence based on its path in Hilbert space, even without acquiring a geometric phase.
Area of Science:
- Quantum Information Science
- Quantum Computing
- Superconducting Qubits
Background:
- Quantum systems lose information due to environmental interactions, a process called dephasing.
- Understanding dephasing is crucial for developing robust quantum technologies.
Purpose of the Study:
- To experimentally investigate the origins of dephasing in a quantum system.
- To differentiate between dynamic and geometric contributions to dephasing.
- To explore the role of geometric dephasing in coherence dynamics.
Main Methods:
- Utilized a superconducting qubit as the quantum system.
- Experimentally controlled the qubit's evolution path in its projective Hilbert space.
- Analyzed dephasing effects under varying conditions, including the adiabatic limit.
Main Results:
- Demonstrated that dephasing has both dynamic and geometric origins.
- Showed that geometric dephasing occurs even in the adiabatic limit and without geometric phase acquisition.
- Found that geometric dephasing's effect on coherence (reduction or restoration) depends on the orientation of the qubit's Hilbert space path.
- Confirmed geometric dephasing accompanies any noisy system evolution in Hilbert space.
Conclusions:
- Dephasing is a multifaceted phenomenon with distinct dynamic and geometric components.
- Geometric dephasing is an intrinsic feature of quantum evolution under noise and can be manipulated.
- Controlling geometric dephasing offers potential pathways to enhance quantum coherence and information preservation.
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