Mode Dependency of Quantum Decoherence Studied via an Aharonov-Bohm Interferometer

Area of Science:

• Quantum physics
• Condensed matter physics
• Nanoscale devices

Background:

• The Aharonov-Bohm (AB) effect is a quantum mechanical phenomenon.
• Decoherence is a key challenge in maintaining quantum states.
• Understanding decoherence in multi-mode systems is crucial for quantum technologies.

Purpose of the Study:

• To investigate the relationship between decoherence and the mode number (M) in a multiple-mode AB interferometer.
• To determine the decoherence rate by analyzing the variance of the AB oscillation amplitude.
• To identify the underlying mechanisms responsible for decoherence in this system.

Main Methods:

• Fabrication of a multiple-mode Aharonov-Bohm interferometer.
• Precise determination of the mode number (M) using the additivity rule of ballistic conductors.
• Measurement and analysis of the AB oscillation amplitude variance to deduce decoherence rate.
• Investigating the dependence of decoherence on M.

Main Results:

• The decoherence rate was found to be dependent on the mode number M.
• The AB oscillation amplitude decreased and fluctuated as M was reduced.
• A maximum normalized amplitude was observed at a specific mode number (M ≈ 9).
• Charge-fluctuation-induced dephasing was identified as a significant contributor to decoherence.

Conclusions:

• Decoherence in multi-mode AB interferometers is strongly influenced by the mode number.
• Charge fluctuations and system geometry play a critical role in the dephasing process.
• Optimizing phase coherence is achievable through deliberate device design, paving the way for engineering quantum coherence.