Controlled dephasing of an electron interferometer with a path detector at equilibrium.

Area of Science:

• Quantum physics
• Condensed matter physics
• Electron coherence

Background:

• Controlled dephasing typically requires coupling to external noise sources.
• Understanding electron behavior in quantum dots is crucial for quantum technologies.

Purpose of the Study:

• To investigate dephasing in a nearly isolated quantum dot.
• To explore the role of electron puddles in quantum interference.
• To demonstrate a novel dephasing mechanism independent of external noise.

Main Methods:

• Utilizing a nearly isolated electron puddle within a quantum dot.
• Operating at millikelvin temperatures and thermal equilibrium.
• Observing interference patterns in a nearby electronic interferometer.

Main Results:

• Complete dephasing of electron interference was observed.
• An abrupt and robust π phase slip accompanied the dephasing.
• The phenomenon's robustness was linked to the Friedel sum rule.

Conclusions:

• A quantum dot's electron puddle can induce dephasing without external noise.
• The Friedel sum rule governs the universality of this dephasing mechanism.
• This method provides access to isolated quantum dots inaccessible via conductance measurements.