Probing Low-Frequency Charge Noise in Few-Electron CMOS Quantum Dots
Résumé
Charge noise is one of the main sources of environmental decoherence for spin qubits in silicon, presenting a major obstacle in the path towards highly scalable and reproducible qubit fabrication. Here we demonstrate in-depth characterization of the charge noise environment experienced by a quantum dot in a CMOS-fabricated silicon nanowire. We probe the charge noise for different quantum dot configurations, finding that it is possible to tune the charge noise over two orders of magnitude, ranging from 1μeV2/Hz to 100μeV2/Hz. In particular, we show that the top interface and the reservoirs are the main sources of charge noise, and their effect can be mitigated by controlling the quantum dot extension. Additionally, we demonstrate a method for the measurement of the charge noise experienced by a quantum dot in the few-electron regime. We measure a comparatively high charge noise value of 40μeV2/Hz at the first electron, and demonstrate that the charge noise is highly dependent on the electron occupancy of the quantum dot.
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