Probing Low-Frequency Charge Noise in Few-Hole Physically-Defined Ge Quantum-Dot Single-Hole Transistors

Charge noise is a primary source causing decoherence of quantum states in semiconductor quantum-dot (QD) qubits, limiting their scalability and fidelity toward practical quantum computing. In this study, we reported low-frequency charge noise behavior of Ge QD single-hole transistors operating in the few-hole regime, in particular, when an additional charge is resonantly passing through the QD (current peak) or Coulomb-blocked (current valley) in the shell-filling and tunneling processes. Estimated charge noise level of our Ge QD at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{f}=\boldsymbol{1}$</tex> Hz, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{T}=\boldsymbol{4.5}\ \mathbf{K}$</tex> is~ 80 μeV<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>/Hz.