Quantum charge fluctuations of a proximitized nanowire

Understand

Motivated by recent experiment, we consider charging of a nanowire which is proximitized by a superconductor and connected to a normal-state lead by a single-channel junction.

• The charge $Q$ of the nanowire is controlled by gate voltage $e{\cal N}_g/C$.
• A finite conductance of the contact allows for quantum charge fluctuations, making the function $Q(\mathcal{N}_g)$ continuous.
• It depends on the relation between the superconducting gap $\Delta$ and the effective charging energy $E^*_C$.