Charge control in a 2x2 semiconductor quantum-dot array with shared control electrodes.

Quantum computing offers a way to solve physics and computing problems that cannot be solved in reasonable times by classical computers. However, quantum computers are prone to errors, which require encoding the information of a single logical quantum-bit (qubit) into many physical qubits. Consequently, a universal quantum computer outperforming current supercomputers involves controlling millions of qubits. In this context, spin qubit in quantum-dot (QD) arrays are a good candidate thanks to their compatibility with standard semiconductor manufacturing.

In this presentation, we demonstrate a scalable QD array formed of shared control gates with row/column addressing, in a GaAs/AlGaAs heterostructure. Similar to classical integrated circuits, large-scale quantum-dot arrays must drastically reduce the number of interconnects. Here, the crossbar network limits the number of electrodes for a ??x?? QD array to only 4??. We show the loading and trapping of one to five electrons inside a single-dot. Then, despite the limited number of electrodes, we control the electron distribution in the isolated 2x2 QD array for the different numbers of loaded charges. The constant interaction model reproduces the isolated stability diagrams and characterizes the QD array. In addition, we show the ability to tune the inter-dot tunnelling rate from the GHz to the sub-kHz regime.