A Flexible Control System for Quantum Dot Qubits*

The advancement of Quantum Dot qubit technology is paving the way to fault-tolerant quantum computing systems. Although spin qubits are still at a relatively early stage, their strong robustness against noise makes them extremely attractive. However, quantum architectures still rely on classical electronics for control and readout. While traditional instrumentation has been used to manipulate and detect qubit spins, they lack the scalability necessary to move from single qubit to multi-qubit experiments. Even if the instruments can be synchronized for signal phase coherence, they lack the flexibility that is required for researchers to explore new control techniques and qubit architectures. This flexibility can be achieved through Digital Signal Processing (DSP) realized on Field Programmable Gate Arrays (FPGA). FPGAs allow the implementation of a range of DSP algorithms while also providing absolute time determinism. This paper discusses the use of commercial FPGA based instruments to implement a spin-qubit control system. A lock-in amplifier is implemented in the FPGA of the digitizer and quantum dot Coulomb blockade measurements are compared to when using a dedicated lock-in amplifier.