Square-Wave Defined Pulse Generator for High Fidelity Gate Operation of Superconducting Qubits

Superconducting qubits are the promising candidate to realize large-scale quantum computing systems. Well-known quantum algorithms, such as Shor's algorithm, require at least <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$10^{5}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$10^{6}$</tex> qubits to execute. Accordingly, classical systems for controlling superconducting qubits must also be scalable. One critical scalability challenge lies in the circuit cost of an RF pulse generator used to implement quantum gate operations. This poster proposes a cost-effective architecture for an RF pulse generator tailored to superconducting qubits. Most existing works use arbitrary waveform generators (AWGs) that require both a high-bandwidth memory (HBM) and a high-performance digital-analog converter (DAC) to achieve the highest gate fidelity with an optimized RF pulse waveform. The proposed pulse generator architecture significantly simplifies both the generator circuit and the waveform of the RF pulse to cost-aware square pulses. This architecture eliminates the requirement for power- and cost-intensive AWG, which is a major obstacle in realizing scalable quantum computers. Additionally, this poster demonstrates that our architecture can mitigate the error source associated with simplified RF pulses. Quantum dynamics simulation of transmon qubits, wherein the state of the system evolves with time, demonstrates that our pulse generator can achieve practically the same fidelity of gate operations for single and multiple qubits as ideal RF pulses while substantially reducing the sampling rate of DACs and the bandwidth of memories.