A fundamental challenge in quantum computing is to increase the number of operations within the qubit coherence time. While this can be achieved by decreasing the gate duration, the use of shorter signals increases their bandwidth and can cause leakage into energetically separated states. A common method to suppress leakage for short pulses is the Derivative Removal by Adiabatic Gate (DRAG) method, which, however, relies on IQ modulation of radio-frequency (RF) signals, thus cannot be applied to the baseband signals, e.g., for semiconductor spin qubits. This paper proposes a novel technique, Delayed Leakage Reduction (DLR), that suppresses leakage at targeted frequencies even for baseband control by using time-delayed repetitions of the control signal to enable rapid, high-fidelity operations. We apply DLR on the adiabatic CZ gate between two spin qubits and achieve fidelities exceeding 99.9% within 9.4 ns for a resonance frequency difference of only 100 MHz. Towards the experimental realization of the proposed control method, we also assess the impact on the fidelity of the sampling rate, noise, and signal quantization of the electronic hardware generating the control pulse, thus setting the minimum hardware requirements for any experimental demonstration. ... Read more

This paper presents a cryo-CMOS DAC for driving two-qubit gates in semiconductor spin qubits. Thanks to a current-integrating coarse/fine architecture implemented in a 16-nm FinFET process, the proposed design generates adiabatic waveforms for very fast (<50 ns) high-fidelity operations, while operating at sub- 1 K temperatures with a small footprint (0.026 mm2) and low power (275 μ W), thus demonstrating its compatibility with qubit co-integration. ... Read more