For Spin qubit Larmor resonance ‘addressing’, frequencies in the range of 10-20 GHz are required. Precise frequency and pulse-amplitude control is realized using high performance digital controlled IQ AWG signal generators. These IQ signals, nowadays in the range up to ~500 MHz needs to be upconverted ‘undistorted/transparently’ to the required Spin resonance µWave frequencies. A relatively expensive instrument like a Vector Signal Generator (VSG, e.g. from KeySight or R&S) is used for that at the moment, to obtain a single µWave output signal. For multiple qubit resonances to be controlled, multi-tones and/or multi-channel upconverters are required. For that, a custom designed upconverter approach has been applied in which multi-channel outputs with either single- or multi-tone µWave signals are made available over a wide but dedicated frequency range. It uses two ‘generic’ PCB designs all populated with COTS RF/µWave components, where only two/three parts determine the frequency ranges covered for each channel output signal. Each single-tone output channel covers a 1 GHz range which can be set anywhere in a 4 GHz band somewhere between 10-20 GHz, defined by only two/three variable components/parts placement. Precise frequency control is done similar as for controlling a VSG. The IQ AWG input signal, which can be a single- or multi-tone frequency pulsed signal, is ‘transparently’ upconverted to the required µWave frequency. For the upconverter steps, special care has been taken in the design for appropriate spurious/harmonic suppression and signal ‘quality’ like frequency stability, phase-noise and other distortions.
Reindert Grooters, TNO
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