Parametric Amplification for Silicon Quantum Devices

Leonardo Ranzani, Florent Lecocq, Gabe Peterson +4 more

Yanbei Chen

Ping Zhao, Zhichao Ye, Magnus Karlsson +1 more

We demonstrate continuous-wave phase-sensitive optical parametric amplification with 9.5 dB gain and a 1.2 dB noise figure, well below the conventional 3 dB quantum limit, using a single compact and dispersion-engineered integrated nonlinear Si3N4 waveguide.

N. Bergeal, Flavius Schackert, Michael Metcalfe +4 more

Simon Schaal, I. Ahmed, J. A. Haigh +12 more

Spins in silicon quantum devices are promising candidates for large-scale quantum computing. Gate-based sensing of spin qubits offers a compact and scalable readout with high fidelity, however, further improvements in sensitivity are required to meet the fidelity thresholds and measurement timescales needed for the implementation of fast feedback in error correction protocols. Here, we combine radio-frequency gate-based sensing at 622 MHz with a Josephson parametric amplifier, that operates in the 500-800 MHz band, to reduce the integration time required to read the state of a silicon double quantum dot formed in a nanowire transistor. Based on our achieved signal-to-noise ratio, we estimate that singlet-triplet single-shot readout with an average fidelity of 99.7% could be performed in 1 μs, well below the requirements for fault-tolerant readout and 30 times faster than without the Josephson parametric amplifier. Additionally, the Josephson parametric amplifier allows operation at a lower radio-frequency power while maintaining identical signal-to-noise ratio. We determine a noise temperature of 200 mK with a contribution from the Josephson parametric amplifier (25%), cryogenic amplifier (25%) and the resonator (50%), showing routes to further increase the readout speed.

Yichen Shen, Ping‐Yen Hsieh, Dhruv Srinivasan +5 more

We demonstrate bright two-mode squeezed states generated in silicon nitride microresonators using integrated seed-assisted optical parametric amplification (OPA). This integrated quantum source produces a bright squeezed quantum frequency comb spanning multiple mode pairs with frequency separations up to 11 THz, and achieves up to 5.6 dB of measured intensity-difference squeezing. We systematically explore how pump and seed detunings, gain and phase-matching conditions of nonlinear interaction influence squeezing performance. These factors extend beyond conventionally known squeezed-state-degradation with optical losses, impacting the achievable squeezing in integrated microresonators. These insights advance the fundamental understanding necessary for practical integrated quantum photonic devices, paving the way toward robust, scalable applications in quantum information processing and quantum-enhanced sensing.