World’s best in industry TWPA: QuantWare Crescendo-S Long-term Performance Stability

As the quantum computing field focuses on scaling up and optimizing hardware components, the challenge of maintaining reliable, high-fidelity qubit readout at scale becomes crucial. At QuantWare, we are committed to solving this challenge by developing essential hardware like the Crescendo-S Travelling Wave Parametric Amplifier (TWPA), a key element in enabling high-fidelity readout at scale.

Crescendo-S is the world’s best-in-industry TWPA, trusted by universities, research institutions, and enterprises globally. Built for the most demanding quantum systems, it brings exceptional stability and reliability to the most complex quantum experiments.

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Benchmark Performance: Near Quantum-Limited Amplification

The Crescendo-S provides near quantum-limited gain across a broad frequency range, ensuring high signal-to-noise ratio (SNR) to boost readout performance.

Key Device Characteristics

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Critical Stability Metrics for Complex Systems

The transition from small, academic systems to high-qubit count, quantum error corrected, industry-scale quantum computers demands not just peak performance, but exceptional stability and reliability of every component. Crescendo-S excels at both metrics.

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1. Operational Stability

For long-duration experiments, the output of pump sources used to control TWPAs can drift due to variations in laboratory temperature and humidity, typically following a diurnal cycle. Together with other effects, this may cause the amplifier behaviour to change over time, leading to a loss of optimal calibration and degraded readout performance.

Characterising stability of performance of TWPAs is therefore critical to qualifying suitability to industry-scale quantum computing systems. Crescendo-S demonstrates superior operational stability:

‍Methodology: Amplifier behaviour was measured over a full 24 hour diurnal cycle, with performance measurements recorded every 10 minutes.
‍Quantified Stability:
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• Gain fluctuation over time (σ): Only 0.05 dB.
• Maximum Gain Delta: The maximum fluctuation in gain over the full 24 hours was contained to just 0.25 dB.

This metric confirms that Crescendo-S maintains the required stable performance, minimizing the need for recalibration.

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2. Inter-Cooldown Stability: Stability and Reliability Across Thermal Cycles

In low-throughput industry-grade quantum systems, cooldowns are rare and costly. Each cycle from room to base temperature carries the risk of component failure and system downtime. Ensuring that every TWPA withstands multiple thermal cycles is therefore critical for maintaining uptime and reducing operational delays. ‍

Methodology: The data shows the Gain and SNR Improvement (SNRi) of an identical device across multiple thermal cycles over several months (February to July 2025). Gain and SNRi are independently optimized after each thermal cycle.
Quantified Reproducibility:

• Gain fluctuation (σ): 0.4 dB (2%) between cooldowns.
• SNRi fluctuation (σ): 0.6 dB (6%) between cooldowns.

The consistency observed across multiple devices and cooldowns validates the reproducibility of Crescendo-S state-of-the-art performance, reinforcing QuantWare’s position as a scalable and reliable source of industrial-grade TWPAs.

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Integration and the Quantum Open Architecture

The Crescendo-S TWPA is a testament to QuantWare's commitment to the Quantum Open Architecture model. It integrates seamlessly into any quantum computing stack, providing a scalable alternative to proprietary readout solutions and empowering users to build scalable quantum systems with globally sourced, high-performance parts.

For ease of use, Crescendo-S is compatible with Zurich Instruments’ SHFPPC Parametric Pump Controller, a solution that simplifies the tuning of multiple parametric amplifiers, allowing researchers to focus on their experimental results.

The proven performance, stability, and robustness of Crescendo-S, demonstrated by data and trusted by leading institutions like the University of Waterloo and the Electronics and Telecommunications Research Institute (ETRI) offer the foundational readout capabilities necessary for the next leap in quantum computing scale.

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