Introducing our travelling-wave parametric amplifier
Extremely low noise
We routinely measure our TWPA-added-noise to be below one photon. That is within our experimental margin of error of the standard quantum limit (0.5 photons).
Unmatched bandwidth and dynamic range
Bandwidth from 4.5 to 9.5 GHz (typical) and dynamic range of -95 dBm (typical).
Integrated flux line
Benefits of flux tuning without an external coil. Our patented on-chip flux line generates minimal stray magnetic fields, allowing dense packing of many TWPAs.
Integrated pump coupler
Our on-chip integrated superconducting pump coupler eliminates the need for external couplers and provides extremely low insertion loss, leading to higher performance and simpler wiring.
No aging effects
Optimal control parameters (pump and flux bias) remain constant indefinitely. Only one-time tune-up required.
Smallest form factor
With industry’s smallest form factor (25x18x15 mm), including pump coupler, there will be more room in your dilution refrigerator for other components.
Besides its near-quantum-limited noise performance, AI-TWPA-C offers exceptionally broad bandwidth (5GHz without any stop bands), high dynamic range, ease of use, and excellent stability from cooldown to cooldown. We also provide comprehensive instructions and support for installation and tune-up which, together with excellent stability, lead to a low total cost of ownership.
AI-TWPA-C is also the only commercially-available solution with an on-chip integrated superconducting pump coupler, leading to significant increase of quantum efficiency (see below).
The source of energy in a traveling-wave parametric amplifier comes from a strong microwave tone, called the pump, that copropagates with the signal being amplified. Conventionally, the input signal and the pump are combined into one physical port using an external pump coupler, such as an SMA-connectorized directional coupler, from which the combined signal and pump are guided to the amplifier through a cable.
AI-TWPA-C instead directly integrates a pump coupler circuit on the same superconducting chip as the amplifier, thus eliminating a (typically) non-superconducting external pump coupler, an SMA-SMA connector interface, and one cable. This saves 0.5-1 dB of insertion loss between the signal source and the input of the amplifier, directly translating to an increase of quantum efficiency by a factor of 1.12-1.26.
From an end user perspective, the main advantage of three-wave-mixing TWPAs is that the pump frequency is far above the signal band. The large frequency separation makes it relatively easy to filter out the pump tone while adding minimal insertion loss at signal frequencies, using e.g. low-pass filters. It also provides more flexibility for implementing pump couplers (integrated inside AI-TWPA-C). In contrast, the pump frequency is at the center of the signal band in four-wave-mixing TWPAs.
Three-wave mixing is also at the heart of some of our circuit design details, but ultimately this manifests itself to the end user mainly as excellent bandwidth, noise and dynamic range, rather than specific additional features.
Three-wave-mixing TWPAs require quasi-static magnetic flux biasing or current biasing. Conventionally, the magnetic bias is provided by a macroscopic coil placed near the amplifier chip. In AI-TWPA-C, this bias is instead created with an on-chip flux bias line, which provides excellent uniformity and repeatability of the flux bias, even when moving the amplifier to another setup. Together with the long-term stability of AI-TWPA-C, this addresses the concern about complexity of tune-up that comes with an additional tuning parameter (dc flux or current bias), which has historically been an issue in the context of academic research on the topic, where repeatability and stability of device fabrication has been limited. This historical lack of stability has favored less-ambitious dc-bias-free four-wave-mixing designs, at the expense of other desirable features and performance (see above).
Furthermore, the integrated flux line generates minimal off-chip fringing fields, making dense integration of more than one amplifier possible, without requiring individual magnetic shielding.
The RF connectors are SMP (signal in, signal out, pump) and the current to the integrated flux line is provided through a pair of MMCX connectors. We provide all the required cables.
It is important to define the reference plane for the input when talking about quantum efficiency.
If you consider the quantum efficiency referred to the input of AI-TWPA-C, as is common in literature on amplifiers, the efficiency is ca. 70% or greater, corresponding to added noise of less than one photon. The standard quantum limit is half a photon so this noise level is extremely low. We measure the added noise over the full signal band for every AI-TWPA-C we ship, using a broadband thermal noise source.
In the context of superconducting qubits, the term quantum efficiency is often used to refer to the quantum efficiency referred to the qubit chip, or more specifically the readout resonator on the qubit chip. This takes into account insertion loss between the readout resonator and the amplifier, which is generally more relevant for the ultimate application, but also makes the quantity highly dependent on details of the qubit chip, its packaging, auxiliary components and quality of wiring and connectors.
For small quantities (up to five units), we usually offer AI-TWPA-C and its accessories off the shelf. In such cases, you can expect to receive your order within 1–3 weeks, depending on your country.
For larger quantities, we’re capable of delivering tens of units in a matter of weeks and hundreds in a matter of months. If you have an urgent need, please contact us and we’ll do our best to support you.
As part of our support, we provide a detailed step-by-step setup guide that includes several intermediate reference measurements, and example data, that you can use to verify that the amplifier is operating in your setup as it should. We also provide a test report containing gain, added noise and dynamic range measurements for each AI-TWPA-C we deliver, which you can use for direct comparison.
Gain-bandwidth product is a useful quantity for relatively simple resonant parametric amplifiers where it describes the inverse proportionality of gain and bandwidth reasonably well. In traveling-wave parametric amplifiers, including AI-TWPA-C, we could define such a quantity for a given operation point (e.g. ~5 GHz x 15 dB), but it does not remain constant if we move toward higher or lower gain. In fact, the bandwidth of AI-TWPA-C has little dependence on gain, and instead the main trade-off is between gain and gain ripple.
Currently, the most common application is readout of superconducting qubits, such as transmon or fluxonium qubits. More specifically, so-called dispersive readout in circuit quantum electrodynamics (cQED) requires near-quantum-limited amplifiers for fast, high-fidelity quantum-non-demolition (QND) readout. Other variants of this use case include the study of qubits coupled directly to waveguides (“waveguide QED”).
Low-power quality factor measurements of linear high-Q resonators is another use case, as such measurements become slower and slower as the quality of the resonators improves. These studies are integral in efforts to engineer high-coherence time qubits.
A high-level overview is shown in the wiring diagram on the Product page. We provide more detailed information together with our quotes, including a complete readout chain reference implementation. After your purchase, we offer support for installation and tune-up, as a standard part of our process.
Whether you are a researcher looking for an individual TWPA or a company needing a reliable supplier for thousands of amplifiers, we are delighted to discuss your application needs and make an offer.