We demonstrate K-band nondegenerate three-wave-mixing amplification in a multimode resonator comprising an array of 500 SNAILs. Pairing K-band signal modes with lower-frequency internal idler modes enables 20 dB of gain continuously from 19.6 to 25.6 GHz with pump frequencies below 32.2 GHz. At 20 dB gain, the 3-dB bandwidth ranges from 2.6 to 11.7 MHz, and the input-referred 1-dB compression power reaches -100.9 dBm. In the 20-22 GHz band, the average added noise is 0.73 quanta. A two-mode nondegenerate parametric amplification model describes the measured gain response and gain-bandwidth behavior, while a multimode Kerr model captures the overall compression scale. Our amplifier provides a practical solution for implementing a state-of-the-art readout of superconducting qubits in the K-band.
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6 pages, 4 figures; 3 pages of supplementary material
We demonstrate K-band nondegenerate three-wave-mixing amplification in a multimode resonator comprising an array of 500 SNAILs. Pairing K-band signal modes with lower-frequency internal idler modes enables 20 dB of gain continuously from 19.6 to 25.6 GHz with pump frequencies below 32.2 GHz. At 20 dB gain, the 3-dB bandwidth ranges from 2.6 to 11.7 MHz, and the input-referred 1-dB compression power reaches -100.9 dBm. In the 20-22 GHz band, the average added noise is 0.73 quanta. A two-mode nondegenerate parametric amplification model describes the measured gain response and gain-bandwidth behavior, while a multimode Kerr model captures the overall compression scale. Our amplifier provides a practical solution for implementing a state-of-the-art readout of superconducting qubits in the K-band.
We introduce a near-quantum-limited amplifier with a large tunable bandwidth and high dynamic range---the Josephson array-mode parametric amplifier (JAMPA). The signal and idler modes involved in the amplification process are realized by the array modes of a chain of 1000 flux-tunable Josephson-junction-based nonlinear elements. The frequency spacing between the array modes is comparable to the flux tunability of the modes, ensuring that any desired frequency can be occupied by a resonant mode, which can further be pumped to produce high gain. We experimentally demonstrate that the device can be operated as a nearly quantum-limited parametric amplifier with 20 dB of gain at almost any frequency within a 4--12-GHz band. On average, it has a 3-dB bandwidth of 11 MHz and an input 1-dB compression power of $\ensuremath{-}108\phantom{\rule{0.2em}{0ex}}\mathrm{dBm}$, which can go as high as $\ensuremath{-}93\phantom{\rule{0.2em}{0ex}}\mathrm{dBm}$. We envision the application of such a device to the time- and frequency-multiplexed readout of multiple qubits, as well as to the generation of continuous-variable cluster states.
Parametric amplification is essential for quantum measurement, enabling the amplification of weak microwave signals with minimal added noise. While Josephson-junction-based amplifiers have become standard in superconducting quantum circuits, their magnetic sensitivity, limited saturation power, and sub-kelvin operating requirements motivate the development of alternative nonlinear platforms. Here we demonstrate a two-mode kinetic-inductance parametric amplifier based on a pair of capacitively coupled Kerr-nonlinear resonators fabricated from NbTiN and NbN thin films. The distributed Kerr nonlinearity of these materials enables nondegenerate four-wave-mixing amplification with gains approaching 40 dB, gain-bandwidth products up to 6.9 MHz, and 1-dB compression powers two to three orders of magnitude higher than those of state-of-the-art Josephson amplifiers. A coupled-mode theoretical model accurately captures the pump-induced modification of the hybridized modes and quantitatively reproduces the observed signal and idler responses. The NbN device exhibits a significantly larger Kerr coefficient and superior gain-bandwidth performance, highlighting the advantages of high-kinetic-inductance materials. Our results establish coupled kinetic-inductance resonators as a robust platform for broadband, high-power, and magnetically resilient quantum-limited amplification, offering a scalable route for advanced readout in superconducting qubits, spin ensembles, quantum dots, and other microwave-quantum technologies.
Josephson parametric amplifiers are an important part of a modern superconducting quantum computing platform and squeezed quantum states generation devices. Traveling wave and impedance-matched parametric amplifiers provide broad bandwidth for high-fidelity single-shot readout of multiple qubit superconducting circuits. Here, we present a quantum-limited 3-wave-mixing parametric amplifier based on superconducting nonlinear asymmetric inductive elements (SNAILs), whose useful bandwidth is enhanced with an on-chip two-section impedance-matching circuit based on microstrip transmission lines. The amplifier dynamic range is increased using an array of 67 SNAILs with 268 Josephson junctions, forming a nonlinear quarter-wave resonator. Operating in a current-pumped mode, we experimentally demonstrate an average gain of 17 dB across 300 MHz bandwidth, along with an average saturation power of –100 dBm, which can go as high as −97 dBm with quantum-limited noise performance. Moreover, the amplifier can be fabricated using a simple technology with just one e-beam lithography step.
Advancing superconducting quantum devices to higher operating frequencies broadens their functionality and enables operation at elevated temperatures, but it also requires near-quantum-limited amplifiers beyond the few-gigahertz regime. Here we present a junction-free, kinetic-inductance parametric amplifier based on thin-film niobium nitride (NbN) operating at 23 GHz in the microwave K-band, achieving a gain up to 40 dB, a 100 MHz gain-bandwidth product, a 1 dB saturation input power of -85 dBm with 23 dB gain, and added noise no greater than 1.4 quanta for phase-preserving amplification. Leveraging the large superconducting gap of NbN, this architecture can be extended to even higher frequencies, supporting applications such as high-fidelity readout of millimeter-wave superconducting qubits and axion searches over an expanded mass window.
Advancing superconducting quantum devices to higher operating frequencies broadens their functionality and enables operation at elevated temperatures, but it also requires near-quantum-limited amplifiers beyond the few-gigahertz regime. Here, we present a junction-free, kinetic-inductance parametric amplifier based on thin-film niobium nitride (NbN) operating at 23 GHz in the microwave K-band, achieving a gain up to 40 dB, a 100 MHz gain–bandwidth product, a 1 dB saturation input power of −85 dBm with 23 dB gain, and added noise not greater than 1.4 quanta for phase-preserving amplification. Leveraging the large superconducting gap of NbN, this architecture can be extended to even higher frequencies, supporting applications such as high-fidelity readout of millimeter-wave superconducting qubits and axion searches over an expanded mass window.
We have developed and measured a high-gain quantum-limited microwave parametric amplifier based on a superconducting lumped LC resonator with the inductor L including an array of eight superconducting quantum interference devices (SQUIDs). This amplifier is parametrically pumped by modulating the flux threading the SQUIDs at twice the resonator frequency. Around 5 GHz, a maximum gain of 31 dB, a product amplitude gain $\ifmmode\times\else\texttimes\fi{}$ bandwidth above 60 MHz, and a 1 dB compression point of $\ensuremath{-}123$ dBm at 20 dB gain are obtained in the nondegenerate mode of operation. Phase-sensitive amplification-deamplification is also measured in the degenerate mode and yields a maximum gain of 37 dB. The compression point obtained is 18 dB above what would be obtained with a single SQUID of the same inductance, due to the smaller nonlinearity of the SQUID array.