A reversed Kerr traveling wave parametric amplifier

Abstract A Josephson traveling-wave parametric amplifier (JTWPA) is indispensable for the high-fidelity readout of superconducting qubits, owing to its broadband gain and near-quantum-limited noise performance. Conventional JTWPAs implemented with 0-Josephson junctions (0-JTWPAs) avoid magnetic-flux bias but rely on Kerr nonlinearity, which leads to pump-power-dependent phase mismatch, gain ripple, and a limited dynamic range. More recently, three-wave-mixing (3WM) JTWPAs employing flux-biased rf-SQUIDs have been proposed to suppress Kerr effects. However, these designs require a significant external flux bias per unit cell, which complicates cryogenic hardware, introduces sensitivity to flux noise, and limits scalability in large arrays. In this study, we propose and analyze a π -junction-based JTWPA ( π -JTWPA) in which the intrinsic π phase shift of the junction effectively displaces the operating point of the current–phase relation. This approach aims to realize 3WM-type nonlinearity with reduced flux bias while preserving broadband amplification, thereby simplifying flux-bias distribution, enhancing robustness against flux noise, and providing a pathway toward scalable, multiplexed quantum readout architectures. In addition, we examine the potential applicability of the π -JTWPA in four-wave-mixing (4WM) operation.Abstract A Josephson traveling-wave parametric amplifier (JTWPA) is indispensable for the high-fidelity readout of superconducting qubits, owing to its broadband gain and near-quantum-limited noise performance. Conventional JTWPAs implemented with 0-Josephson junctions (0-JTWPAs) avoid magnetic-flux bias but rely on Kerr nonlinearity, which leads to pump-power-dependent phase mismatch, gain ripple, and a limited dynamic range. More recently, three-wave-mixing (3WM) JTWPAs employing flux-biased rf-SQUIDs have been proposed to suppress Kerr effects. However, these designs require a significant external flux bias per unit cell, which complicates cryogenic hardware, introduces sensitivity to flux noise, and limits scalability in large arrays. In this study, we propose and analyze a π -junction-based JTWPA ( π -JTWPA) in which the intrinsic π phase shift of the junction effectively displaces the operating point of the current–phase relation. This approach aims to realize 3WM-type nonlinearity with reduced flux bias while preserving broadband amplification, thereby simplifying flux-bias distribution, enhancing robustness against flux noise, and providing a pathway toward scalable, multiplexed quantum readout architectures. In addition, we examine the potential applicability of the π -JTWPA in four-wave-mixing (4WM) operation.

Journal of Physics Conference SeriesJul 1, 20260 citations

Single-Mode Squeezing Using Degenerate Four-Wave Mixing in a Dual-Pump TWPA

Anna Levochkina, Kirill Petrovnin, Iiro Harju +2 more

Single-mode squeezing of the electromagnetic vacuum is a key resource for mode-selective noise reduction in quantum measurements. At microwave frequencies, single-mode squeezing is typically obtained by using Josephson and Traveling-Wave Parametric Amplifiers designed for three-wave mixing operation. In single-pump degenerate four-wave mixing, the coincidence of pump, signal, and idler frequencies complicates separation of the squeezed field from the strong pump. A dual-pump configuration enables degenerate operation while keeping both pumps spectrally separated from the squeezed mode. Here, we demonstrate single-mode squeezing in a flux-tunable, dual-pump Traveling-Wave Parametric Amplifier, employing reversed-Kerr phase matching. By independently calibrating the single-pump gains, we find that the strongest squeezing occurs along approximately balanced-gain trajectories, while the optimal squeezing does not necessarily correspond to the highest dual-pump gain. At flux biases $Φ_\mathrm{ext}/Φ_0 = 0.0$ and $0.5$ , the minimum quadrature noise levels reach $-2.48 \pm 0.18~\mathrm{dB}$ and $-1.62 \pm 0.20~\mathrm{dB}$ relative to vacuum, respectively. These results establish the proposed architecture as a platform for single-mode squeezing in microwave continuous-variable quantum technologies.Single-mode squeezing of the electromagnetic vacuum is a key resource for mode-selective noise reduction in quantum measurements. At microwave frequencies, single-mode squeezing is typically obtained by using Josephson and Traveling-Wave Parametric Amplifiers designed for three-wave mixing operation. In single-pump degenerate four-wave mixing, the coincidence of pump, signal, and idler frequencies complicates separation of the squeezed field from the strong pump. A dual-pump configuration enables degenerate operation while keeping both pumps spectrally separated from the squeezed mode. Here, we demonstrate single-mode squeezing in a flux-tunable, dual-pump Traveling-Wave Parametric Amplifier, employing reversed-Kerr phase matching. By independently calibrating the single-pump gains, we find that the strongest squeezing occurs along approximately balanced-gain trajectories, while the optimal squeezing does not necessarily correspond to the highest dual-pump gain. At flux biases $Φ_\mathrm{ext}/Φ_0 = 0.0$ and $0.5$, the minimum quadrature noise levels reach $-2.48 \pm 0.18~\mathrm{dB}$ and $-1.62 \pm 0.20~\mathrm{dB}$ relative to vacuum, respectively. These results establish the proposed architecture as a platform for single-mode squeezing in microwave continuous-variable quantum technologies.

quant-pharXiv:2611.00934Nov 3, 2026

Superinductor Based Traveling Wave Parametric Amplifier

Matthew Bell, Ana Samolov

Bulletin of the American Physical SocietyMar 3, 20150 citations

A travelling-wave parametric amplifier isolator

Arpit Ranadive, Bekim Fazliji, Gwenael Le Gal +8 more

Nature ElectronicsNov 14, 202512 citations

Φ_\mathrm{ext}/Φ_0 = 0.0

and

0.5

, the minimum quadrature noise levels reach

-2.48 \pm 0.18~\mathrm{dB}

and

-1.62 \pm 0.20~\mathrm{dB}

relative to vacuum, respectively. These results establish the proposed architecture as a platform for single-mode squeezing in microwave continuous-variable quantum technologies.