ArXiv · 2026
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 Φext/Φ₀ = 0.0 and 0.5, the minimum quadrature noise levels reach -2.48 ± 0.18 dB and -1.62 ± 0.20 dB relative to vacuum, respectively. These results establish the proposed architecture as a platform for single-mode squeezing in microwave continuous-variable quantum technologies.
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