Broadband Squeezed Microwaves and Amplification with a Josephson Traveling-Wave Parametric Amplifier

Generation and structuring of multipartite entanglement in Josephson parametric system

“…The basic parametric microwave setting allows for enhancement in the number of spectral modes by additional pump tones, which leads to generation of more complex, entangled H-graph states. Enhanced number of modes requires larger bandwidth, which calls for broadband parametric devices such as TWPAs [43][44][45][46][47] or broadband JPAs [42,48] in order to avoid problems with spectral mode crowding.…”

“…The limiting factors are the requirements of high precision for the pump frequency and its phase, the stability of the biasing flux, and possible crowding of modes within a narrow-band JPA resonance. However, recently it has been demonstrated that entanglement can be generated in low-loss traveling wave parametric amplifiers [45][46][47]. This opens a way to significant increase in the number of entangled modes.…”

“…Furthermore, by tuning the phases of the pumps, the state can be converted into square-lattice H-graph state. With the bandwidth improvements provided by the state-ofthe-art superconducting parametric devices, such as the broadband, low-loss travelling wave parametric amplifier [45][46][47], we expect a substantial increase in the number of entangled modes, which facilitates generation of highlysqueezed square-lattice H-graph states for CV quantum computation at microwave frequencies.…”

Propagating Quantum Microwaves: Towards Applications in Communication and Sensing

“…In contrast, three-wave mixing (3WM) TWPAs by device design have the advantage of the pump signal being situated outside the signal band, facilitating easy filtering [40,94]. Recently, a non-degenerate 4WM TWPA with two pump tones has been demonstrated [96], providing multiple GHz of signal bandwidth between the pump tones without sacrificing gain and noise performance. Similarly, 3WM implementations of both JTWPAs [40] and KITWPAs [97] have produced gain in excess of 15 dB in the 4-8 GHz frequency range with near-quantumlimited noise performance in the same frequency band.…”

Magnetic field-resilient quantum-limited parametric amplifier

“…In this measurement, the highest gain is 22 dB and the deamplification is as deep as 18 dB, which is limited by the dynamic range of the digitization instrumentation. The coherent deamplification demonstration suggests the potential for large vacuum squeezing by NKPA, which could be a unique advantage of NKPA compared to Josephson junction-based amplifiers because of the absence of higher-order nonlinearities [9,[41][42][43]. We then go on to verify the quantum-limited ampli-fication of the NKPA by characterizing its added noise as a phase-preserving amplifier.…”