Multi-path interferometric Josephson directional amplifier for qubit readout. (25th January 2018)

• Record Type: Journal Article
• Authors: Abdo, Baleegh; Bronn, Nicholas T; Jinka, Oblesh; Olivadese, Salvatore; Brink, Markus; Chow, Jerry M
• Is Part Of: Quantum science and technology. Volume 3:Number 2(2018)
• Publication Date: 2018-01-25
• Subjects: nonreciprocal devices -- directional amplifiers -- Josephson amplifiers -- qubit readout -- quantum measurement; 84.30.Le -- 42.25.Hz -- 85.25.Cp -- 78.20.Ls; Quantum theory -- Periodicals; Quantum theory; Periodicals; 530
• DOI: 10.1088/2058-9565/aaa1f9
• Languages: English
• ISSNs: 2058-9565

Abstract

Abstract: We realize and characterize a quantum-limited, directional Josephson amplifier suitable for qubit readout. The device consists of two nondegenerate, three-wave-mixing amplifiers that are coupled together in an interferometric scheme, embedded in a printed circuit board. Nonreciprocity is generated by applying a phase gradient between the same-frequency pumps feeding the device, which plays the role of the magnetic field in a Faraday medium. Directional amplification and reflection-gain elimination are induced via wave interference between multiple paths in the system. We measure and discuss the main figures of merit of the device and show that the experimental results are in good agreement with theory. An improved version of this directional amplifier is expected to eliminate the need for bulky, off-chip isolation stages that generally separate quantum systems and preamplifiers in high-fidelity, quantum-nondemolition measurement setups.