2014/07/25 by Z. R. Lin, Zhirong Lin, K. Inomata +9 · 93 citations
Computer Science · Physics and Astronomy · #Computer science #Demodulation #Josephson effect #Microwave #Optoelectronics #Phase qubit #Physics #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum and electron transport phenomena #Quantum mechanics #Qubit #Resonator #Superconductivity #Telecommunications #Transmon #cond-mat.mes-hall #cond-mat.supr-con #quant-ph
paper · pdf · doi:10.1038/ncomms5480
published in Nature Communications 5(1), 4480 (Nature Portfolio) · 15 pages, 11 figures, including supplementary material
openalex publication_date 2014/07/25 · arxiv created 2014/07/27 · arxiv updated 2015/06/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The parametric phase-locked oscillator (PPLO), also known as a parametron, is a resonant circuit in which one of the reactances is periodically modulated. It can detect, amplify, and store binary digital signals in the form of two distinct phases of self-oscillation. Indeed, digital computers using PPLOs based on a magnetic ferrite ring or a varactor diode as its fundamental logic element were successfully operated in 1950s and 1960s. More recently, basic bit operations have been demonstrated in an electromechanical resonator, and an Ising machine based on optical PPLOs has been proposed. Here, using a PPLO realized with Josephson-junction circuitry, we demonstrate the demodulation of a microwave signal digitally modulated by binary phase-shift keying. Moreover, we apply this demodulation capability to the dispersive readout of a superconducting qubit. This readout scheme enables a fast and latching-type readout, yet requires only a small number of readout photons in the resonator to which the qubit is coupled, thus featuring the combined advantages of several disparate schemes. We have achieved high-fidelity, single-shot, and non-destructive qubit readout with Rabi-oscillation contrast exceeding 90%, limited primarily by the qubit's energy relaxation.