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Fast, Lifetime-Preserving Readout for High-Coherence Quantum Annealers
- Source :
- PRX Quantum 1, 020314 (2020)
- Publication Year :
- 2020
-
Abstract
- We demonstrate, for the first time, that a quantum flux parametron (QFP) is capable of acting as both isolator and amplifier in the readout circuit of a capacitively shunted flux qubit (CSFQ). By treating the QFP like a tunable coupler and biasing it such that the coupling is off, we show that $T_1$ of the CSFQ is not impacted by Purcell loss from its low-Q readout resonator ($Q_e = 760$) despite being detuned by only $40$ MHz. When annealed, the QFP amplifies the qubit's persistent current signal such that it generates a flux qubit-state-dependent frequency shift of $85$ MHz in the readout resonator, which is over $9$ times its linewidth. The device is shown to read out a flux qubit in the persistent current basis with fidelities surpassing $98.6\%$ with only $80$ ns integration, and reaches fidelities of $99.6\%$ when integrated for $1$ $\mu$s. This combination of speed and isolation is critical to the readout of high-coherence quantum annealers.<br />Comment: 14 pages, 11 figures; version accepted for publication in PRX Quantum
- Subjects :
- Quantum Physics
Subjects
Details
- Database :
- arXiv
- Journal :
- PRX Quantum 1, 020314 (2020)
- Publication Type :
- Report
- Accession number :
- edsarx.2006.10817
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PRXQuantum.1.020314