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High-Fidelity Readout in Circuit Quantum Electrodynamics Using the Jaynes-Cummings Nonlinearity

2010; American Physical Society; Volume: 105; Issue: 17 Linguagem: Inglês

10.1103/physrevlett.105.173601

1092-0145

Matthew D. Reed, L. DiCarlo, Blake Johnson, Luyan Sun, David Schuster, Luigi Frunzio, Robert Schoelkopf,

Quantum Computing Algorithms and Architecture

We demonstrate a qubit readout scheme that exploits the Jaynes-Cummings nonlinearity of a superconducting cavity coupled to transmon qubits. We find that in the strongly-driven dispersive regime of this system, there is the unexpected onset of a high-transmission "bright" state at a critical power which depends sensitively on the initial qubit state. A simple and robust measurement protocol exploiting this effect achieves a single-shot fidelity of 87% using a conventional sample design and experimental setup, and at least 61% fidelity to joint correlations of three qubits.