Initialization by Measurement of a Superconducting Quantum Bit Circuit

2012/04/11 by D. Ristè, Diego Ristè, J. G. van Leeuwen +4 · 181 citations
Computer Science · Physics and Astronomy · #Circuit quantum electrodynamics #Computer science #Ground state #Initialization #Josephson effect #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum and electron transport phenomena #Quantum mechanics #Qubit #Superconductivity #Transmon #cond-mat.mes-hall #quant-ph

paper · pdf · doi:10.1103/physrevlett.109.050507

published in Physical Review Letters 109(5), 050507 (American Physical Society) · 5 pages, 4 figures, and Supplementary Information (7 figures, 1 table)

arxiv created 2012/04/11 · openalex publication_date 2012/08/03 · arxiv updated 2012/08/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We demonstrate initialization by joint measurement of two transmon qubits in 3D circuit quantum electrodynamics. Homodyne detection of cavity transmission is enhanced by Josephson parametric amplification to discriminate the two-qubit ground state from single-qubit excitations nondestructively and with 98.1% fidelity. Measurement and postselection of a steady-state mixture with 4.7% residual excitation per qubit achieve 98.8% fidelity to the ground state, thus outperforming passive initialization.

Citations

• Tunable joint measurements in the dispersive regime of cavity QED
• Quantum trajectory approach to circuit QED: Quantum jumps and the Zeno effect
• Amplification and squeezing of quantum noise with a tunable Josephson metamaterial
• Controlling the Spontaneous Emission of a Superconducting Transmon Qubit
• Fast reset and suppressing spontaneous emission of a superconducting qubit
• Implementing the Quantum von Neumann Architecture with Superconducting Circuits
• Cavity quantum electrodynamics for superconducting electrical circuits: An architecture for quantum computation
• Strong coupling of a single photon to a superconducting qubit using circuit quantum electrodynamics
• Microwave-Induced Cooling of a Superconducting Qubit
• Spectral measurement of the thermal excitation of a superconducting qubit
• Josephson amplifier for qubit readout
• Coupling superconducting qubits via a cavity bus
• Quantum Computing

Cited by

• Blind Quantum Computation on a Modular Superconducting Processor
• Heralded State Preparation in a Superconducting Qubit

Related

• High-Fidelity Readout in Circuit Quantum Electrodynamics Using the Jaynes-Cummings Nonlinearity
• Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier
• Weak Measurement and Feedback in Superconducting Quantum Circuits
• Tunable joint measurements in the dispersive regime of cavity QED
• 99.9%-fidelity in measuring a superconducting qubit