Single-shot qubit readout in circuit quantum electrodynamics

By F. Mallet, F. Ong, A. Palacios-Laloy, F. Nguyen, P. Bertet, D. Vion, Daniel Estève. 2009

265 citations recorded by the source corpus.

The ‘transmon’ design for superconducting qubits is particularly promising, owing to the long coherence times that it enables. Now, high-fidelity single-shot readout of such qubits — necessary for operating a quantum processor — has been demonstrated The future development of quantum information using superconducting circuits requires Josephson qubits1 with long coherence times combined with a high-fidelity readout. Significant progress in the control of coherence has recently been achieved using circuit quantum electrodynamics architectures2,3, where the qubit is embedded in a coplanar waveguide resonator, which both provides a well-controlled electromagnetic environment and serves as qubit readout. In particular, a new qubit design, the so-called transmon, yields reproducibly long coherence times4,5. However, a high-fidelity single-shot readout of the transmon, desirable for running simple quantum algorithms or measuring quantum correlations in multi-qubit experiments, is still lacking. Here, we demonstrate a new transmon circuit where the waveguide resonator is turned into a sample-and-hold detector—more specifically, a Josephson bifurcation amplifier6,7—which allows both fast measurement and single-shot discrimination of the qubit states. We report Rabi oscillations with a high visibility of 94%, together with dephasing and relaxation times longer than 0.5 μs. By carrying out two measurements in series, we also demonstrate that this new readout does not induce extra qubit relaxation.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/4c310751bddce6a263c3cd6b9f6a23f69ec19871

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Citations in the corpus

Rapid High-Fidelity Single-Shot Dispersive Readout of Superconducting Qubits (2017, background): “While averaging was required early on to determine the qubit state [11], advances in quantum limited amplification [12–15] allowed for the observation of quantum jumps and the discrimination of qubit states in single shot measurements [16, 17].”
Noiseless non-reciprocity in a parametric active device (2010, unknown): “We begin by deriving the scattering matrix of the UDC stage and obtain (see the equations (5) and (6) of Methods section)  a0 out a0 out b+ b− =  r0 −q0 tde sde q0 r0 itde −isde tue −itue r+ 0 −sue −isue 0 r−   a0 ′ in a0 ′′ in b+ in b− ”
Demonstration of quantum volume 64 on a superconducting quantum computing system (2020, methodology): “In section 2 we give an overview of the ibmq_montreal device, which is a 27-qubit IBM Quantum Falcon processor; in section 3 we discuss the improvements to the compiler; in section 4 we discuss the dynamical decoupling protocol; in section 5 we discuss the faster implementation of the direct CNOT ga”
Circuit QED: Superconducting Qubits Coupled to Microwave Photons (2015, methodology): “The Josephson bifurcation amplifier, and its cousin the cavity bifurcation amplifier, (Siddiqi et al., 2004; Metcalfe et al., 2007; Mallet et al., 2009) use a large Josephson junction as the non-linear element.”
Circuit quantum electrodynamics (2020, background): “…to exploit the fact that the low- and high-photonnumber states can be easily distinguished to realize highfildelity single-shot qubit readout (Mallet et al., 2009). b. High-power readout and qubit ’punch out’ Coming back to linear resonators, while the non-QNDness at moderate measurement…”
Rapid High-fidelity Multiplexed Readout of Superconducting Qubits (2018, background): “Recent improvements in the efficiency of microwave parametric amplifiers [14–17] have enabled single-shot dispersive qubit readout with high fidelity [18, 19].”