Transmon qubit readout fidelity at the threshold for quantum error correction
without a quantum-limited amplifier

Chen, Liangyu; Li, Hang-Xi; Lu, Yonghua; Warren, Christopher; Križan, Christian; Kosen, Sandoko; Rommel, Marcus; Ahmed, Shahnawaz; Osman, Amr; Biznárová, Janka; Roudsari, Anita Fadavi; Lienhard, Benjamin; Caputo, Marco; Grigoras, Kestutis; Grönberg, Leif; Govenius, Joonas; Kockum, Anton Frisk; Delsing, Per; Bylander, Jonas; Tancredi, Giovanna

doi:10.21203/rs.3.rs-1953331/v1

Cited by 3 publications

(3 citation statements)

References 49 publications

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“…This may enable the use of a power level that the bolometer can detect with a higher SNR, and still maintain the QND nature of the readout. Alternatively, the SNR of the signal reaching the bolometer may be increased by preparing the qubit in a highly excited state before readout 23 , or by using a two-tone drive that induces an effective longitudinal coupling between the qubit and bolometer 41,42 . Data analysis can be improved using optimized signal processing.…”

Section: Discussionmentioning

confidence: 99%

“…Microwave photon counters offer an alternative to voltage amplification at the millikelvin stage, but require a more involved pulse sequence and suffer from backaction arising from the creation of quasiparticles and their tunnelling. Qubit readout can also be achieved without a parametric amplifier by driving the qubit to the second excited state before readout 23 . However, the required non-parametric microwave amplifier introduces high-temperature noise close to the qubit frequency, which necessitates bulky microwave isolators.…”

Section: Articlementioning

confidence: 99%

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Single-shot readout of a superconducting qubit using a thermal detector

Gunyhó,

Kundu,

et al. 2024

Nat Electron

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Measuring the state of a qubit is a key fundamental operation of a quantum computer. High-fidelity single-shot readout of superconducting qubits can be achieved using parametric amplifiers at millikelvin temperatures. However, scaling parametric amplifiers beyond hundreds of qubits is challenging due to practical size and power limitations. Nanobolometers can, in contrast, offer scalability, sensitivity and speed suitable for qubit readout. Here we show that a bolometer can provide single-shot qubit readout with a readout duration of 13.9 μs and a single-shot fidelity of 0.618. The fidelity is mainly limited by the energy relaxation time of the qubit (28 μs), and a fidelity of 0.927 is found after removing errors arising from this relaxation. In the future, higher-fidelity single-shot readout may be achieved through improvements in chip design and experimental setup, as well as a change in the bolometer absorber material to reduce the readout time to the level of hundreds of nanoseconds and below.

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Section: Discussionmentioning

confidence: 99%

Section: Articlementioning

confidence: 99%

Single-shot readout of a superconducting qubit using a thermal detector

Gunyhó,

Kundu,

et al. 2024

Nat Electron

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“…This continuous evolution signifies a substantial leap forward in the ongoing enhancement of superconducting qubit technologies. The quest to enhance the quality of information processing has ignited focused efforts to fine-tune the measurement techniques applied to qubits and resonators 15 .…”

Section: Background and Summarymentioning

confidence: 99%

Optimizing Qubit Performance through Smoothing Techniques

Malashin,

Masich,

Tynchenko

et al. 2024

Preprint

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This study explores novel approach to enhance the performance of qubits by leveraging signal smoothing algorithms to qubit chips, aiming primarily to mitigate experimental variability and enhance overall stability. This effort is intricately tied to the improvement of the Hamiltonian spectrum. By optimizing qubit operation through advanced smoothing techniques, we not only extend coherence times but also ascertain the robustness and quality of the qubit. Our findings highlight a substantial improvement in the precision of quantum information processing, indicating enhanced reliability in quantum computing experiments. Please note: Abbreviations should be introduced at the first mention in the main text – no abbreviations lists. Suggested structure of main text (not enforced) is provided below.

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Bifurcation Oscillator as an Advanced Sensor for Quantum State Control

Pashin

Bastrakova

Satanin

et al. 2022

Sensors

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We study bifurcation behavior of a high-quality (high-Q) Josephson oscillator coupled to a superconducting qubit. It is shown that the probability of capture into the state of dynamic equilibrium is sensitive to qubit states. On this basis we present a new measurement method for the superposition state of a qubit due to its influence on transition probabilities between oscillator levels located in the energy region near the classical separatrix. The quantum-mechanical behavior of a bifurcation oscillator is also studied, which makes it possible to understand the mechanism of "entanglement" of oscillator and qubit states during the measurement process. The optimal parameters of the driving current and the state of the oscillator are found for performing one-qubit gates with the required precision, when the influence on the qubit from measurement back-action is minimal. A measurement protocol for state populations of the qubit entangled with the oscillator is presented.

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Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier

Cited by 3 publications

References 49 publications

Single-shot readout of a superconducting qubit using a thermal detector

Single-shot readout of a superconducting qubit using a thermal detector

Optimizing Qubit Performance through Smoothing Techniques

Bifurcation Oscillator as an Advanced Sensor for Quantum State Control

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