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The future development of quantum information using superconducting circuits requires Josephson qubits with long coherence times combined to a high-delity readout. Major progress in the control of coherence has recently been achieved using…

We theoretically investigate a readout scheme of the quantum state of a superconducting qubit based on time delay of a single flux quantum (SFQ), also known as a fluxon, propagating in a Josephson transmission line (JTL). We concretely…

Quantum Physics · Physics 2026-03-16 Shunsuke Kamimura , Aree Taguchi , Masamitsu Tanaka , Tsuyoshi Yamamoto

Silicon spin qubits based on metal-oxide-semiconductor (MOS) technology are compatible with semiconductor manufacturing and offer a route to scalable quantum processing. However, spin readout typically relies on proximal charge sensors,…

We study how single-qubit dispersive readout works alongside two qubit coupling. To make calculations analytically tractable, we use a simplified model which retains core characteristics of but is discretised compared to dispersive homodyne…

Quantum Physics · Physics 2020-09-24 Joel C. Pommerening , David P. DiVincenzo

We propose and demonstrate transmission-based dispersive readout of a superconducting qubit using an all-pass resonator, which preferentially emits readout photons toward the output. This is in contrast to typical readout schemes, which…

We have fabricated a Josephson charge qubit by capacitively coupling a single-Cooper-pair box (SCB) to an electrometer based upon a single-electron transistor configured for radio-frequency readout (RF-SET). Charge quantization of 2e is…

Superconductivity · Physics 2009-11-10 T. Duty , D. Gunnarsson , K. Bladh , P. Delsing

Sensitive charge detection has enabled qubit readout in solid-state systems. Recently, an alternative to the well-established charge detection via on-chip electrometers has emerged, based on in situ gate detectors and radio-frequency…

Mesoscale and Nanoscale Physics · Physics 2017-05-24 A. Rossi , R. Zhao , A. S. Dzurak , M. F. Gonzalez-Zalba

We control transition frequency of a superconducting flux qubit coupled to a frequency-tunable resonator comprising a direct current superconducting quantum interference device (dc-SQUID) by microwave driving. The dc-SQUID mediates the…

Quantum Physics · Physics 2020-09-08 Hiraku Toida , Takuya Ohrai , Yuichiro Matsuzaki , Kosuke Kakuyanagi , Shiro Saito

We report measurements on two superconducting flux qubits coupled to a readout Superconducting QUantum Interference Device (SQUID). Two on-chip flux bias lines allow independent flux control of any two of the three elements, as illustrated…

Superconductivity · Physics 2009-11-11 B. L. T. Plourde , T. L. Robertson , P. A. Reichardt , T. Hime , S. Linzen , C. -E. Wu , John Clarke

Quantum computation requires high-fidelity qubit readout, preserving the quantum state. In the case of superconducting (SC) qubits, readout is typically performed using a complex analog experimental setup operated at room temperature, which…

High fidelity qubit readout is a cornerstone for quantum information protocols. In traditional superconducting qubit readout, a chain of microwave amplifiers and nonreciprocal components aid in detecting the qubit's state with tolerable…

Quantum Physics · Physics 2026-03-16 B. T. Miller , Lindsay Orr , A. Metelmann , F. Lecocq

Fast and high-fidelity qubit measurement is crucial for achieving quantum error correction, a fundamental element in the development of universal quantum computing. For electron spin qubits, fast readout stands out as a major obstacle in…

Mesoscale and Nanoscale Physics · Physics 2024-01-09 Chon-Fai Kam , Xuedong Hu

We describe the read-out process of the state of a Josephson flux qubit via solitons in Josephson transmission lines (JTL) as they are in use in the standard rapid single flux quantum (RSFQ) technology. We consider the situation where the…

Superconductivity · Physics 2007-06-18 Arkady Fedorov , Alexander Shnirman , Gerd Schön , Anna Kidiyarova-Shevchenko

We perform readout of a quantum-dot hybrid qubit coupled to a superconducting resonator through a parametric, longitudinal interaction mechanism. Our experiments are performed with the qubit and resonator frequencies detuned by $\sim$10…

We replace the Josephson junction defining a three-junction flux qubit's properties with a tunable direct current superconducting quantum interference devices (DC-SQUID) in order to tune the qubit gap during the experiment. We observe…

Superconductivity · Physics 2015-05-19 Xiaobo Zhu , Alexander Kemp , Shiro Saito , Kouichi Semba

The scalable application of quantum information science will stand on reproducible and controllable high-coherence quantum bits (qubits). Here, we revisit the design and fabrication of the superconducting flux qubit, achieving a planar…

Single-shot readout experiments were performed on the two lowest-energy states of a superconducting qubit with three Josephson junctions embedded in a superconducting loop. We measured the qubit state via switching current Isw of a…

Superconductivity · Physics 2007-05-23 Hirotaka Tanaka , Shiro Saito , Hayato Nakano , Kouichi Semba , Masahito Ueda , Hideaki Takayanagi

The speed and fidelity of dispersive readout of superconducting qubits should improve by increasing the amplitude of the measurement drive. Experiments show, however, that beyond some drive amplitude there is always a saturation or drop in…

Frequency-selective readout for superconducting qubits opens the way towards scaling qubit circuits up without increasing the number of measurement lines. Here we demonstrate the readout of an array of 7 flux qubits located on the same…

Superconductivity · Physics 2015-05-27 M. Jerger , S. Poletto , P. Macha , U. Huebner , A. Lukashenko , E. Il'ichev , A. V. Ustinov

Silicon spin qubits have emerged as a promising path to large-scale quantum processors. In this prospect, the development of scalable qubit readout schemes involving a minimal device overhead is a compelling step. Here we report the…

Mesoscale and Nanoscale Physics · Physics 2019-07-09 A. Crippa , R. Ezzouch , A. Aprá , A. Amisse , L. Houtin , B. Bertrand , M. Vinet , M. Urdampilleta , T. Meunier , M. Sanquer , X. Jehl , R. Maurand , S. De Franceschi