Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1209.1781 · Applied Physics Letters

Multiplexed dispersive readout of superconducting phase qubits

Yu Chen, D. Sank, P. J. J. O’Malley, T. White, R. Barends, B. Chiaro, J. Kelly, Erik A. Lucero, M. Mariantoni, A. Megrant, Charles Neill, A. Vainsencher, J. Wenner, Yue Yin, Andrew N. Cleland, John M. Martinis

Published Oct 29, 2012• 89 citations
arXivHTMLPDF

Abstract

We introduce a frequency-multiplexed readout scheme for superconducting phase qubits. Using a quantum circuit with four phase qubits, we couple each qubit to a separate lumped-element superconducting readout resonator, with the readout resonators connected in parallel to a single measurement line. The readout resonators and control electronics are designed so that all four qubits can be read out simultaneously using frequency multiplexing on the one measurement line. This technology provides a highly efficient and compact means for reading out multiple qubits, a significant advantage for scaling up to larger numbers of qubits.

DOI
10.1063/1.4764940

Related papers

Frequency division multiplexing readout and simultaneous manipulation of an array of flux qubits

Markus Jerger, Stefano Poletto, P. Macha +3 more

An important desired ingredient of superconducting quantum circuits is a readout scheme whose complexity does not increase with the number of qubits involved in the measurement. Here, we present a readout scheme employing a single microwave line, which enables simultaneous readout of multiple qubits. Consequently, scaling up superconducting qubit circuits is no longer limited by the readout apparatus. Parallel readout of 6 flux qubits using a frequency division multiplexing technique is demonstrated, as well as simultaneous manipulation and time resolved measurement of 3 qubits. We discuss how this technique can be scaled up to read out hundreds of qubits on a chip.

arXiv:1205.6375•Applied Physics Letters•Jul 23, 2012•98 citations

Dispersive readout scheme for a Josephson phase qubit

Wirth, Tobias

We present experimental results on a dispersive scheme for reading out a Josephson phase qubit. A capacitively shunted dc-SQUID is used as a nonlinear resonator which is inductively coupled to the qubit. We detect the flux state of the qubit by measuring the amplitude and phase of a microwave pulse reflected from the SQUID resonator. By this low-dissipative method, we reduce the qubit state measurement time down to 25 microseconds, which is much faster than using the conventional readout performed by switching the SQUID to its non-zero dc voltage state. The demonstrated readout scheme allows for reading out multiple qubits using a single microwave line by employing frequency-division multiplexing.

Verhandlungen der Deutschen Physikalischen Gesellschaft•Jan 1, 2011•0 citations

Multiplexing Read-Out of Charge Qubits by a Superconducting Resonator

Tian-Yi Han, Guangwei Deng, Da Wei +1 more

Wavelength division multiplexing (WDM) is widely used in modern optics and electronics. For future quantum computers, the integration of readout is also vitally important. Here we incorporate an idea of WDM to demonstrate multiplexing readout of charge qubits by using a single integrated on-chip superconducting microwave resonator. Two distant qubits formed by two graphene double quantum dots (DQDs) are simultaneously readout by an interconnected superconducting resonator. This readout device is found to have 2 MHz bandwidth and charge sensitivity. Different frequency gate-modulations, which are used selectively to change the impedance of the qubits, are applied to different DQDs, which results in separated sidebands in the spectrum. These sidebands enable a multiplexing readout for the multi-qubits circuit. This architecture can largely reduce the amount of detectors and can improve the prospect for scaling-up of semiconductor qubits.

Chinese Physics Letters•Apr 1, 2016•4 citations

Tunable $LC$ resonator for multiplexed multi-qubit readout

Llorenç Fanals-i-Batllori, Eduard Alarcón, Imran Bashir +3 more

This paper proposes the use of a tunable$LC$resonator to read an array of qubits in a multiplexed fashion, by making the dispersive shift of the targeted qubit dominant. Cavity and circuit electrodynamics (QED) theory is shown to support this idea. The tunable capacitor array, in parallel with a superconducting inductance, is designed to maximize the quality factor by frequency range product,$Q\cdot\Delta\omega$. This approach only requires one RF signal to measure multiple qubits, which can facilitate quantum computing scaling.

IEEE International Symposium on Circuits and Systems proceedings•May 21, 2023•1 citation

Multiplexed readout of superconducting qubits using a three-dimensional reentrant-cavity filter

Mustafa S. Bakr, Simone D Fasciati, Shuxiang Cao +7 more

Hardware-efficient methods for high-fidelity quantum state measurements are crucial for superconducting qubit experiments, as qubit numbers grow and feedback and state reset begin to be employed for quantum error correction. We present a three-dimensional reentrant-cavity filter designed for frequency-multiplexed readout of superconducting qubits. The cavity filter is situated out of the plane of the qubit circuit and capacitively couples to an array of on-chip readout resonators in a manner that can scale to large qubit arrays. The reentrant cavity functions as a large-linewidth bandpass filter with intrinsic Purcell filtering. We demonstrate the concept with a four-qubit multiplexed device in which we achieve an average readout fidelity of 98.6% and measurement-induced crosstalk dephasing rates below 0.15 kHz.

arXiv:2412.14853•Physical Review Applied•May 29, 2025•9 citations

Microwave readout scheme for a Josephson phase qubit

Tobias Wirth, Jürgen Lisenfeld, Alexander V. Lukashenko +1 more

We present experimental results on a microwave scheme for reading out a Josephson phase qubit. A capacitively shunted superconducting quantum interference device (SQUID) is used as a nonlinear resonator which is inductively coupled to the qubit. The flux state of the qubit is detected by measuring the amplitude and phase of a microwave pulse reflected from the SQUID resonator. By this low-dissipative method, the qubit state measurement time is reduced to 25 μs, which is much faster than the conventional readout performed by switching the SQUID to its nonzero dc voltage state. The readout scheme presented here allows for reading out multiple qubits using a single microwave line by employing frequency-division multiplexing.

arXiv:1010.0954•Applied Physics Letters•Dec 27, 2010•13 citations
We introduce a frequency-multiplexed readout scheme for superconducting phase qubits. Using a quantum circuit with four phase qubits, we couple each qubit to a separate lumped-element superconducting readout resonator, with the readout resonators connected in parallel to a single measurement line. The readout resonators and control electronics are designed so that all four qubits can be read out simultaneously using frequency multiplexing on the one measurement line. This technology provides a highly efficient and compact means for reading out multiple qubits, a significant advantage for scaling up to larger numbers of qubits.
An important desired ingredient of superconducting quantum circuits is a readout scheme whose complexity does not increase with the number of qubits involved in the measurement. Here, we present a readout scheme employing a single microwave line, which enables simultaneous readout of multiple qubits. Consequently, scaling up superconducting qubit circuits is no longer limited by the readout apparatus. Parallel readout of 6 flux qubits using a frequency division multiplexing technique is demonstrated, as well as simultaneous manipulation and time resolved measurement of 3 qubits. We discuss how this technique can be scaled up to read out hundreds of qubits on a chip.
We present experimental results on a dispersive scheme for reading out a Josephson phase qubit. A capacitively shunted dc-SQUID is used as a nonlinear resonator which is inductively coupled to the qubit. We detect the flux state of the qubit by measuring the amplitude and phase of a microwave pulse reflected from the SQUID resonator. By this low-dissipative method, we reduce the qubit state measurement time down to 25 microseconds, which is much faster than using the conventional readout performed by switching the SQUID to its non-zero dc voltage state. The demonstrated readout scheme allows for reading out multiple qubits using a single microwave line by employing frequency-division multiplexing.
Wavelength division multiplexing (WDM) is widely used in modern optics and electronics. For future quantum computers, the integration of readout is also vitally important. Here we incorporate an idea of WDM to demonstrate multiplexing readout of charge qubits by using a single integrated on-chip superconducting microwave resonator. Two distant qubits formed by two graphene double quantum dots (DQDs) are simultaneously readout by an interconnected superconducting resonator. This readout device is found to have 2 MHz bandwidth and charge sensitivity. Different frequency gate-modulations, which are used selectively to change the impedance of the qubits, are applied to different DQDs, which results in separated sidebands in the spectrum. These sidebands enable a multiplexing readout for the multi-qubits circuit. This architecture can largely reduce the amount of detectors and can improve the prospect for scaling-up of semiconductor qubits.
Tunable LCLCLC resonator for multiplexed multi-qubit readout
This paper proposes the use of a tunableLCLCLCresonator to read an array of qubits in a multiplexed fashion, by making the dispersive shift of the targeted qubit dominant. Cavity and circuit electrodynamics (QED) theory is shown to support this idea. The tunable capacitor array, in parallel with a superconducting inductance, is designed to maximize the quality factor by frequency range product,Q⋅ΔωQ\cdot\Delta\omegaQ⋅Δω. This approach only requires one RF signal to measure multiple qubits, which can facilitate quantum computing scaling.
Hardware-efficient methods for high-fidelity quantum state measurements are crucial for superconducting qubit experiments, as qubit numbers grow and feedback and state reset begin to be employed for quantum error correction. We present a three-dimensional reentrant-cavity filter designed for frequency-multiplexed readout of superconducting qubits. The cavity filter is situated out of the plane of the qubit circuit and capacitively couples to an array of on-chip readout resonators in a manner that can scale to large qubit arrays. The reentrant cavity functions as a large-linewidth bandpass filter with intrinsic Purcell filtering. We demonstrate the concept with a four-qubit multiplexed device in which we achieve an average readout fidelity of 98.6% and measurement-induced crosstalk dephasing rates below 0.15 kHz.
We present experimental results on a microwave scheme for reading out a Josephson phase qubit. A capacitively shunted superconducting quantum interference device (SQUID) is used as a nonlinear resonator which is inductively coupled to the qubit. The flux state of the qubit is detected by measuring the amplitude and phase of a microwave pulse reflected from the SQUID resonator. By this low-dissipative method, the qubit state measurement time is reduced to 25 μs, which is much faster than the conventional readout performed by switching the SQUID to its nonzero dc voltage state. The readout scheme presented here allows for reading out multiple qubits using a single microwave line by employing frequency-division multiplexing.