Balanced cross-Kerr coupling for superconducting qubit readout

• URL: http://arxiv.org/abs/2501.09010v1
• Date: Wed, 15 Jan 2025 18:52:08 GMT
• Title: Balanced cross-Kerr coupling for superconducting qubit readout
• Authors: Alex A. Chapple, Othmane Benhayoune-Khadraoui, Simon Richer, Alexandre Blais,
• Abstract summary: Dispersive readout, the standard method for measuring superconducting qubits, is limited by multiphoton qubit-resonator processes. In this work, we propose a novel readout method, termed "junction readout"
• Score: 41.94295877935867
• License:
• Abstract: Dispersive readout, the standard method for measuring superconducting qubits, is limited by multiphoton qubit-resonator processes arising even at moderate drive powers. These processes degrade performance, causing dispersive readout to lag behind single- and two-qubit gates in both speed and fidelity. In this work, we propose a novel readout method, termed "junction readout". Junction readout leverages the nonperturbative cross-Kerr interaction resulting from coupling a qubit and a resonator via a Josephson junction. Furthermore, by adding a capacitive coupling in parallel to the junction, Purcell decay can be suppressed without the need for a Purcell filter. We also show that junction readout is more robust against deleterious multiphoton processes, and offers greater flexibility for resonator frequency allocation. Crucially, junction readout achieves superior performance compared to dispersive readout while maintaining similar hardware overhead. Numerical simulations show that junction readout can achieve fidelities exceeding $99.99\%$ in under $30$ ns, making it a promising alternative for superconducting qubit readout with current hardware.

Related papers

• Impact of Josephson junction array modes on fluxonium readout [0.0]
  We theoretically analyze measurement-induced state transitions (MIST) during the dispersive readout of a fluxonium qubit. We show that these new kinds of MIST processes can be relevant when using realistic circuit parameters and relatively low readout drive powers.
  arXiv  Detail & Related papers  (2024-12-19T12:28:46Z)
• Robustness of longitudinal transmon readout to ionization [79.16635054977068]
  Multi-photon processes deteriorate the quantum non-demolition character of the dispersive readout in circuit QED. Alternative methods such as the longitudinal readout have been proposed. We show that fast, high-fidelity QND readout of transmon qubits is possible with longitudinal coupling.
  arXiv  Detail & Related papers  (2024-12-10T18:32:30Z)
• Fast multiplexed superconducting qubit readout with intrinsic Purcell filtering [2.0628957149004683]
  In superconducting quantum circuits, fast qubit measurement has been achieved using a dispersively coupled resonator with a large external linewidth. This necessitates the use of a Purcell filter that protects the qubit from relaxation through the readout channel. Here we show that a readout resonator and filter resonator, coupled to each other both capacitively and inductively, can produce a compact notch-filter circuit.
  arXiv  Detail & Related papers  (2024-09-08T04:06:53Z)
• Ultrafast Superconducting Qubit Readout with the Quarton Coupler [1.4571671739637337]
  State-of-the-art readout is based on a dispersive cross-Kerr coupling between a qubit and its readout resonator. We present a new scheme that uses the quarton coupler to facilitate a large (greater than 250 MHz) cross-Kerr between a transmon qubit and its readout resonator. Full master equation simulations show a 5 ns readout time with greater than 99% readout and QND fidelity.
  arXiv  Detail & Related papers  (2024-02-24T00:39:35Z)
• Enhancing Dispersive Readout of Superconducting Qubits Through Dynamic Control of the Dispersive Shift: Experiment and Theory [47.00474212574662]
  A superconducting qubit is coupled to a large-bandwidth readout resonator. We show a beyond-state-of-the-art two-state-readout error of only 0.25,%$ in 100 ns integration time. The presented results are expected to further boost the performance of new and existing algorithms and protocols.
  arXiv  Detail & Related papers  (2023-07-15T10:30:10Z)
• Broadband Bandpass Purcell Filter for Circuit Quantum Electrodynamics [5.250183242080687]
  In circuit quantum electrodynamics (QED), qubits are typically measured using dispersively-coupled readout resonators. Inserting a Purcell filter counters this effect while maintaining high readout fidelity, but reduces measurement bandwidth and thus limits multiplexing readout capacity. We develop and implement a multi-stage bandpass Purcell filter that yields better qubit protection while simultaneously increasing measurement bandwidth and multiplexed capacity.
  arXiv  Detail & Related papers  (2023-06-09T21:10:32Z)
• Qubit readouts enabled by qubit cloaking [49.1574468325115]
  Time-dependent drives play a crucial role in quantum computing efforts. They enable single-qubit control, entangling logical operations, as well as qubit readout. Qubit cloaking was introduced in Lled'o, Dassonneville, et al.
  arXiv  Detail & Related papers  (2023-05-01T15:58:25Z)
• Superconducting coupler with exponentially large on-off ratio [68.8204255655161]
  Tunable two-qubit couplers offer an avenue to mitigate errors in multiqubit superconducting quantum processors. Most couplers operate in a narrow frequency band and target specific couplings, such as the spurious $ZZ$ interaction. We introduce a superconducting coupler that alleviates these limitations by suppressing all two-qubit interactions with an exponentially large on-off ratio.
  arXiv  Detail & Related papers  (2021-07-21T03:03:13Z)
• Coherent superconducting qubits from a subtractive junction fabrication process [48.7576911714538]
  Josephson tunnel junctions are the centerpiece of almost any superconducting electronic circuit, including qubits. In recent years, sub-micron scale overlap junctions have started to attract attention. This work paves the way towards a more standardized process flow with advanced materials and growth processes, and constitutes an important step for large scale fabrication of superconducting quantum circuits.
  arXiv  Detail & Related papers  (2020-06-30T14:52:14Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.