Fluxon-based quantum simulation in circuit QED

Petrescu, Alexandru; Türeci, Hakan E.; Ustinov, A. V.; Pop, I.

doi:10.1103/physrevb.98.174505

Cited by 15 publications

(10 citation statements)

References 92 publications

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“…We extract QP relaxation times in the range of 1 s and we observe QP bursts every ∼20 s. The current level of coherence of grAl resonators makes them attractive for integration in quantum devices, while it also evidences the need to reduce the density of nonequilibrium QPs. DOI: 10.1103/PhysRevLett.121.117001 Superconducting materials with a high kinetic inductance play a prominent role in superconducting circuits, such as quantum bits (qubits) with remarkably high energy relaxation times [1][2][3][4], topological [5,6] and protected qubits [7][8][9], coherent quantum phase slip circuits [10][11][12][13], wideband parametric amplifiers [14,15], and resonators for quantum state of light engineering [16,17]. As the kinetic inductance fraction α ¼ L kinetic =L total increases, so does the susceptibility of superconducting circuits to quasiparticle (QP) excitations, which constitutes an asset for kinetic inductance detectors (KIDs) [18].…”

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confidence: 99%

Loss Mechanisms and Quasiparticle Dynamics in Superconducting Microwave Resonators Made of Thin-Film Granular Aluminum

et al. 2018

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Superconducting high kinetic inductance elements constitute a valuable resource for quantum circuit design and millimeter-wave detection. Granular aluminum (grAl) in the superconducting regime is a particularly interesting material since it has already shown a kinetic inductance in the range of nH/□ and its deposition is compatible with conventional Al/AlOx/Al Josephson junction fabrication. We characterize microwave resonators fabricated from grAl with a room temperature resistivity of 4×10^{3} μΩ cm, which is a factor of 3 below the superconductor to insulator transition, showing a kinetic inductance fraction close to unity. The measured internal quality factors are on the order of Q_{i}=10^{5} in the single photon regime, and we demonstrate that nonequilibrium quasiparticles (QPs) constitute the dominant loss mechanism. We extract QP relaxation times in the range of 1 s and we observe QP bursts every ∼20 s. The current level of coherence of grAl resonators makes them attractive for integration in quantum devices, while it also evidences the need to reduce the density of nonequilibrium QPs.

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Loss Mechanisms and Quasiparticle Dynamics in Superconducting Microwave Resonators Made of Thin-Film Granular Aluminum

et al. 2018

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“…Future work will concentrate on extending the gate operation to a universal set of single-qubit gates. Finally, we note that qubits with a similar level structure to that of the 0-π qubit might leverage related ideas [36,[54][55][56][57][58][59].…”

Section: Resultsmentioning

confidence: 95%

Control and coherence time enhancement of the 0–π qubit

Paolo¹,

Grimsmo

Groszkowski

et al. 2019

New J. Phys.

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Kitaev's 0-π qubit encodes quantum information in two protected, near-degenerate states of a superconducting quantum circuit. In a recent work, we have shown that the coherence times of a realistic 0-π device can surpass that of today's best superconducting qubits (Groszkowski et al 2018 New J. Phys. 20 043053). Here we address controllability of the 0-π qubit. Specifically, we investigate the potential for dispersive control and readout, and introduce a new, fast and high-fidelity singlequbit gate that can interpolate smoothly between logical X and Z. We characterize the action of this gate using a multi-level treatment of the device, and analyze the impact of circuit-element disorder and deviations in control and circuit parameters from their optimal values. Furthermore, we propose a cooling scheme to decrease the photon shot-noise dephasing rate, which we previously found to limit the coherence times of 0-π devices within reach of current experiments. Using this approach, we predict coherence time enhancements between one and three orders of magnitude, depending on parameter regime. ζ-mode) [22]. Nevertheless, we found that the 0-π qubit still has the potential to outperform state-of-the-art superconducting devices. Below, we propose a method to further enhance the coherence time by orders of magnitude by cooling the ζ-mode.However, as can be expected, the price of intrinsic noise protection in the 0-π qubit is that it is difficult to perform logical operations on this device. In particular, protection from noise comes in part from the exponentially small overlap of its logical wave functions. As a result, matrix elements of local operators between the two logical states will also be small, thus resulting in extremely slow gates. In [20], Brooks et al proposed a universal set of protected logical operations based on coupling to an ultra-high impedance LC oscillator. However, these operations were based on an idealized model of the qubit and with parameters that are difficult to realize in practice. Further work is required to determine the potential of this approach in a more realistic setting.Motivated by the prospect of realizing 0-π qubits in the near term, we investigate alternative approaches to measurement and control with lower experimental complexity. The operations we propose are not protected in the same sense as those proposed in [20], because they rely either on operating the device in a regime where the qubit is not fully isolated from the environment, or they make use of excited states outside the qubit manifold. In particular, we develop a single-qubit gate based on a multi-level excursion through higher energy levels. Nevertheless, we hope that these schemes will be useful for both characterization and control of 0-π qubits in near-to-medium-term experiments.This work is organized as follows. In section 2, we introduce the 0-π qubit and provide a simplified effective model for the 0-π circuit with only a single degree of freedom. In section 3, we discuss general coupling strategies for qubit co...

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“…Recently, some coherent quantum-mechanical effects in the dynamics of MFs trapped in the JJPAs with high kinetic inductances were theoretically studied in Ref. [19].…”

Section: Introductionmentioning

confidence: 99%

Quantum dynamics of a single fluxon in Josephson junctions parallel arrays with large kinetic inductances

Seidov,

Fistul

2021

Preprint

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Fluxon-based quantum simulation in circuit QED

Cited by 15 publications

References 92 publications

Loss Mechanisms and Quasiparticle Dynamics in Superconducting Microwave Resonators Made of Thin-Film Granular Aluminum

Loss Mechanisms and Quasiparticle Dynamics in Superconducting Microwave Resonators Made of Thin-Film Granular Aluminum

Control and coherence time enhancement of the 0–π qubit

Quantum dynamics of a single fluxon in Josephson junctions parallel arrays with large kinetic inductances

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