Fast Logic with Slow Qubits: Microwave-Activated Controlled-Z Gate on Low-Frequency Fluxoniums

Ficheux, Quentin; Nguyen, Long B.; Somoroff, Aaron; Xiong, Haonan; Nesterov, Konstantin; Vavilov, Maxim; Manucharyan, Vladimir

doi:10.1103/physrevx.11.021026

Cited by 58 publications

(35 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In particular, single-qubit transition frequencies in the controlled-Z gate realization of Ref. [27], which was based on driving in proximity with the |11 − |21 transition, were only 70 and 130 MHz.…”

Section: Charge Matrix Elementsmentioning

confidence: 99%

“…A promising alternative to the transmon is the fluxonium circuit with its strongly anharmonic spectrum and long coherence time of the low-frequency transition between the ground and first excited states [24][25][26]. Microwave-activated two-qubit gates that have been implemented experimentally with fluxonium qubits are based on driving in proximity with transitions leading to higher (noncomputational) excited states of the twoqubit spectrum [27,28]. Such gate operations are facilitated by several-gigahertz transmon-like frequencies of those transitions, which results in stronger interactions between noncomputational levels in comparison to interactions between computational levels [29].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Controlled-NOT gates for fluxonium qubits via selective darkening of transitions

Nesterov¹,

Wang²,

Manucharyan³

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

We analyze the cross-resonance effect for fluxonium circuits and investigate a two-qubit gate scheme based on selective darkening of a transition. In this approach, two microwave pulses at the frequency of the target qubit are applied simultaneously with a proper ratio between their amplitudes to achieve a controlled-not operation. We study in detail coherent gate dynamics and calculate gate error. With nonunitary effects accounted for, we demonstrate that gate error below 10 −4 is possible for realistic hardware parameters. This number is facilitated by long coherence times of computational transitions and strong anharmonicity of fluxoniums, which easily prevents excitation to higher excited states during the gate microwave drive.

show abstract

Section: Charge Matrix Elementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Controlled-NOT gates for fluxonium qubits via selective darkening of transitions

Nesterov¹,

Wang²,

Manucharyan³

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…As a result, charge coupling is preferable if interaction involving higher states is desired, and flux coupling is preferable if interaction involving the computational states is intended. For example, charge coupling was used in the microwave-activated two-qubit controlledphase gate scheme involving |1 → |2 transition [57][58][59], and flux coupling resulted in strong hybridization of the lowest eigenstates in the fluxonium molecule [94]. In general, charge matrix elements are smaller than phase matrix elements due to the large inductance in the circuit (8E C > E L in Eq.…”

Section: Fluxonium Qubitmentioning

confidence: 99%

Scalable High-Performance Fluxonium Quantum Processor

Nguyen¹,

Koolstra²,

Kim³

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

“…Nonetheless, in practical implementation of quantum processors, an outstanding challenge is how to maintain or even improve gate performance with growing numbers of parallel controlled qubits [1]. For quantum processors build with superconducting qubits, isolated single-qubit gates with error rates below 0.1% [2][3][4][5] and two-qubit gates with error rates approaching 0.1% [2,[6][7][8][9][10][11][12][13] have been demonstrated in various qubit architectures [2]. However, in multi-qubit systems, implementing gate operations in parallel are commonly shown worse gate performance, especially for simultaneous two-qubit gate operations applied on nearby qubits, where gate error rates are typically increased by 0.1% − 1% [14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Quantum crosstalk analysis for simultaneous gate operations on superconducting qubits

Zhao¹,

Linghu²,

Li³

et al. 2021

Preprint

View full text Add to dashboard Cite

Maintaining or even improving gate performance with growing numbers of parallel controlled qubits is a vital requirement towards fault-tolerant quantum computing. For superconducting quantum processors, though isolated one-or two-qubit gates have been demonstrated with high-fidelity, implementing these gates in parallel commonly show worse performance. Generally, this degradation is attributed to various crosstalks between qubits, such as quantum crosstalk due to residual inter-qubit coupling. An understanding of the exact nature of these crosstalks is critical to figuring out respective mitigation schemes and improved qubit architecture designs with low crosstalk. Here we give a theoretical analysis of quantum crosstalk impact on simultaneous gate operations in a qubit architecture, where fixed-frequency transmon qubits are coupled via a tunable bus, and sub-100-ns controlled-Z (CZ) gates can be realized by applying a baseband flux pulse on the bus. Our analysis shows that for microwave-driven single qubit gates, the dressing from qubit-qubit coupling can cause nonnegligible cross-driving errors when qubits operate near frequency collision regions. During CZ gate operations, although unwanted near-neighbor interactions are nominally turned off, sub-MHz parasitic next-near-neighbor interactions involving spectator qubits can still exist, causing considerable leakage or control error when one operates qubit systems around these parasitic resonance points. To ensure high-fidelity simultaneous operations, this could rise a request to figure out a better way to balance the gate error from target qubit systems themselves and the error from non-participating spectator qubits. Overall, our analysis suggests that towards useful quantum processors, the qubit architecture should be examined carefully in the context of high-fidelity simultaneous gate operations in a scalable qubit lattice.

show abstract

Fast Logic with Slow Qubits: Microwave-Activated Controlled-Z Gate on Low-Frequency Fluxoniums

Cited by 58 publications

References 64 publications

Controlled-NOT gates for fluxonium qubits via selective darkening of transitions

Controlled-NOT gates for fluxonium qubits via selective darkening of transitions

Scalable High-Performance Fluxonium Quantum Processor

Quantum crosstalk analysis for simultaneous gate operations on superconducting qubits

Contact Info

Product

Resources

About