Millisecond coherence in a superconducting qubit

Somoroff, Aaron; Ficheux, Quentin; Mencia, Raymond; Xiong, Haonan; Kuzmin, Roman; Manucharyan, Vladimir

doi:10.48550/arxiv.2103.08578

Cited by 42 publications

(74 citation statements)

References 38 publications

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“…C ORE performance metrics of superconducting qubits have rapidly improved since their inception, with dephasing time in particular increasing four orders of magnitude from 20 nanoseconds demonstrated by Chiorescu et al [1] to hundreds of microseconds demonstrated recently [2]- [5]. To an extent, this astonishing progress in coherence time has been achieved by avoiding complexity in fabrication.…”

Section: Introductionmentioning

confidence: 99%

Qubit-compatible substrates with superconducting through-silicon vias

Grigoras,

Yurttagül,

Kaikkonen

et al. 2022

Preprint

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We fabricate and characterize superconducting through-silicon vias and electrodes suitable for superconducting quantum processors. We measure internal quality factors of a million for test resonators excited at single-photon levels, when vias are used to stitch ground planes on the front and back sides of the wafer. This resonator performance is on par with the state of the art for silicon-based planar solutions, despite the presence of vias. Via stitching of ground planes is an important enabling technology for increasing the physical size of quantum processor chips, and is a first step toward more complex quantum devices with three-dimensional integration.

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Section: Introductionmentioning

confidence: 99%

Qubit-compatible substrates with superconducting through-silicon vias

Grigoras,

Yurttagül,

Kaikkonen

et al. 2022

Preprint

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“…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

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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.

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“…This requires to operate on these systems orders of magnitude faster than the timescale set by the coupling to the environment. There is thus a continuous strive to better insulate qubits [1][2][3][4][5] and to design faster quantum operations [6][7][8][9]. Among the latter, a critical operation is the entanglement of two qubits, which requires a time lower-bounded by a speed limit t J = π/J set by a platform-dependent interaction strength J, e.g., proportional to a capacitance between two SC qubits [10].…”

Section: Introductionmentioning

confidence: 99%

Ultrafast energy exchange between two single Rydberg atoms on the nanosecond timescale

Chew,

Tomita,

Mahesh

et al. 2021

Preprint

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Rydberg atoms, with their giant electronic orbitals, exhibit dipole-dipole interaction reaching the GHz range at a distance of a micron, making them a prominent contender for realizing quantum operations well within their coherence time. However, such strong interactions have never been harnessed so far, mainly because of the stringent requirements on the fluctuation of the atom positions and the necessary excitation strength. Here, using atoms trapped in the motional groundstate of optical tweezers and excited to a Rydberg state with picosecond pulsed lasers, we observe an interaction-driven energy exchange, i.e., a Förster oscilation, occuring in a timescale of nanoseconds, two orders of magnitude faster than in any previous work with Rydberg atoms. This ultrafast coherent dynamics gives rise to a conditional phase which is the key resource for an ultrafast controlled-Z gate. This opens the path for quantum simulation and computation operating at the speed-limit set by dipole-dipole interactions with this ultrafast Rydberg platform.

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Millisecond coherence in a superconducting qubit

Cited by 42 publications

References 38 publications

Qubit-compatible substrates with superconducting through-silicon vias

Qubit-compatible substrates with superconducting through-silicon vias

Quantum crosstalk analysis for simultaneous gate operations on superconducting qubits

Ultrafast energy exchange between two single Rydberg atoms on the nanosecond timescale

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