Bogoliubov quasiparticles in superconducting qubits

Glazman, L. I.; Catelani, Gianluigi

doi:10.21468/scipostphyslectnotes.31

Cited by 51 publications

(33 citation statements)

References 50 publications

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“…A detailed review of quasiparticle effects in superconducting qubits in various circuit topologies has recently been published by Leonid Glazman and Gianluigi Catelani. 30 A simple circuit model for a JJ treats this element as a generalized complex admittance that is frequency-dependent and phase-dependent (Fig. 6a).…”

Section: [H3] Qubit Measurementsmentioning

confidence: 99%

“…27,28 Moreover, although operation at millikelvin temperatures should freeze out electronic and vibrational degrees of freedom, a substantial population of nonequilibrium excitations 29 is observed, constituting a significant source of decoherence. 11,30 In this Review, the main sources of materials-related decoherence observed in superconducting qubits of varying degrees of circuit complexity are introduced, along with our current understanding of the microscopic physics underlying these noise sources. We start by describing the circuits that form the basis of conventional Josephson tunnel junction qubits and listing their suspected sources of imperfection.…”

Section: [H1] Introductionmentioning

confidence: 99%

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Engineering high-coherence superconducting qubits

Siddiqi

2021

Nat Rev Mater

170

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Advances in materials science and engineering have played a central role in the development of classical computers, and will undoubtedly be critical in propelling the maturation of quantum information technologies. In approaches to quantum computation based on superconducting circuits, as one goes from bulk materials to functional devices, amorphous insulating films and nonequilibrium excitations-electronic and phononic-are introduced, leading to dissipation and fluctuations that limit the computational power of state-of-the-art qubits and processors. In this Review, the major sources of decoherence in superconducting qubits are identified through an exploration of seminal qubit and resonator experiments. The proposed microscopic mechanisms associated with these imperfections are summarized, and directions for future research are discussed. The trade-offs between simple qubit primitives based on a single Josephson tunnel junction and more complex designs that use additional circuit elements, or new junction modalities, to reduce sensitivity to local noise sources are discussed, particularly in the context of materials optimization strategies for each architecture.

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Section: [H3] Qubit Measurementsmentioning

confidence: 99%

Section: [H1] Introductionmentioning

confidence: 99%

Engineering high-coherence superconducting qubits

Siddiqi

2021

Nat Rev Mater

170

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“…Strong parity polarization may not be surprising for a system in thermal equilibrium at temperatures below 100 mK, typical of these experiments, corresponding to a thermal energy small compared to the singlet-doublet energy difference away from the transition. However, parity lifetimes in Josephson junctions are seldom determined by thermal fluctuations, but rather by highly energetic non-equilibrium quasiparticles often observed in superconducting circuits [82]. While non-equilibrium quasiparticles are most likely also present in our device, we believe that their influence is suppressed by the large charging energy of the quantum dot junction.…”

Section: Dynamics Of the Singlet-doublet Transitionmentioning

confidence: 87%

Singlet-doublet transitions of a quantum dot Josephson junction detected in a transmon circuit

Bargerbos,

Pita-Vidal,

Žitko

et al. 2022

Preprint

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We realize a hybrid superconductor-semiconductor transmon device in which the Josephson effect is controlled by a gate-defined quantum dot in an InAs/Al nanowire. Microwave spectroscopy of the transmon's transition spectrum allows us to probe the ground state parity of the quantum dot as a function of gate voltages, external magnetic flux, and magnetic field applied parallel to the nanowire. The measured parity phase diagram is in agreement with that predicted by a singleimpurity Anderson model with superconducting leads. Through continuous time monitoring of the circuit we furthermore resolve the quasiparticle dynamics of the quantum dot Josephson junction across the phase boundaries. Our results can facilitate the realization of semiconductor-based 0 − π qubits and Andreev qubits.

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“…A future goal is to achieve greater T 1 in order to have more reliable qubits, but this is experimentally challenging. Relaxation can be driven by many loss channels, such as radiation losses [15], dielectric losses [16], two-level fluctuators in the junction materials [17] and by the excess of quasiparticles in the superconducting materials [18][19][20]. The relaxation rate depends on every of these loss channel affecting the qubit [38].…”

Section: Limits Set By Csl In Superconducting Quantum Computersmentioning

confidence: 99%

Fundamental limits of superconducting quantum computers

Vischi¹,

Ferialdi²,

Trombettoni³

et al. 2022

Preprint

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The Continuous Spontaneous Localization (CSL) model is an alternative formulation of quantum mechanics which introduces a noise coupled non linearly to the wave function to account for its collapse. We consider CSL effects on quantum computers made of superconducting transmon qubits. As a direct effect CSL reduces quantum superpositions of the computational basis states of the qubits: we show the reduction rate to be negligibly small. However, an indirect effect of CSL, dissipation induced by the noise, also leads transmon qubits to decohere, by generating additional quasiparticles. Since the decoherence rate of transmon qubits depends on the quasiparticle density, by computing their generation rate induced by CSL, we can estimate the corresponding quasiparticle density and thus the limit set by CSL on the performances of transmon quantum computers. We show that CSL could spoil the quantum computation of practical algorithms on large devices. We further explore the possibility of testing CSL effects on superconducting devices.

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Bogoliubov quasiparticles in superconducting qubits

Cited by 51 publications

References 50 publications

Engineering high-coherence superconducting qubits

Engineering high-coherence superconducting qubits

Singlet-doublet transitions of a quantum dot Josephson junction detected in a transmon circuit

Fundamental limits of superconducting quantum computers

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