Circuit QED: superconducting qubits coupled to microwave photons

Girvin, S. M.; Schoelkopf, Robert

doi:10.1093/acprof:oso/9780199681181.003.0003

Cited by 85 publications

(115 citation statements)

References 232 publications

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“…Refs. [34][35][36][37][38][39][40][41][42][43], this work specifically aims to introduce new quantum engineers (academic and industrial alike) to the terminology and state-of-the-art practices used in the rapidly accelerating field of superconducting quantum computing. The reader is assumed to be familiar with basic concepts that span classical physics, quantum mechanics, and electrical engineering.…”

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confidence: 99%

A quantum engineer's guide to superconducting qubits

Krantz

Kjærgaard

Yan

et al. 2019

Applied Physics Reviews

1,401

962

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The aim of this review is to provide quantum engineers with an introductory guide to the central concepts and challenges in the rapidly accelerating field of superconducting quantum circuits. Over the past twenty years, the field has matured from a predominantly basic research endeavor to one that increasingly explores the engineering of larger-scale superconducting quantum systems. Here, we review several foundational elements -qubit design, noise properties, qubit control, and readout techniques -developed during this period, bridging fundamental concepts in circuit quantum electrodynamics (cQED) and contemporary, stateof-the-art applications in gate-model quantum computation.

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mentioning

confidence: 99%

A quantum engineer's guide to superconducting qubits

Krantz

Kjærgaard

Yan

et al. 2019

Applied Physics Reviews

1,401

962

View full text Add to dashboard Cite

show abstract

“…The coupling is now characterized by the spontaneous emission rate Γ. On one hand (for a large but finite L) Fermi's golden rule gives Γ = 2πg 2 ρ [34]. On the other hand, correspondence principle requires that the excited state lifetime T 1 ≡ 1/2πΓ is given by a classical expression T 1 = Z ∞ C J (the "RC" charge relaxation time).…”

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confidence: 99%

Superstrong coupling in circuit quantum electrodynamics

et al. 2019

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Vacuum fluctuations fundamentally affect an atom by inducing a finite excited state lifetime along with a Lamb shift of its transition frequency. Here we report the reverse effect: modification of vacuum modes by a single atom in circuit quantum electrodynamics. Our one-dimensional vacuum is a long section of a high wave impedance (comparable to resistance quantum) superconducting transmission line. It is directly wired to a transmon qubit circuit. Owing to the combination of high impedance and galvanic connection, the transmon's spontaneous emission linewidth can greatly exceed the discrete transmission line modes spacing. This condition defines a previously unexplored superstrong coupling regime of quantum electrodynamics where many frequency-resolved vacuum modes hybridize with a single atom. We establish this regime by observing the spontaneous emission line of the transmon, revealed through the mode-by-mode measurement of the vacuum's density of states. The linewidth as well as the atom-induced dispersive photon-photon interaction are accurately described by a physically transparent Caldeira-Leggett model, with the transmon's quartic non-linearity treated as a perturbation. Non-perturbative modification of vacuum, including inelastic scattering of single photons, can be enabled by the superstrong coupling regime upon replacing the transmon by more anharmonic qubits, with broad implications for simulating quantum impurity models of many-body physics.arXiv:1809.10739v2 [cond-mat.supr-con]

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“…Within this weak coupling assumption, we can obtain the normal modes of the transmission line; we will take open circuit boundary conditions [39]. We can write the flux φ(x,t) in terms of normal modes as where the mode frequencies are given by ω n = πn/( √ cL) and we defined the coupling capacitances to the nth mode…”

Section: Appendix B: Transmon Coupled To a Transmission Line Resonatormentioning

confidence: 99%

Three-qubit direct dispersive parity measurement with tunable coupling qubits

Ciani

DiVincenzo

2017

Phys. Rev. B

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We consider the direct three-qubit parity measurement scheme with two measurement resonators, using circuit quantum electrodynamics to analyze its functioning for several different types of superconducting qubits. We find that for the most common, transmon-like qubit, the presence of additional qubit-state-dependent coupling terms of the two resonators hinders the possibility of performing the direct parity measurement. We show how this problem can be solved by employing the tunable coupling qubit (TCQ) in a particular designed configuration. In this case, we effectively engineer the original model Hamiltonian by canceling the harmful terms. We further develop an analysis of the measurement in terms of information gains and provide some estimates of the typical parameters for optimal operation with TCQs.

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Circuit QED: superconducting qubits coupled to microwave photons

Abstract: These lecture notes discuss the quantum electrodynamics of superconducting circuits.

Cited by 85 publications

References 232 publications

A quantum engineer's guide to superconducting qubits

A quantum engineer's guide to superconducting qubits

Superstrong coupling in circuit quantum electrodynamics

Three-qubit direct dispersive parity measurement with tunable coupling qubits

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