Dynamics of a qubit coupled to a broadened harmonic mode at finite detuning

Nesi, Francesco; Grifoni, Milena; Paladino, E.

doi:10.1088/1367-2630/9/9/316

Cited by 25 publications

(61 citation statements)

References 28 publications

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“…For unbiased qubits, we can compare our predictions with the analytical results obtained in [31] by starting from a spin-boson model with the effective spectral density (10). In [31], a socalled weak damping approximation (WDA) based on the NIBA is applied.…”

Section: The Unbiased Qubitmentioning

confidence: 99%

“…In [31], a socalled weak damping approximation (WDA) based on the NIBA is applied. The WDA allows a non-perturbative treatment of the coupling between the TLS and HO and hence can reproduce the occurrence of two dominating frequencies as expected e.g.…”

Section: The Unbiased Qubitmentioning

confidence: 99%

“…However, it has been shown that for strong qubit-HO coupling g and for small detuning δ = − b , where b is the qubit energy splitting, such an approximation breaks down [27], as coherent exchange processes between the TLS and the oscillator are disregarded. For an unbiased qubit, the non-interacting blip approximation (NIBA) used in [28]- [31] circumvents this problem as it is non-perturbative in the coupling g and therefore takes correctly into account the influence of the oscillator on the TLS. Moreover, it allows an analytic treatment of the dynamics.…”

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confidence: 99%

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Dissipative dynamics of a biased qubit coupled to a harmonic oscillator: analytical results beyond the rotating wave approximation

Hausinger¹,

Grifoni

2008

New J. Phys.

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We study the dissipative dynamics of a biased two-level system (TLS) coupled to a harmonic oscillator (HO), the latter interacting with an Ohmic environment. Using Van-Vleck perturbation theory and going to second order in the coupling between TLS and HO, we show how the Hamiltonian of the TLS-HO system can be diagonalized analytically. Our model represents an improvement to the usually used Jaynes-Cummings Hamiltonian as an initial rotating wave approximation is avoided. By assuming a weak coupling to the thermal bath, analytical expressions for the time evolution of the populations of the TLS are found: the population is characterized by a multiplicity of damped oscillations together with a complex relaxation dynamics towards thermal equilibrium. The long time evolution is characterized by a single relaxation rate, which is largest at resonance and whose expression can be given in closed analytic form.

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Section: The Unbiased Qubitmentioning

confidence: 99%

Section: The Unbiased Qubitmentioning

confidence: 99%

mentioning

confidence: 99%

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Dissipative dynamics of a biased qubit coupled to a harmonic oscillator: analytical results beyond the rotating wave approximation

Hausinger¹,

Grifoni

2008

New J. Phys.

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“…Simultaneously, the bath causes coherence decay and, for low temperature, a relaxation from the state |↑, 1 to |↑, 0 occurs. We emphasize here that there is no transition |↑, 0 → |↓, 0 since the qubit experiences an effective heat bath with a spectral density sharply peaked at the oscillator frequency Ω [26,27,28,29]. Thus, for large times t ≫ Ω/v, the spectral density at the qubit splitting vt vanishes and, consequently, the 3 qubit is effectively decoupled from the bath.…”

Section: Entanglement Creationmentioning

confidence: 97%

Entanglement and disentanglement in circuit QED architectures

Zueco¹,

Reuther²,

Hänggi³

et al. 2010

Physica E: Low-dimensional Systems and Nanostructures

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We propose a protocol for creating entanglement within a dissipative circuit QED network architecture that consists of two electromagnetic circuits (cavities) and two superconducting qubits. The system interacts with a quantum environment, giving rise to decoherence and dissipation. We discuss the preparation of two separate entangled cavityqubit states via Landau-Zener sweeps, after which the cavities interact via a tunable "quantum switch" which is realized with an ancilla qubit. Moreover, we discuss the decay of the resulting entangled two-cavity state due to the influence of the environment, where we focus on the entanglement decay.

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“…The peaks of the spectral density correspond to longtime correlations of the quantum noise that may lead to non-Markov effects. Therefore, a treatment with a fully Markovian master equation is not appropriate [17]. We thus employ ideas that have been used for studying decoherence due to 1/f noise [33][34][35][36][37].…”

Section: B Driven Oscillator As Effective Bathmentioning

confidence: 99%

Non-Markovian qubit decoherence during dispersive readout

2012

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We study qubit decoherence under generalized dispersive readout, i.e., we investigate a qubit coupled to a resonantly driven dissipative harmonic oscillator. We provide a complete picture by allowing for arbitrarily large qubit-oscillator detuning and by considering also a coupling to the square of the oscillator coordinate, which is relevant for flux qubits. Analytical results for the decoherence time are obtained by a transformation of the qubit-oscillator Hamiltonian to the dispersive frame and a subsequent master equation treatment beyond the Markov limit. We predict a crossover from Markovian decay to a decay with Gaussian shape. Our results are corroborated by the numerical solution of the full qubit-oscillator master equation in the original frame.

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Dynamics of a qubit coupled to a broadened harmonic mode at finite detuning

Cited by 25 publications

References 28 publications

Dissipative dynamics of a biased qubit coupled to a harmonic oscillator: analytical results beyond the rotating wave approximation

Dissipative dynamics of a biased qubit coupled to a harmonic oscillator: analytical results beyond the rotating wave approximation

Entanglement and disentanglement in circuit QED architectures

Non-Markovian qubit decoherence during dispersive readout

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