High-Contrast 
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 Interaction Using Superconducting Qubits with Opposite-Sign Anharmonicity

Zhao, Peng; Xu, Peng; Lan, Dong; Chu, Ji; Tan, Xinsheng; Yu, Haifeng; Yu, Yang

doi:10.1103/physrevlett.125.200503

Cited by 73 publications

(52 citation statements)

References 38 publications

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“…The Hamiltonian interaction term is written as ζσ z1 σ z2 , acting on the two qubits. Typically, in superconducting systems, it arises from the interaction of the |11 state with the non-computational state in the physical qubits, and can both be used as a resource for entangling gates [21][22][23][24] or viewed as cross-talk noise that needs to be suppressed [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41].…”

Section: Physical Applicationsmentioning

confidence: 99%

“…The second approach is to choose a hybrid qubit system with opposite anharmonicity, which allows parameter engineering to suppress the ZZ interaction. One implementation is using a transmon and a capacitively shunt flux qubit (CSFQ) [25,26]. Other methods include using additional off-resonant drive [39][40][41] and different types of qubits have also been proposed [38].…”

Section: B Zz Coupling Suppression In the Quasi-dispersive Regimementioning

confidence: 99%

“…(36) in the strong dispersive regime, up to O( 1 ∆ 3 j ). The expression has also been computed using diagrammatic techniques within the strong dispersive regime [25,50]. A more general expression, including an additional direct coupling between the qubits and an anharmonicity in the resonator, is derived in [37].…”

Section: B Zz Coupling Suppression In the Quasi-dispersive Regimementioning

confidence: 99%

“…In the first regime, where the leakagelevel-mediated ZZ interaction can be used to generate CZ gates [21][22][23][24], we consider the two-excitation manifold and compute accurate approximations of the ZZ interaction strength applicable to the full parameter regime for gate implementation. In the second scenario, we study the suppression of ZZ interactions [10,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] in the traditional setup of resonator mediated coupling without direct qubit-qubit interaction. We compute the perturbative expansion of the ZZ interaction up to the 8th order perturbation as parametric expressions.…”

mentioning

confidence: 99%

“…3. (a):Interaction and energy level diagram of the twoexcitation manifold in the unperturbed Hamiltonian given by Eq (25)…”

mentioning

confidence: 99%

See 4 more Smart Citations

Non-perturbative analytical diagonalization of Hamiltonians with application to coupling suppression and enhancement in cQED

Li,

Calarco,

Motzoi

2021

Preprint

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Deriving effective Hamiltonian models plays an essential role in quantum theory, with particular emphasis in recent years on control and engineering problems. In this work, we present two symbolic methods for computing effective Hamiltonian models: the Non-perturbative Analytical Diagonalization (NPAD) and the Recursive Schrieffer-Wolff Transformation (RSWT). NPAD makes use of the Jacobi iteration and works without the assumptions of perturbation theory while retaining convergence, allowing to treat a very wide range of models. In the perturbation regime, it reduces to RSWT, which takes advantage of an in-built recursive structure where remarkably the number of terms increases only linearly with perturbation order, exponentially decreasing the number of terms compared to the ubiquitous Schrieffer-Wolff method. Both methods consist of elementary algebra and can be easily automated to obtain closed-form expressions. To demonstrate the application of the methods, we study the ZZ interaction of superconducting qubits systems in two different parameter regimes. In the near-resonant regime, the method produces an analytical expression for the effective ZZ interaction strength, with an improvement of at least one order of magnitude compared to neglecting the comparably further detuned state. In the dispersive regime, we calculate perturbative corrections up to the 8th order and accurately identify a regime where ZZ interaction is suppressed in a simple model with only resonator-mediated coupling.

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Section: Physical Applicationsmentioning

confidence: 99%

Section: B Zz Coupling Suppression In the Quasi-dispersive Regimementioning

confidence: 99%

Section: B Zz Coupling Suppression In the Quasi-dispersive Regimementioning

confidence: 99%

mentioning

confidence: 99%

“…3. (a):Interaction and energy level diagram of the twoexcitation manifold in the unperturbed Hamiltonian given by Eq (25)…”

mentioning

confidence: 99%

See 3 more Smart Citations

Non-perturbative analytical diagonalization of Hamiltonians with application to coupling suppression and enhancement in cQED

Li,

Calarco,

Motzoi

2021

Preprint

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Simulation of Two‐Qubit Gates with a Superconducting Qudit

Dong

Liu

Wang

et al. 2021

Physica Status Solidi (b)

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Herein, a two‐qubit system is experimentally simulated through a four‐level superconducting circuit. By mapping the energy levels of the two‐qubit system to a noncomposite system, some two‐qubit gates with designed microwave pulses, such as Hadamard and CNOT gates, are implemented. Furthermore, the Shannon entropy of the simulated two‐qubit system is measured and the log 2 uncertainty relation is verified, which describes that the noncomposite single‐qudit system possesses hidden quantum correlations.

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Phase Calibration of the Parametric Gate in the Superconducting Circuits

Liu

Guan

Liu

et al. 2022

Physica Status Solidi (b)

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The quantum gate, as the foundation of quantum computation, depends on the architecture of the quantum chip, especially in superconducting systems. The parametric modulation to the flux bias is an important protocol to realize the multi‐qubit gate, which has some intrinsic advantages. Similar to other two‐qubit operations, parametric gates leave the extra phase in single‐qubit space, which is required to be corrected. In this article, the relation between the phases of the modulated pulse and the applied microwaves is experimentally characterized. By adjusting the envelope shape and phase of the applied pulses, the extra phase of the one qubit generated by the two‐qubit gate is suppressed via a simple and fast Ramsey‐like experiment. The tomography results demonstrate that this protocol is an effective calibrating method for future large‐scale quantum circuit manipulation.

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High-Contrast ZZ Interaction Using Superconducting Qubits with Opposite-Sign Anharmonicity

Cited by 73 publications

References 38 publications

Non-perturbative analytical diagonalization of Hamiltonians with application to coupling suppression and enhancement in cQED

Non-perturbative analytical diagonalization of Hamiltonians with application to coupling suppression and enhancement in cQED

Simulation of Two‐Qubit Gates with a Superconducting Qudit

Phase Calibration of the Parametric Gate in the Superconducting Circuits

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