Spin-boson quantum phase transition in multilevel superconducting qubits
- URL: http://arxiv.org/abs/2010.01016v2
- Date: Fri, 17 Dec 2021 13:45:44 GMT
- Title: Spin-boson quantum phase transition in multilevel superconducting qubits
- Authors: Kuljeet Kaur, Th\'eo S\'epulcre, Nicolas Roch, Izak Snyman, Serge
Florens and Soumya Bera
- Abstract summary: We show that the intrinsic multilevel structure of superconducting qubits drastically restricts the validity of the spin-boson paradigm due to phase localization.
Imposing charge discreteness in a simple variational state accounts for these multilevel effects, that are relevant for a large class of devices.
- Score: 3.952191799203902
- License: http://creativecommons.org/licenses/by/4.0/
- Abstract: Superconducting circuits are currently developed as a versatile platform for
the exploration of many-body physics, by building on non-linear elements that
are often idealized as two-level qubits. A classic example is given by a charge
qubit that is capacitively coupled to a transmission line, which leads to the
celebrated spin-boson description of quantum dissipation. We show that the
intrinsic multilevel structure of superconducting qubits drastically restricts
the validity of the spin-boson paradigm due to phase localization, which
spreads the wavefunction over many charge states. Numerical Renormalization
Group simulations also show that the quantum critical point moves out of the
physically accessible range in the multilevel regime. Imposing charge
discreteness in a simple variational state accounts for these multilevel
effects, that are relevant for a large class of devices.
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