Stoquasticity in circuit QED

• URL: http://arxiv.org/abs/2011.01109v3
• Date: Mon, 29 Mar 2021 07:24:26 GMT
• Title: Stoquasticity in circuit QED
• Authors: Alessandro Ciani and Barbara M. Terhal
• Abstract summary: We show that scalable sign-problem free path integral Monte Carlo simulations can typically be performed for such systems. We corroborate the recent finding that an effective, non-stoquastic qubit Hamiltonian can emerge in a system of capacitively coupled flux qubits.
• Score: 78.980148137396
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We analyze whether circuit-QED Hamiltonians are stoquastic focusing on systems of coupled flux qubits: we show that scalable sign-problem free path integral Monte Carlo simulations can typically be performed for such systems. Despite this, we corroborate the recent finding [arXiv:1903.06139] that an effective, non-stoquastic qubit Hamiltonian can emerge in a system of capacitively coupled flux qubits. We find that if the capacitive coupling is sufficiently small, this non-stoquasticity of the effective qubit Hamiltonian can be avoided if we perform a canonical transformation prior to projecting onto an effective qubit Hamiltonian. Our results shed light on the power of circuit-QED Hamiltonians for the use of quantum adiabatic computation and the subtlety of finding a representation which cures the sign problem in these systems

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