Hybrid Two-Qubit Gate using Circuit QED System with Triple-Leg Stripline Resonator

TL;DR

This paper proposes a novel circuit QED system with a triple-leg stripline resonator that enables reliable two-qubit gate operations, combining superconducting and flying microwave qubits, with potential for scalable quantum computing.

Contribution

It introduces a new hybrid circuit QED system with degenerate modes, enabling controlled quantum gate operations between different types of qubits.

Findings

The system supports a reliable controlled phase flip gate.

Theoretical demonstration aligns with experimentally feasible parameters.

Mode degeneracy enables selective qubit coupling.

Abstract

We theoretically propose a circuit QED system implemented with triple-leg stripline resonator (TSR). Unlikely from linear stripline resonator, the fundamental intra-cavity microwave modes of the TSR are two-fold degenerate. When a superconducting qubit is placed near one of the TSR legs, one fundamental mode is directly coupled to the qubit, while the other one remains uncoupled. Our system closely resembles an optical cavity QED system, where an atom in a cavity couples only to the incident photon with a specific polarization by placing a polarization beamsplitter in front of the optical cavity. Using our circuit QED system, we have theoretically studied a two-qubit quantum gate operation in a hybrid qubit composed of flying microwave qubit and superconducting qubit. We have demonstrated that for the hybrid qubit, the quantum controlled phase flip (CPF) gate can be reliably implemented for the experimentally available set of parameters.