A controllable two-qubit swapping gate using superconducting circuits

TL;DR

This paper proposes a superconducting circuit design for a controllable two-qubit swapping gate using a linear chain of qubits, demonstrating high fidelity and potential for simulating complex Hamiltonians.

Contribution

It introduces a novel superconducting circuit implementation of a controllable two-qubit swapping gate with detailed design and simulation results.

Findings

Achieved an average fidelity of around 0.99 in simulations.

Demonstrated control of the gate operation via circuit parameters.

Showed potential for simulating Hamiltonians with topological properties.

Abstract

In this paper we investigate a linear chain of qubits and determine that it can be configured into a conditional two-qubit swapping gate, where the first and last qubits of the chain are the swapped qubits, and the remaining middle ancilla qubits are controlling the state of the gate. The swapping gate introduces different phases on the final states depending on the initial states. In particular we focus on a chain of four qubits and show the swapping gate it implements. We simulate the chain with realistic parameters, and decoherence noise and leakage to higher excited states, and find an average fidelity of around 0.99. We propose a superconducting circuit which implements this chain of qubits and present a circuit design of the circuit. We also discuss how to operate the superconducting circuit such that the state of the gate can be controlled. Lastly, we discuss how the circuit can be straightforwardly altered and may be used to simulate Hamiltonians with non-trivial topological properties.