Multiqubit quantum phase gate using four-level superconducting quantum interference devices coupled to superconducting resonator

TL;DR

This paper presents a fast, scalable scheme for implementing multiqubit quantum phase gates using four-level SQUIDs coupled to a resonator, avoiding complex adjustments and applicable to quantum Fourier transforms.

Contribution

It introduces a novel, efficient method for multiqubit quantum phase gates with no need for adiabatic passage or level adjustment, applicable to n-qubit systems.

Findings

Successfully implements three-qubit quantum phase gate.

Generalizes scheme for arbitrary n-qubit gates.

Demonstrates application to quantum Fourier transform.

Abstract

In this paper, we propose a scheme to realize three-qubit quantum phase gate of one qubit simultaneously controlling two target qubits using four-level superconducting quantum interference devices (SQUIDs) coupled to a superconducting resonator. The two lowest levels |0> and |1> of each SQUID are used to represent logical states while the higher energy levels |2> and |3> are utilized for gate realization. Our scheme does not require adiabatic passage, second order detuning, and the adjustment of the level spacing during gate operation which reduce the gate time significantly. The scheme is generalized for an arbitrary n-qubit quantum phase gate. We also apply the scheme to implement three-qubit quantum Fourier transform. key words: quantum phase gate, superconducting quantum interference devices (SQUIDs), superconducting resonator, quantum Fourier transform