Coherent control of a flux qubit by phase-shifted resonant microwave pulses

TL;DR

This paper demonstrates a method for precise, phase-shifted microwave pulse control of a flux qubit, enabling arbitrary axis rotations and faster quantum gate operations without detuning.

Contribution

It introduces a phase-shifted resonant microwave technique for coherent flux qubit control, allowing arbitrary axis rotations and potential speed improvements in quantum gates.

Findings

Successfully observed Ramsey fringes with phase-shifted pulses

Achieved coherent oscillations at 2pi*11.4 Grad/s angular velocity

Enabled full single-qubit control with potential for faster gates

Abstract

The quantum state of a flux qubit was successfully pulse-controlled by using a resonant microwave. We observed Ramsey fringes by applying a pair of phase-shifted pi/2 microwave pulses without introducing detuning. With this method, the qubit state can be rotated on an arbitrary axis in the x-y plane of the Bloch sphere in a rotating frame. We obtained a qubit signal from a coherent oscillation with an angular velocity of up to 2pi*11.4 Grad/s. In combination with Rabi pulses, this method enables us to achieve full control of single qubit operation. It also offers the possibility of orders of magnitude increases in the speed of the arbitrary unitary gate operation.