Dephasing-insensitive quantum information storage and processing with superconducting qubits

TL;DR

This paper introduces a method for protecting superconducting qubits from dephasing noise during quantum information storage and processing by using weak continuous driving fields, enabling high-fidelity gates in all-to-all connected circuits.

Contribution

It presents a novel dephasing-insensitive approach for quantum information storage and two-qubit gate implementation in superconducting circuits with frequency-tunable qubits.

Findings

Individual qubits can be dynamically decoupled from dephasing noise.

A new two-qubit phase gate with inherent dynamical decoupling was demonstrated.

Weak continuous driving fields protect qubits during gate operations.

Abstract

A central task towards building a practical quantum computer is to protect individual qubits from decoherence while retaining the ability to perform high-fidelity entangling gates involving arbitrary two qubits. Here we propose and demonstrate a dephasing-insensitive procedure for storing and processing quantum information in an all-to-all connected superconducting circuit involving multiple frequency-tunable qubits, each of which can be controllably coupled to any other through a central bus resonator. Although it is generally believed that the extra frequency tunability enhances the control freedom but induces more dephasing impact for superconducting qubits, our results show that any individual qubit can be dynamically decoupled from dephasing noise by applying a weak continuous and resonant driving field whose phase is reversed in the middle of the pulse. More importantly, we demonstrate a new method for realizing two-qubit phase gate with inherent dynamical decoupling via the combination of continuous driving and qubit-qubit swapping coupling. We find that the weak continuous driving fields not only enable the conditional dynamics essential for quantum information processing, but also protect both qubits from dephasing during the gate operation.