Dressed Collective Qubit States and the Tavis-Cummings Model in Circuit QED

TL;DR

This paper demonstrates a precise implementation of the Tavis-Cummings model using superconducting qubits in circuit QED, enabling exploration of collective quantum states with fixed atom numbers and scalable quantum information applications.

Contribution

It introduces a novel, controllable setup for studying collective qubit states and their scaling properties in circuit QED without atom number fluctuations.

Findings

Observed the discrete square root of N scaling of coupling strength.

Demonstrated control over bright and dark collective states.

Explored multi-qubit states like the W-state in a scalable system.

Abstract

We present an ideal realization of the Tavis-Cummings model in the absence of atom number and coupling fluctuations by embedding a discrete number of fully controllable superconducting qubits at fixed positions into a transmission line resonator. Measuring the vacuum Rabi mode splitting with one, two and three qubits strongly coupled to the cavity field, we explore both bright and dark dressed collective multi-qubit states and observe the discrete square root of N scaling of the collective dipole coupling strength. Our experiments demonstrate a novel approach to explore collective states, such as the W-state, in a fully globally and locally controllable quantum system. Our scalable approach is interesting for solid-state quantum information processing and for fundamental multi-atom quantum optics experiments with fixed atom numbers.