Observation of Photon Blockade in a Tavis-Cummings System

TL;DR

This paper reports the experimental observation of photon blockade in a superconducting cavity coupled to multiple transmon qubits, demonstrating quantum control over microwave photons and confirming Tavis-Cummings model predictions.

Contribution

First experimental demonstration of photon blockade in a multi-qubit Tavis-Cummings system with photon number-resolving spectroscopy.

Findings

Observation of polariton formation with splitting proportional to √N

Detection of sub-Poissonian photon statistics in the cavity

Confirmation of Tavis-Cummings coupling dynamics

Abstract

We observe blockade of microwave photons in a Tavis-Cummings system comprising a superconducting cavity and up to $N=3$ transmon qubits. The effect is characterized with photon number-resolving spectroscopy using an additional dispersively coupled transmon "witness" qubit to directly probe the cavity's photon number distribution. We first observe polariton formation with splitting proportional to $\sqrt{N}$, confirming the Tavis-Cummings coupling, and subsequently obtain sub-Poissonian cavity photon statistics when the cavity is driven at polariton frequencies.