Southwest Quantum Information and Technology

Strong parametric dispersive shifts in a statically decoupled multi-qubit cavity QED system

Presenting Author: Taewan Noh, National Institute of Standards and Technology, Boulder
Contributing Author(s): Zhihao Xiao, Xiaoyue Jin, Katarina Cicak, Emery Doucet, Jose Aumentado, Luke Govia, Leonardo Ranzani, Archana Kamal, Raymonds Simmonds.

Engineering dispersive interactions in cavity quantum electrodynamic (QED) systems is important for developing high fidelity qubit measurement, fast logic gates, state preparation and error correction protocols. In this talk, we describe our experiments with two transmon qubits coupled to a lumped element cavity through a shared dc-SQUID. We show that our system can provide protection from decoherence processes for both qubits by minimizing coupling to the readout cavity during qubit operations. Parametric driving of the SQUID with an oscillating magnetic flux enables independent, dynamical tuning of the qubit-cavity interactions for both qubits. The strength and detuning of this interaction can be fully controlled through the choice of the parametric pump frequency and amplitude. As a practical demonstration, we present the result of pulsed parametric dispersive readout of each qubit while statically decoupled from the cavity. Furthermore, we show that it is possible to perform joint-readout of two-qubit states using our parametric approach. In addition to realizing many features of standard cavity QED, this parametric scheme creates a new tunable cavity QED framework for developing quantum information systems with various future applications, such as entanglement and error correction via multi-qubit parity readout, state and entanglement stabilization, and parametric logical gates.

Read this article online: https://arxiv.org/abs/2103.09277

(Session 5 : Thursday from 12:00pm-2:00 pm)