# Entanglement generation in superconducting qubits using holonomic operations

**Authors:** Daniel J. Egger, Marc Ganzhorn, Gian Salis, Andreas Fuhrer, Peter Mueller, Panagiotis Kl. Barkoutsos, Nikolaj Moll, Ivano Tavernelli, Stefan Filipp  
**arXiv:** [1804.04900](https://arxiv.org/abs/1804.04900)  
**Date:** 2018-04-13  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/1804.04900v1/

## Key points

- Egger et al. explore a novel non-adiabatic holonomic operation for entangling fixed-frequency superconducting transmon qubits
- Coherent microwave tones applied simultaneously induce transitions between resonator states of the qubits
- Holonomic operation entangles qubits with 95% fidelity in just 213 ns
- Limitation in achieving higher fidelity is charge-noise in current device setup
- Potential for implementing SWAP-type gate within an all-microwave controlled hardware platform
- Proposed scheme expands repertoire of two-qubit operations, opening new avenues for quantum applications and variational algorithms
- Research represents a crucial step forward in practical quantum information processing tasks and innovation in quantum computing methodologies

## Summary

In their study, Egger et al. explore a novel non-adiabatic holonomic operation that enables efficient entanglement of fixed-frequency superconducting transmon qubits connected to a shared bus resonator. By applying coherent microwave tones simultaneously to both qubits, transitions between the first excited resonator state and the second excited state of each qubit are induced. This cyclic evolution within an effective 3-level $\Lambda$-system leads to a holonomic operation that successfully entangles the two qubits with an impressive fidelity of 95% in just $213~\rm{ns}$. The primary limitation in achieving even higher fidelity lies in the charge-noise inherent to the current device setup. However, this work holds significant potential for implementing a SWAP-type gate directly within an all-microwave controlled hardware platform. By expanding the repertoire of available two-qubit operations within the fixed-frequency qubit architecture, this proposed scheme opens up new avenues for near-term quantum applications and could prove invaluable in leveraging variational algorithms for efficient creation of problem-specific trial states. Overall, Egger and colleagues' research represents a crucial step forward in harnessing advanced quantum techniques for practical quantum information processing tasks and holds promise for driving innovation in quantum computing methodologies and applications.