1. Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2AZ, London, UK
2. Quantum Engineering Centre for Doctoral Training, University of Bristol, 5 Tyndall Avenue, BS8 1FD, Bristol, UK
3. Quantum Engineering Technology Labs, H. H. Wills Physics Laboratory and Department of Electrical and Electronic Engineering, University of Bristol, BS8 1UB, Bristol, UK