UCL Quantum Science and Technology Institute


High quality-factor tunable resonators for quantum information storage

10 January 2019

Tunable Nb superconducting resonator based on a constriction nano-SQUID fabricated with a Ne focused ion beam.


High quality-factor tunable resonators underpin the storage and retrieval of microwave-domain quantum information into spin ensembles used as long-lived quantum memories and can enable multi-frequency high-sensitivity electron spin resonance (ESR). A team based at the London Centre for Nanotechnology has developed a single layer technology based on embedding nanoSQUIDs in superconducting niobium resonators to realise high quality frequency tunable devices which are resilient to moderate fields.

These devices will enable tunable-resonator-enhanced ESR protocols to be performed at specific magnetic fields and frequencies, such as storing quantum information in spins at low-decoherence “clock transitions”. The figure shows the resonant frequency of the superconducting resonator as applied field is swept. Inset is a circuit diagram of the tunable resonator including a HeFIB micrograph of the nanoSQUID embedded within the resonator. You can access the paper full text at: https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.11.014006