CNR NANO - Istituto Nanoscienze Consiglio Nazionale delle Ricerche

- 07.10.2021 - NANO COLLOQUIA 2021 S3 Seminar Claudio Bonizzoni

Date and Time: October 7, 2021 - 15.00

ONLINE https://global.gotomeeting.com/join/551814869

Speaker: Claudio Bonizzoni

Title: Coherent Manipulation and Readout of Molecular Spins through Microwave Planar Superconducting Resonators

Abstract:
Molecular spins hold potential for quantum technologies thanks to their long coherence time and the possibility of exploiting both electronic and nuclear spin degrees of freedom. The exploitation of such magnetic systems has come along with their successful integration into planar superconducting microwave resonators [1]. Along this line, our effort is focused on developing protocols (i.e. combinations of continuous-wave and/or pulsed-wave signals) for initializing, manipulating and reading out the systems. In this work we present our recent results concerning the spectroscopy of spin ensembles through planar superconducting microwave resonators at low temperature.
We first focus on the spectroscopy performed in the pulsed-wave regime, by considering a diluted Oxovanadyl (VO(TPP)) molecular spin ensemble [2]. We show that it possible to coherently manipulate it and to measure its phase memory time. We then test two Dynamical Decoupling protocols: Carr-Purcell-Meiboom-Gill and Uhrig Dynamical Decoupling. Both sequences are found to enhance the memory time of crystalline samples up to three times after the application of a low number (3,4) of π pulses, reaching up to 3 µs . We finally successfully implement a storage/retrieval protocol with up to 5 small, individually controllable, input pulses. This proof-of-principle result demonstrates the potential of molecular spins as (quantum) memories for information [2].
We then consider advanced transmission spectroscopy obtained by simultaneously applying two microwave tones. A crystal of diluted Diphenyl-Nitroxide (DPNO) organic radical in the dispersive limit of the coupling to the resonator, where no resonant exchange of photons occurs, is first considered [3]. We show that it is possible to measure the ensemble indirectly though the detuned resonator, with sufficient spectral resolution for electronic and nuclear spin transitions and with a little loss of spin sensitivity with respect to the resonant case. Moreover, the independent tunability of the two input powers used allows us to tune the signal-to-noise ratio of the measure [3]. We then show our preliminary results obtained on dual-mode resonator geometries coupled to spin ensembles [4], showing that two-tone spectroscopy can be used to implement advanced readout protocols.

[1] Bonizzoni et al. Adv. on Phys. X 3, 435305 (2018).
[2] Bonizzoni et al. NPJ Quantum Inf. 6, 68 (2020).
[3] Bonizzoni et al. Adv. Quantum Technol. 4, 2100039 (2021).
[4] Bonizzoni et al. Journ. Appl. Phys. 124, 194501 (2018).

Host: Massimo Rontani segreteria.s3@nano.cnr.it