Broad-band spectroscopy of a vanadyl porphyrin: a model electronuclear spin qudit. Issue 15 (17th March 2021)

• Record Type: Journal Article
• Authors: Gimeno, Ignacio; Urtizberea, Ainhoa; Román-Roche, Juan; Zueco, David; Camón, Agustín; Alonso, Pablo J.; Roubeau, Olivier; Luis, Fernando
• Is Part Of: Chemical science. Volume 12:Issue 15(2021)
• Page Start: 5621
• Page End: 5630
• Publication Date: 2021-03-17
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d1sc00564b
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : We show that a sizeable electronuclear entanglement of the S = 1/2 and I = 7/2 spins of a vanadyl porphyrin provides the conditions to act as a universal 4-qubit processor, and thus implement quantum error correction at the molecular level. Abstract : We explore how to encode more than a qubit in vanadyl porphyrin molecules hosting a S = 1/2 electronic spin coupled to a I = 7/2 nuclear spin. The spin Hamiltonian and its parameters, as well as the spin dynamics, have been determined via a combination of electron paramagnetic resonance, heat capacity, magnetization and on-chip magnetic spectroscopy experiments performed on single crystals. We find low temperature spin coherence times of micro-seconds and spin relaxation times longer than a second. For sufficiently strong magnetic fields ( B > 0.1 T, corresponding to resonance frequencies of 9–10 GHz) these properties make vanadyl porphyrin molecules suitable qubit realizations. The presence of multiple equispaced nuclear spin levels then merely provides 8 alternatives to define the '1' and '0' basis states. For lower magnetic fields ( B < 0.1 T), and lower frequencies (<2 GHz), we find spectroscopic signatures of a sizeable electronuclear entanglement. This effect generates a larger set of allowed transitions between different electronuclear spin states and removes their degeneracies. Under these conditions, we show that each molecule fulfills the conditions to act as a universal 4-qubit processor or, equivalently, as a d = 16 qudit. These findings widen the catalogue of chemically designed systems able to implement non-trivial quantum functionalities, such as quantum simulations and, especially, quantum error correction at the molecular level.