Broad-band spectroscopy of a vanadyl porphyrin: a model electronuclear spin qudit

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.

Transmission Spectroscopy of Molecular Spin Ensembles in the Dispersive Regime

“…Since the spin ensemble is driven without a resonant mode, it is also interesting to compare our technique with on‐chip single‐tone broadband MW spectroscopy. [ 65–68 ] In these latter experiments a single MW tone is injected into a coplanar or a microstrip transmission line (i.e., no resonant MW modes) and used as a probe tone, to monitor the variation of the transmission induced by the ensemble. Broadband transmission spectroscopy offers large tunability of the frequency (several gigahertz), which can be used to map the energy levels of the spin ensemble as a function of the static magnetic field.…”

“…Broadband transmission spectroscopy offers large tunability of the frequency (several gigahertz), which can be used to map the energy levels of the spin ensemble as a function of the static magnetic field. [ 65,68 ] In our two‐tone spectroscopy, the dispersive shift of the cavity scales as the inverse of the detuning with respect to the probing cavity mode (Equation (3)), giving a lower tunability for the drive frequency. However, the dispersive shift depends also by the coupling rate providing that an optimal working point can be found in the tradeoff between detuning and magnetic coupling.…”

“…In addition, the background of broadband spectroscopy depends on the losses of transmission line (which mainly give a sloped baseline as a function of frequency) and on the presence of spurious resonances (e.g., box modes, magnetic impurities). [ 65–68 ] The signal given by the sample is typically obtained after the normalization of the transmission over a (carefully chosen) reference baseline taken in non‐zero field. Our dispersive spectroscopy less suffers of such effects because of the following reasons: i) the resonator is typically designed to be far enough in energy with respect to box or spurious modes, ii) the smaller frequency range used gives flatter backgrounds and, iii) the signal given by eventual magnetic impurities can be naturally suppressed by the dependence of Equation (3).…”

Controlled coherent dynamics of [VO(TPP)], a prototype molecular nuclear qudit with an electronic ancilla

“…Indeed, it provides a large spin (I ¼ 7/2, eight levels) nuclear qudit, coupled by hyperne interaction to an electronic spin 1/2. Recent studies on the same 45,46 and very similar compounds 47 have reported remarkable electron spin coherence times, thus suggesting this system also as a very promising candidate qudit. However, to actually demonstrate this, we now need to focus on nuclear spin degrees of freedom.…”

Radiofrequency to Microwave Coherent Manipulation of an Organometallic Electronic Spin Qubit Coupled to a Nuclear Qudit

“… 9 − 12 , 39 , 41 , 62 Recent studies further pointed out that in spite of the small quadrupole interaction typical of 51 V nucleus (and 3d metal ions in general), hyperfine coupling yields a pattern of levels which can be reproduced by an effective quadrupolar splitting along specific magnetic field directions. 63 This energy level structure gives full control of the system by radiofrequency (rf) pulses resonant with single-quantum transitions. 64…”