Unveiling the Effect of Magnetic Noise in the Coherence of Single-Molecule Quantum Processors

Quantum bits (qubits) constitute the most elementary building-blocks of any quantum technology, where information is stored and processed in the form of quantum superpositions between discrete energy levels. In particular, the fabrication of quantum processors is a key long-term goal that will allow us conducting specific tasks much more efficiently than the most powerful classical computers can do. Motivated by recent experiments in which three addressable spin qubits are defined on a potential single-molecule quantum processor, namely the [Gd(H2O)P5W30O110]12− polyoxometalate, we investigate the decohering effect of magnetic noise on the encoded quantum information. Our state-of-the-art model, which provides more accurate results than previous estimates, show a noticeable contribution of magnetic noise in limiting the survival timescale of the qubits. Yet, our results suggest that it might not be the only dephasing mechanism at play but other mechanisms, such as lattice vibrations and physical movement of magnetic nuclei, must be considered to understand the whole decoherence process

Field-Induced Slow Magnetic Relaxation In the First Dy(III)-centered 12-Metallacrown-4 Double-Decker

The reaction of Dy(O2CMe)3•xH2O and Ga(NO3)3•xH2O led to the isolation of (nBu4N)[GaIII8DyIII(OH)4(shi)8] (1). The compound possesses a unique chemical structure enclosing the central magnetic DyIII ion between diamagnetic GaIII-based metallacrown 12-MC-4 ligands. The double-decker complex exhibits field-induced single-molecule magnet (SMM) behaviour with an effective energy barrier (Ueff) of 39 K (27.1 cm-1). Consistent with the observed slow relaxation of magnetization, theoretical calculations suggest a ground state mainly determined by |±11/2> in the easy axis direction

The use of electrochemical sensors for monitoring urban air quality in low-cost, high-density networks

Measurements at appropriate spatial and temporal scales are essential for understanding and monitoring spatially heterogeneous environments with complex and highly variable emission sources, such as in urban areas. However, the costs and complexity of conventional air quality measurement methods means that measurement networks are generally extremely sparse. In this paper we show that miniature, low-cost electrochemical gas sensors, traditionally used for sensing at parts-per-million (ppm) mixing ratios can, when suitably configured and operated, be used for parts-per-billion (ppb) level studies for gases relevant to urban air quality. Sensor nodes, in this case consisting of multiple individual electrochemical sensors, can be low-cost and highly portable, thus allowing the deployment of scalable high-density air quality sensor networks at fine spatial and temporal scales, and in both static and mobile configurations.This work was supported by EPSRC (grant number EP/E002102/1) and the Department for Transport

Viaje a un universo de dos dimensiones

La tabla periódica ofrece numerosas vías para crear materiales de uno o pocos átomos de espesor. Las singulares propiedades de estas estructuras bidimensionales están revolucionando la nanociencia

Zweidimensionale Revolution

Forscher entdecken immer mehr Stoffe, die nur eine einzige Atomlage dick sind – und oft un­gewöhnliche Merkmale aufweisen. ­Zudem kann man diese Schichten übereinanderlegen. ­Dadurch entstehen ultradünne Strukturen mit spannenden neuen Eigenschaften

Exploring High-Symmetry Lanthanide-Functionalized Polyoxopalladates as Building Blocks for Quantum Computing

The structural, electronic and magnetochemical properties of the star-shaped polyoxopalladate [Pd15O10(SeO3)10]10− (POPd) and its lanthanide functionalized derivatives have been investigated on the basis of density functional theory followed by a ligand field analysis using the Radial Effective Charge (REC) model. Our study predicts that heteroPOPd is a robust cryptand that enforces D5h symmetry around the encapsulated Ln3+ centers. This rigid coordination environment favors interesting potential magnetic behavior in the Er and Ho derivatives, which may be of interest for molecular spintronics and quantum computing applications.status: publishe

Exploring the transport properties of equatorially low-coordinated erbium single ion magnets

Single-molecule spin transport represents the lower limit of miniaturization of spintronic devices. These experiments, although extremely challenging, are key to understand the magneto-electronic properties of a molecule in a junction. In this context, theoretical screening of new magnetic molecules provides invaluable knowledge before carrying out sophisticated experiments. Herein, we investigate the transport properties of three equatorially low-coordinated erbium single ion magnets with C3v symmetry: Er[N(SiMe3⁠)2⁠]3⁠ (1), Er(btmsm)3⁠ (2) and Er(dbpc)3⁠ (3), where btmsm=bis(trimethylsilyl)methyl and dbpc=2,6-di-tert-butyl-p-cresolate. Our ligand field analysis, based on previous spectroscopic data, confirms a ground state mainly characterized by MJ =±15/2 in all three of them. The relaxation of their molecular structures when placed between two Au (111) electrodes leads to an even more symmetric ∼D⁠3h environment, which ensures that these molecules would retain their single-molecule magnet behavior in the device setup. Hence, we simulate spin dependent transport using the DFT optimized structures on the basis of the non-equilibrium Green’s function formalism, which, in 1 and 2, suggests a remarkable molecular spin filtering under the effect of an external magnetic field

A magnetic study of a layered lanthanide hydroxide family: Ln₈(OH)₂₀Cl₄·nH₂O (Ln = Tb, Ho, Er)

Three layered lanthanide hydroxides (LLHs), with the general formula Ln8(OH)20Cl4·nH2O (Ln = Tb (1), Ho (2), Er (3)), were prepared and magnetically characterized. These compounds were further diluted within a yttrium diamagnetic matrix, LYH:xLn, LYH:0.044Tb (1’), LYH:0.045Ho (2’), and LYH:0.065Er (3’), being the study complemented with theoretical calculations in order to understand the electronic configuration and the contributions to the slow relaxation behavior. In the pure compounds dominant 3D ferromagnetic interactions are observed, with a small magnetization hysteresis at 1.8 K for 1, while the magnetically diluted solid solutions display slow relaxation of the magnetization at low temperatures

Model Studies on the Photochemistry of Phenolic Sulfonate Photoacid Generators

The mechanism of photodissociation and acid generation for three phenolic sulfonate esters, ranging from alkyl, to benzyl, to aromatic, was investigated by laser flash photolysis and product studies. All the sulfonate esters studied showed the presence of phenoxyl and other complex radicals in the transient spectra. The formation of these complex transients indicates that the radical pair formed upon excitation of the sulfonate can escape the solvent cage, and undergo further chemical transformations. It was observed that all of the sulfonate esters investigated resulted in the formation of acidic species. Photoproduct studies indicate that phenyl methanesulfonate and phenyl toluene-p-sulfonate undergo a photo-Fries type rearrangement and also produce a large excess of phenol with the corresponding sulfonic acid. Upon excitation, phenyl toluene-α-sulfonate undergoes near quantitative SO extrusion, with the formation of no Fries rearrangement photoproducts; instead it was observed that the benzyl radicals, generated by SO loss, undergo a "pseudo" Fries rearrangement to form the ortho and para phenylmethane isomers. Further, the SO photogenerated undergoes oxidative and hydrolytic processes to form sulfuric and sulfurous acids

Quantum coherent spin-electric control in a molecular nanomagnet at clock transitions

Electrical control of spins at the nanoscale offers significant architectural advantages in spintronics, because electric fields can be confined over shorter length scales than magnetic fields1,2,3,4,5. Thus, recent demonstrations of electric-field sensitivities in molecular spin materials6,7,8 are tantalizing, raising the viability of the quantum analogues of macroscopic magneto-electric devices9,10,11,12,13,14,15. However, the electric-field sensitivities reported so far are rather weak, prompting the question of how to design molecules with stronger spin–electric couplings. Here we show that one path is to identify an energy scale in the spin spectrum that is associated with a structural degree of freedom with a substantial electrical polarizability. We study an example of a molecular nanomagnet in which a small structural distortion establishes clock transitions (that is, transitions whose energy is to first order independent of the magnetic field) in the spin spectrum; the fact that this distortion is associated with an electric dipole allows us to control the clock-transition energy to an unprecedented degree. We demonstrate coherent electrical control of the quantum spin state and exploit it to independently manipulate the two magnetically identical but inversion-related molecules in the unit cell of the crystal. Our findings pave the way for the use of molecular spins in quantum technologies and spintronics