Angular-resolved Rabi oscillations of orthorhombic spins in a Co(II) molecular qubit.

Magnetic molecules are promising candidates for quantum information processing (QIP) due to their tunable electron structures and quantum properties. A high spin Co(II) complex, CoH2dota, is studied for its potential to be used as a quantum bit (qubit) utilizing continuous wave (CW) and pulsed electron paramagnetic resonance (EPR) spectroscopy at low temperature. On the X-band microwave energy scale, the system can be treated as an effective spin 1/2 with a strongly anisotropic g-tensor resulting from the significant spin-orbital coupling. An experimental and theoretical study is conducted to investigate the anisotropic Rabi oscillations of the two magnetically equivalent spin centres with different orientations in a single crystal sample, which aims to verify the relationship between the Rabi frequency and the orientation of the g-tensor. The findings of this study show that an effective quantum manipulation method is developed for orthorhombic spin systems.

Multiprocessing Quantum Computing through Hyperfine Couplings in Endohedral Fullerene Derivatives.

Magnetic molecules have shown great potential in quantum information processing due to the chemical tunablity of their quantum behaviors. Chemical derivatives of endohedral nitrogen fullerenes with long coherence time and rich energy levels were synthesized and studied to demonstrate the ability of multiprocessing in quantum information using electron magnetic resonance. After initialization of the 12-levelled spin system, subgroups of spin energy levels coursed by the hyperfine couplings can be selectively manipulated. The cooperatively combining of the parallel calculations enabled quantum error correction, increasing the correct rate by up to 17.82 %. Also, different subgroups of transitions divided by hyperfine coupling can be treated as independent qubits, and multi-task quantum computing were realized by performing Z-gate and X-gate simultaneously, which accelerates the overall gating speed.

Spin-Electric Coupling with Anisotropy-Induced Vanishment and Enhancement in Molecular Ferroelectrics.

Manipulating quantum properties by electric fields using spin-electric coupling (SEC) effects promises spatial addressability. While several studies about inorganic materials showing the SEC functionality have been reported, the vastly tunable crystal structures of molecular ferroelectrics provide a range of rationally designable materials yet to be exploited. In this work, Mn2+-doped molecular ferroelectrics are chosen to experimentally demonstrate the feasibility of achieving the quantum coherent SEC effect in molecular ferroelectrics for the first time. The electric field pulse applied between Hahn-echo pulses in electron paramagnetic resonance (EPR) experiments causes controllable phase shifts via manipulating of the zero-field splitting (ZFS) of the Mn(II) ions. Detailed investigations of the aMn crystal showed unexpected SEC vanishment and enhancement at different crystal orientations, which were elucidated by studying the spin Hamiltonian and magnetic anisotropy. With the enhanced SEC efficiency being achieved (0.68 Hz m/V), this work discovers an emerging material library of molecular ferroelectrics to implement coherent quantum control with selective and tunable SEC effects toward highly scalable quantum gates.

Implementation of Quantum Level Addressability and Geometric Phase Manipulation in Aligned Endohedral Fullerene Qudits.

Endohedral nitrogen fullerenes have been proposed as building blocks for quantum information processing due to their long spin coherence time. However, addressability of the individual electron spin levels in such a multiplet system of 4 S3/2 has never been achieved because of the molecular isotropy and transition degeneracy among the Zeeman levels. Herein, by molecular engineering, we lifted the degeneracy by zero-field splitting effects and made the multiple transitions addressable by a liquid-crystal-assisted method. The endohedral nitrogen fullerene derivatives with rigid addends of spiro structure and large aspect ratios of regioselective bis-addition improve the ordering of the spin ensemble. These samples empower endohedral-fullerene-based qudits, in which the transitions between the 4 electron spin levels were respectively addressed and coherently manipulated. The quantum geometric phase manipulation, which has long been proposed for the advantages in error tolerance and gating speed, was implemented in a pure electron spin system using molecules for the first time.

Amination of the Gd@C82 endohedral fullerene: tunable substitution effect on quantum coherence behaviors.

The core-shell structure of endohedral fullerene-based anisotropic magnetic molecules of high spin with long coherence time could help scale up quantum systems. In this research, by amination of Gd@C82 with morpholine, three derivatives are functionalized with 5, 7 and 9 morpholine groups providing an interesting model to investigate the relationship between the quantum coherence and the spin environment. The original radical located on the carbon cage is successfully quenched, affording a quantum phase memory times (T M) over 5 µs at 5 K. By increasing the number of substitution groups, spin-lattice relaxation times (T 1) also show significant enhancement due to the interaction variation between the molecules and the environments. We found that the T M of the three molecules show no obvious difference below 10 K, while they are limited by T 1 at higher temperatures. In this work, the variable functional groups are able to tune both T 1 and T M, offering the possibility for application of high-spin magnetic molecules in the field of quantum information processing.

Electric field manipulation enhanced by strong spin-orbit coupling: promoting rare-earth ions as qubits.

Quantum information processing based on magnetic ions has potential for applications as the ions can be modified in their electronic properties and assembled by a variety of chemical methods. For these systems to achieve individual spin addressability and high energy efficiency, we exploited the electric field as a tool to manipulate the quantum behaviours of the rare-earth ion which has strong spin-orbit coupling. A Ce:YAG single crystal was employed with considerations to the dynamics and the symmetry requirements. The Stark effect of the Ce3+ ion was observed and measured. When demonstrated as a quantum phase gate, the electric field manipulation exhibited high efficiency which allowed up to 57 π/2 operations before decoherence with optimized field direction. It was also utilized to carry out quantum bang-bang control, as a method of dynamic decoupling, and the refined Deutsch-Jozsa algorithm. Our experiments highlighted rare-earth ions as potentially applicable qubits because they offer enhanced spin-electric coupling which enables high-efficiency quantum manipulation.

Can Zero-Profile Cage Maintain the Cervical Curvature Similar to Plate-Cage Construct for Single-Level Anterior Cervical Diskectomy and Fusion?

OBJECTIVE: We sought to compare the clinical and radiologic outcomes after anterior cervical surgery between zero-profile (Zero-P) cage and plate-cage construct (PCC). METHODS: One-hundred and sixteen patients with single-level cervical disk herniation who underwent anterior cervical diskectomy and fusion between May 2015 and March 2017 were enrolled. They were divided into a Zero-P group (61 cases) and a PCC group (55 cases). At 1, 6, 12, and 24 months after the operation, routine follow-up evaluation was recommended including visual analog scale score and Japanese Orthopaedic Association score. The lateral x-ray film was performed at 1 and 24 months postoperatively. RESULTS: All 116 patients successfully completed the operation and achieved bone fusion. While there was no significant difference in the amount of bleeding between the 2 groups, the operation time of the Zero-P group was significantly shorter than that of the PCC group with statistically difference. The visual analog scale score and Japanese Orthopaedic Association score of the 2 groups at each follow-up interval postoperatively were significantly improved compared with that before operation; the difference was statistically significant (P < 0.05, respectively). While all the C2-7 cervical curvature, segmental Cobb angle, and height of adjacent vertebral body were lost at the 24-month follow-up, the significant difference was observed in the Zero-P group (P < 0.05, respectively). CONCLUSIONS: Compared with the Zero-P system, the PCC system provides a comparable clinical outcome. Although it showed the disadvantages in controlling the operation time and surgical bleeding, the radiologic outcome was better at the 2-year follow-up.

Single-Crystal Study of a Low Spin Co(II) Molecular Qubit: Observation of Anisotropic Rabi Cycles.

A mononuclear low spin ( S = 1/2) Co(II) molecule crystallized in a 4-fold symmetry is fully investigated by CW and pulsed EPR on a single crystal sample. The quantum phase memory time of the molecule around 1 µs at 5 K is direction-independent, while the Rabi oscillation frequency is anisotropic. The spin Hamiltonian analyses reveal that the anisotropic Landé factor and hyperfine tensor do not influence the anisotropy apparently when the microwave magnetic field is applied along a certain direction. It is considered that the possibly involved nuclear spin forbidden transitions may be responsible for the small distinction of Rabi frequencies in two directions.

Catalytic asymmetric de novo construction of dihydroquinazolinone scaffolds via enantioselective decarboxylative [4+2] cycloadditions.

The first de novo construction of enantioenriched dihydroquinazolinones via an intermolecular strategy has been established. This approach also represents the first catalytic asymmetric [4+2] cycloaddition of vinyl benzoxazinanones with sulfonyl isocyanates, which afforded chiral dihydroquinazolinones in high yields and excellent enantioselectivities (up to 98% yield, 99 : 1 er). This reaction not only confronts the great challenge in de novo construction of enantioenriched dihydroquinazolinone skeletons, but also advances the chemistry of decarboxylative cycloadditions involving vinyl benzoxazinanones.

Two Magnetic Switching Complexes Based on the Fe(II) Ion.

Two neutral mononuclear iron(II) complexes with different spin-crossover (SCO) properties, Fe(L1)2(SCN)2 (1) and Fe(L2)2(SCN)2 (2) (L1 = 2-(thiophen-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline and L2 = 2-(thiophen-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline), were solvothermally synthesized. With the different substituted position in 1,10-phenanthroline derivatives, 1 exhibits gradual SCO around room temperature with T1/2 = 280 K, while 2 displays abrupt SCO with 10 K hysteresis at T1/2↓ = 210 K and T1/2↑ = 220 K.

Effect of recombinant human bone morphogenetic protein 2/poly-lactide-co-glycolic acid (rhBMP-2/PLGA) with core decompression on repair of rabbit femoral head necrosis.

OBJECTIVE: To observe the effect of recombinant human bone morphogenetic protein 2/poly-lactide-co-glycolic acid (rhBMP-2/PLGA) with core decompression on repair of rabbit femoral head necrosis. METHOD: Bilateral femoral head necrosis models of rabbit were established by steroid injection. A total of 48 rabbits (96 femoral head necrosis) were randomly divided into 4 groups: Group A, control group with12 rabbits, 24 femoral head necrosis; Group B, treated with rhBMP-2/PLGA implantation after core depression, with 12 rabbits, 24 femoral head necrosis; Group C, treated with rhBMP-2 implantation after core depression, with 12 rabbits, 24 femoral head necrosis; Group D treated with core depression group without implantation, with 12 rabbits, 24 femoral head necrosis. All animals were sacrificed after 12 weeks. The ability of repairing bone defect was evaluated by X-ray radiograph. Bone mineral density analysis of the defect regions were used to evaluate the level of ossification. The morphologic change and bone formation was assessed by HE staining. The angiogenesis was evaluated by VEGF immunohistochemistry. RESULTS: The osteogenetic ability and quality of femoral head necrosis in group B were better than those of other groups after 12 weeks by X-ray radiograph and morphologic investigation. And the angiogenesis in group B was better than other groups. Group C had similar osteogenetic quality of femoral head necrosis and angiogenesis with group D. CONCLUSION: The treatment of rhBMP-2/PLGA implantation after core depression can promote the repair of rabbit femoral head necrosis. It is a promising and efficient synthetic bone material to treat the femoral head necrosis.