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

Zheng Liu,Ye-Xin Wang,Si-Xue Qin,Shang-Da Jiang,Yu-Hui Fang,Zhe-Ming Wang,Song Gao

doi:10.1093/nsr/nwaa148

Abstract

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.

Highlights

Quantum computation offers accelerated ways of solving problems such as database searching[1] and prime factor decomposition[2]
We report largely enhanced spin-electric coupling in rare-earth ions, with which the coherent control by the electric field (E field) is illustrated as a phase gate
We have demonstrated that an E field pulse applied to the Ce:yttrium aluminium garnet (YAG) can be a highly efficient quantum phase gate

Summary

Introduction

Quantum computation offers accelerated ways of solving problems such as database searching[1] and prime factor decomposition[2]. We report largely enhanced spin-electric coupling in rare-earth ions, with which the coherent control by the E field is illustrated as a phase gate. Using this electric phase gate, quantum bang-bang decoupling is realized with microwave (mw) pulses, and the refined Deutsch-Jozsa (D-J) algorithm is demonstrated. Where the three terms represent the Zeeman splitting, the spin-orbit coupling and the crystal field effect, which results basically from the electrostatic field around the ion. A recent research concludes that, with similar structures, the spinorbit coupling is not the primary factor leading to decoherence[20] This ensures the possibility to employ strong spin-orbit coupling systems as qubits while maintaining long quantum coherence time. By applying the ac E field to the sample continuously, the electron paramagnetic resonance (EPR) spectra showed a shift of the effective g-factor up to -2.5×10-6

Results and discussions

Conclusion

Conflicts of interest