Yongbin Hu

High-fidelity quantum memory using nitrogen-vacancy center ensemble for hybrid quantum computation

We study a hybrid quantum computing system using a nitrogen-vacancy center ensemble (NVE) as quantum memory, a current-biased Josephson junction (CBJJ) superconducting qubit fabricated in a transmission line resonator (TLR) as the quantum computing processor, and the microwave photons in TLR as the quantum data bus. The storage process is seriously treated by considering all kinds of decoherence mechanisms. Such a hybrid quantum device can also be used to create multiqubit W states of NVEs through a common CBJJ. The experimental feasibility is achieved using currently available technology.

Preparation of cluster states with endohedral fullerenes in single-walled carbon nanotubes

We propose two scalable methods for generation of cluster states with arrays of endohedral fullerenes N-15@C-60 residing in single-walled carbon nanotubes (SWCNTs) using direct and indirect methods, respectively. The direct method makes use of a series of controlled-phase flip (CPF) gates by electron spin resonance pulses of selective frequencies and durations, where the CPF gates are realized by magnetic-dipole couplings between the electron spins of the nearest-neighbour fullerenes in SWCNTs. The indirect method resorts to auxiliary mobile electron as the flying qubit, which transfers quantum information from one site to another. This greatly releases the requirements for the distance between fullerenes in SWCNTs. The decoherence effect and experimental feasibility are also discussed based on currently available technology.