Abstract One of the key challenges for the implementation of scalable quantum information processing is the design of scalable architectures that support coherent interaction and entanglement generation between distant quantum systems. We propose a nanotube double quantum dot spin transducer that allows to achieve steady-state entanglement between nitrogen-vacancy center spins in diamond with spatial separations up to micrometers. The distant spin entanglement further enables us to design a scalable architecture for solid-state quantum information processing based on a hybrid platform consisting of nitrogen-vacancy centers and carbon-nanotube double quantum dots.
Abstract One of the key challenges for the implementation of scalable quantum information processing is the design of scalable architectures that support coherent interaction and entanglement generation between distant quantum systems. We propose a nanotube double quantum dot spin transducer that allows to achieve steady-state entanglement between nitrogen-vacancy center spins in diamond with spatial separations up to micrometers. The distant spin entanglement further enables us to design a scalable architecture for solid-state quantum information processing based on a hybrid platform consisting of nitrogen-vacancy centers and carbon-nanotube double quantum dots.
Practical quantum information technique requires a large scalable quantum network. We proposed a hybrid system for deterministic scalable spin entanglement network based on nitrogen-vacancy (NV) centers in diamond coupling with carbon nanotube. The fault-tolerant entangled gate between two remote NV centers can be realized with vibrating nanotube assisted spin-spin interaction with current experimental technology. This interaction can be directly generalized to multi-NV-center entanglement architecture. Moreover, the effects of the single spin dephasing (SSD) and spin cross relaxation (SCR) on this state generation process were analyzed in detail. We found that the decay rate scales as N2, corresponding to the number of independent decoherence channels. However, by employing dressed state protection and independent tunable interaction method, SSD and SCR can be mitigated efficiently and the decay rate of the generated multi-NV-center entanglement scales as N, which boosts the size of the entanglement network up to hundreds of qubits. Such a hybrid quantum system compatible with current topological protection provides a useful platform for the investigation of quantum computation.
Nitrogen-vacancy (NV) centers in nanodiamond offer a promising platform for quantum information processing due to their room-temperature spin coherence and optical addressability. However, scalable quantum processors remain limited by the challenge of achieving strong, controllable interactions between distant NV spins. Here, we propose a scalable architecture utilizing optically levitated nanodiamond arrays, where torsional vibrations mediate the coherent coupling between the embedded NV centers. By optimizing the shape of ellipsoidal nanoparticles, we achieve a light-induced coupling strength exceeding 119 kHz between torsional modes of the distant levitated nanodiamonds, which are two orders of magnitude larger than the typical decoherence rates in this system. This strong interaction, combined with magnetic-field-enabled spin-torsion coupling, establishes an effective interaction between the spatially separated NV centers in the distant nanodiamonds. Numerical simulations confirm that dynamic decoupling can suppress both thermal noise and spin dephasing, enabling two-qubit gates with fidelity exceeding 99%. This work provides a foundation for reconfigurable quantum hybrid systems, with potential applications in rotational sensing and programmable quantum processing.
A design is proposed for scalable solid-state quantum computing, which is based on collectively enhanced magnetic coupling between nitrogen-vacancy center ensembles and superconducting transmission line resonators interconnected by current-biased Josephson junction superconducting phase qubit. In this hybrid system, we realize distant multi-qubit controlled phase gate operations and generate distant multi-qubit entangled W-like states, being indispensable resource to quantum computation. Our proposed architecture consists of solid-state spin ensembles and circuit QED, and could achieve quantum computing in a solid-state environment with high-fidelity and scalable way. The experimental feasibility is discussed, and the implementation efficiency is demonstrated numerically.
Physics
There are several different approaches to quantum information processing currently under development, including (but not exhaustively) superconducting circuits, nitrogen vacancy defects in diamond, and semiconductor quantum dots. Each one relies on the basic building block of a qubit, a two-level quantum system, on which the information can be stored and manipulated. In the semiconductor quantum dot approach, manipulating the spin of a single electron is promising because it has all the requirements: being fast, controllable and stable. A downside, however, has been the issue of scalability. Any useful quantum processor will require a system of many qubits, but getting quantum dots to talk to each other has presented a challenge. Addressing a preliminary point of this issue, Schaibley et al. show that the light (a single photon) emitted from the excited state of a charged quantum dot is entangled with the spin of the electron on the dot. The authors argue that by making the single photons emitted from other distinct quantum dots interact, it may be possible to then entangle the spins on these quantum dots and thus realize a scalable architecture.
Phys. Rev. Lett. 110 , 167401 (2013).
Hybrid quantum systems consisting of quantum dot spins and superconducting circuits have emerged as a promising platform for quantum information processing. However, the development of scalable architectures requires the ability to entangle different quantum systems over long distances, which remains an outstanding challenge for hybrid systems with complex interactions and multiple energy levels. Here, we devise methods to implement entangling gates by using engineered virtual photons as a transducer to couple spin-superconducting systems. We propose to tailor such transducers by tuning the driving pulse using shortcuts to adiabaticity. We demonstrate the realization of high-fidelity entangling gates of 99% in short timescales of a few tens of nanoseconds, and we show the robustness of this approach to control parameters. Furthermore, our method enables state transfer and remote entanglement between different modules of the hybrid system with fidelity exceeding the fault-tolerance threshold, thus demonstrating the scalability of this approach. These results pave the way for fast, high-fidelity quantum information processing on leading hybrid platforms.
Nitrogen-vacancy (NV) centers in diamond and superconducting qubits are two promising solid-state quantum systems for quantum science and technology, but the realization of controlled interfaces between individual solid-state spins and superconducting qubits remains fundamentally challenging. Here, we propose and analyze a hybrid quantum system consisting of a magnetic skyrmion, an NV center, and a superconducting qubit, where the solid-state qubits are both positioned in proximity to the skyrmion structure in a thin magnetic disk. We show that it is experimentally feasible to achieve strong (coherent or dissipative) coupling between the NV center and the superconducting qubit by using the as an intermediary. This allows coherent information transfer and nonreciprocal responses between the NV center and the superconducting qubit at the single quantum level with high controllability. The proposed platform provides a scalable pathway for implementing quantum protocols that synergistically exploit the complementary advantages of spin-based quantum memories, microwave-frequency superconducting circuits, and topologically protected magnetic excitations.