Universal distributed blind quantum computing with solid-state qubits (2412.03020v2)

Abstract: Blind quantum computing (BQC) is a promising application of distributed quantum systems, where a client can perform computations on a remote server without revealing any details of the applied circuit. While the most promising realizations of quantum computers are based on various matter qubit platforms, implementing BQC on matter qubits remains an outstanding challenge. Using silicon-vacancy (SiV) centers in nanophotonic diamond cavities with an efficient optical interface, we experimentally demonstrate a universal quantum gate set consisting of single- and two-qubit blind gates over a distributed two-node network. Using these ingredients, we perform a distributed algorithm with blind operations across our two-node network, paving the way towards blind quantum computation with matter qubits in distributed, modular architectures.

• The paper demonstrates universal blind quantum computing by implementing single- and two-qubit gates using SiV centers with up to 94.8% fidelity.
• The protocol enables secure remote quantum operations while concealing client circuit designs with minimal information leakage.
• A distributed Deutsch–Jozsa algorithm validates the approach, highlighting its potential for scalable, privacy-preserving quantum networks.

An Analysis of Universal Distributed Blind Quantum Computing with Solid-State Qubits

The paper "Universal distributed blind quantum computing with solid-state qubits" presents a significant advancement in the development of blind quantum computing (BQC) by leveraging solid-state qubits. The authors outline a novel experimental approach using silicon-vacancy (SiV) centers in diamond nanophotonic cavities, achieving a universal set of quantum gates over a distributed network. This accomplishment not only serves as a milestone in quantum computing but also enhances the practical potential for secure computations over remote servers without revealing circuit designs.

Summary of Results

1. Blind Quantum Computation with Matter Qubits: Utilizing SiV centers, which offer an efficient matter-photon interface, the researchers demonstrate a universal quantum gate set composed of single- and two-qubit blind gates. This implementation facilitates remote execution of quantum algorithms while preserving client's privacy.
2. Single-Qubit and Two-Qubit Blind Gates:
   • A single-qubit blind gate (1QBG) using spin-photon gates to perform rotations with client-defined angles.
   • Two-qubit blind gates (2QBG), both intra-node (within a single server) and inter-node (between different servers), extend operations to entangling gates such as the controlled-Z (CZ) gate. The intra-node gates are facilitated by entanglement between qubits within the same node, while the inter-node gates bridge separate nodes, critical for distributed architectures.
3. Performance Metrics: The experiments showcased high average gate fidelities, such as 94.8% for single-qubit operations. Moreover, the approach maintains low information leakage, characterized using the Holevo information metric, suggesting the server cannot discern the client's operations.
4. Distributed Algorithm Demonstration: The realization of a Deutsch-Jozsa-type algorithm, where oracles are applied blind to observers, exemplifies practical applications of BQC with solid-state qubits. The client identifies whether an oracle's function is constant or balanced through a single query, leveraging quantum parallelism.

Implications and Future Directions

The implications of these results are manifold. The experimental evidence of secure distributed quantum computing using matter qubits marks a pivotal step toward scalable quantum networks. The realization of quantum operations with low information leakage further highlights the potential of such platforms for privacy-preserving quantum computations.

Furthermore, integrating robust quantum memories could enhance scalability and determinism in BQC protocols. By achieving interoperability across varying quantum systems, the scalability of quantum computational architectures can be broadened, leading to more complex and error-resilient computations.

Additionally, emerging platforms such as trapped ions and superconducting circuits could also adopt these methods to enhance their own BQC capabilities. The flexibility and reduced photon overhead inherent in the described solid-state approach could inform design strategies across various quantum architectures.

Conclusively, the practical realization of universal distributed BQC presents significant promise in advancing cryptographic applications and secure computational services, potentially transforming how sensitive computations are managed and executed across quantum networks.