Here we extend the concept of blind client-server quantum computation, in which a client with limited quantum power controls the execution of a quantum computation on a powerful server, without revealing any details of the computation. Our extension is to introduce a three-node setting in which an oracular quantum computation can be executed blindly. In this Blind Oracular Quantum Computation (BOQC), the oracle (Oscar) is another node, with limited power, who acts in cooperation with the client (Alice) to supply quantum information to the server so that the oracle part of the quantum computation can also be executed blindly. We develop tests of this protocol using two- and three-qubit versions of the exact Grover algorithm (i.e., with database sizes $4\leq N\leq 8$), obtaining optimal implementations of these algorithms within a gate array scheme and the blinded cluster-state scheme. We discuss the feasibility of executing these protocols in state-of-the-art three-node experiments using NV-diamond electronic and nuclear qubits.
Here we extend the concept of blind client-server quantum computation, in which a client with limited quantum power controls the execution of a quantum computation on a powerful server, without revealing any details of the computation. Our extension is to introduce a three-node setting in which an oracular quantum computation can be executed blindly. In this Blind Oracular Quantum Computation (BOQC), the oracle (Oscar) is another node, with limited power, who acts in cooperation with the client (Alice) to supply quantum information to the server so that the oracle part of the quantum computation can also be executed blindly. We develop tests of this protocol using two- and three-qubit versions of the exact Grover algorithm (i.e., with database sizes 4≤N≤8), obtaining optimal implementations of these algorithms within a gate array scheme and the blinded cluster-state scheme. We discuss the feasibility of executing these protocols in state-of-the-art three-node experiments using NV-diamond electronic and nuclear qubits.
Here we put into practice the concept of blind client-server quantum computation, in which a client with limited quantum power controls the execution of a quantum computation on a powerful server, without revealing any details of the computation. In particular, it is a three-node setting in which an oracular quantum computation can be executed blindly. In this Blind Oracular Quantum Computation (BOQC), the oracle (Oscar) is another node, with limited power, who acts in cooperation with the client (Alice) to supply quantum information to the server so that the oracle part of the quantum computation can also be executed blindly. We develop tests of this protocol using two- and three-qubit versions of the exact Grover algorithm (i.e., with database sizes $4\ensuremath{\le}N\ensuremath{\le}8$), obtaining optimal implementations of these algorithms within a gate array scheme and the blinded cluster-state scheme. We discuss the feasibility of executing these protocols in state-of-the-art three-node experiments using nitrogen-vacancy diamond electronic and nuclear qubits.
Recent years have seen much excitement for application of quantum computing, triggered by substantial — and ongoing — advances in experimental realizations of quantum computing. It is widely believed that client-server is the setting for quantum computers that will prevail in the future, where privacy becomes crucial in the application. Moreover, a recent experiment by Barz et al. [1] successfully demonstrated a blind quantum computation scheme: a client-server quantum computation in which a client with limited quantum power controls the execution of a quantum computation on a powerful server, without revealing valuable details of the computation. In this thesis, we discuss the Blind Oracular Quantum Computation (BOQC) scheme, a blind quantum computing scheme in which a third party (the oracle)with limited quantum power, assists the execution of a client’s oracular quantum computations by implementing oracle evaluations. In BOQC, a client with limited quantum power and without the capacity to construct the oracle, can delegate her oracular quantum computations to a powerful yet untrustworthy server, with the help of the oracle. We show that BOQC is provably blind within a composable definition such that the server cannot learn about the clients’ computation. We provide a realization of BOQC in a physical setting, particularly in a diamond nitrogen-vacancy (NV) center platform. In BOQC, the server has a One-Way Quantum Computer (1WQC) that is resource-demanding. To lower the resource-requirements, we develop the BOQCo protocol, a BOQC that employs lazy 1WQC to minimize the number of qubits needed. We also provide systematic numerical optimization to find resource states that are BOQC-compatible by admitting BOQC security criteria. Finally, we give explicit oracular quantum algorithms that are BOQC-compatible to be executed on the NV-center platform. The algorithms include 2-qubit Grover’s algorithm using three qubits, 3-qubit exact Grover’s algorithm using four qubits, 2-qubit Simon’s algorithm with a useless oracle using four qubits, and Deutsch’s algorithm using three physical qubits. We hope that these BOQC algorithms intrigue some experimentalists to try to implement them.[1] S. Barz et al. “Demonstration of Blind Quantum Computing”. In: Science 335.6066 (2012), pp. 303–308.
Current cloud-based quantum processors offer access to advanced hardware hosted on a remote server, but do not guarantee data or algorithm privacy. Blind quantum computation provides information-theoretic privacy by enabling a client to execute an algorithm without disclosing information about either the task or the final result. Here, we execute a measurement-based blind quantum computation protocol on a superconducting processor comprising two flip-chip-bonded modules, one acting as a server and the other as a client. The server generates a two-dimensional cluster state and forwards it to the client. Using this resource, the client implements a universal gate set with only adaptive single-qubit rotations and measurements. To illustrate this approach, we execute a three-qubit instance of the Deutsch-Jozsa algorithm. We analyze the server's quantum state after each rotation of a measurement-based single-qubit gate to verify that negligible information about the computation is revealed to the server, consistent with the one-way flow of information that guarantees blindness. This proof-of-principle demonstration establishes key elements of blind quantum computation in superconducting-circuit architectures, indicating that intermediate-scale implementations of blind protocols may become feasible with realistic near-term improvements in gate fidelities.
Abstract In the standard oracle model, an oracle efficiently evaluates an unknown classical function independent of the quantum algorithm itself. Quantum algorithms have a complex interrelationship to their oracles; for example the possibility of quantum speedup is affected by the manner by which oracles are implemented. Therefore, it is physically meaningful to separate oracles from their quantum algorithms, and we introduce one such separation here. We define the blind oracular quantum computation (BOQC) scheme, in which the oracle is a distinct node in a quantum network. Our work augments the client–server setting of quantum computing, in which a powerful quantum computer server is available on the network for discreet use by clients on the network with low quantum power. In BOQC, an oracle is another client that cooperates with the main client so that an oracular quantum algorithm is run on the server. The cooperation between the main client and the oracle takes place (almost) without communication. We prove BOQC to be blind: the server cannot learn anything about the clients’ computation. This proof is performed within the composable security definitions provided by the formalism of abstract cryptography. We enhance the BOQC scheme to be runnable with minimal physical qubits when run on a solid-state quantum network; we prove that this scheme, which we refer to as BOQCo (BOQC-optimized), possesses the same security as BOQC.
hile quantum computers might offer several computational benefits, their application within a quantum network is also of interest in regard to privacy, data protection and computational security. One promising application is blind quantum computing, where a client with limited quantum capacities utilizes the computational power of a quantum computer located at a quantum computing center without revealing any information about the computation or data involved. Several schemes for blind quantum computation have emerged, with the most advanced relying on measurement-based quantum computing [1]. However, many current quantum computer designs are based on gate-based state manipulation. While blind quantum computing is also possible in this scenario, it requires a permanent exchange of quantum information between client and server [2]. To reduce the communication overhead for the involved parties, we study a relaxed scenario of blind quantum computing, where the server gets some information about the algorithm. In particular, we propose a protocol to hide an n-qubit Grover search algorithm by utilizing additional qubits on a quantum server which are initialized by the clients. [1] Fitzsimons, J. F. (2017), npj Quantum Information, 3(1), 23. [2] A. Childs, A. (2005), Quantum Inform. Comput., 5, 456-466.
Blind quantum computation (BQC) allows low-resource clients to securely delegate computations to a quantum server, but server resource costs scale with the computation size, posing a bottleneck for implementations. By leveraging Pauli-based computation (PBC), we achieve BQC with a server whose size depends only on the non-Clifford gate count. Our protocol inherits fault tolerance and qubit virtualization from PBC and reveals that classical-client BQC is possible even in the absence of classical simulability. Finally, we present an entanglement-based dual protocol that performs a resource state computation with a dramatically reduced execution cost.