Blind quantum computation (BQC) enables a client without enough quantum power to delegate his quantum computation to a quantum server, while keeping the input data, the algorithm and the result unknown to the server. In the studies of practical BQC protocol, an important problem is how to reduce the quantum requirement of the client. Multi-server BQC protocols have been proposed to solve this problem. We review the double-server and triple-server protocols [Li et al., Phys. Rev. A 89, 040302(R) (2014)], and propose a modified double-server BQC protocol with a trusted center. In our protocol, the servers are allowed to communicate mutually, and the client is completely classical. Furthermore, our double-server protocol can be modified into a single-server protocol by simply combining the two servers. Compared with the triple-server protocol, our double-server and single-server protocols are more simple and the client is not required to have the ability to access quantum channel. So our protocols are more practical when quantum computer is applied in the `cloud' model.Blind quantum computation (BQC) enables a client without enough quantum power to delegate his quantum computation to a quantum server, while keeping the input data, the algorithm and the result unknown to the server. In the studies of practical BQC protocol, an important problem is how to reduce the quantum requirement of the client. Multi-server BQC protocols have been proposed to solve this problem. We review the double-server and triple-server protocols [Li et al., Phys. Rev. A 89, 040302(R) (2014)], and propose a modified double-server BQC protocol with a trusted center. In our protocol, the servers are allowed to communicate mutually, and the client is completely classical. Furthermore, our double-server protocol can be modified into a single-server protocol by simply combining the two servers. Compared with the triple-server protocol, our double-server and single-server protocols are more simple and the client is not required to have the ability to access quantum channel. So our protocols are more practical when quantum computer is applied in the `cloud' model.

arXiv:1508.07778Aug 31, 20151 citation

Multiple-server Flexible Blind Quantum Computation in Networks

Xiaoqin Kong, Qin Li, Chunhui Wu +3 more

International Journal of Theoretical PhysicsFeb 11, 201615 citations

Complexity-Theoretic Limitations on Blind Delegated Quantum Computation

Scott Aaronson, Alexandru Cojocaru, Alexandru Gheorghiu +1 more

Blind delegation protocols allow a client to delegate a computation to a server so that the server learns nothing about the input to the computation apart from its size. For the specific case of quantum computation we know that blind delegation protocols can achieve information-theoretic security. In this paper we prove, provided certain complexity-theoretic conjectures are true, that the power of information-theoretically secure blind delegation protocols for quantum computation (ITS-BQC protocols) is in a number of ways constrained. In the first part of our paper we provide some indication that ITS-BQC protocols for delegating $\sf BQP$ computations in which the client and the server interact only classically are unlikely to exist. We first show that having such a protocol with $O(n^d)$ bits of classical communication implies that $\mathsf{BQP} \subset \mathsf{MA/O(n^d)}$ . We conjecture that this containment is unlikely by providing an oracle relative to which $\mathsf{BQP} \not\subset \mathsf{MA/O(n^d)}$ . We then show that if an ITS-BQC protocol exists with polynomial classical communication and which allows the client to delegate quantum sampling problems, then there exist non-uniform circuits of size $2^{n - \mathsfΩ(n/log(n))}$ , making polynomially-sized queries to an $\sf NP^{NP}$ oracle, for computing the permanent of an $n \times n$ matrix. The second part of our paper concerns ITS-BQC protocols in which the client and the server engage in one round of quantum communication and then exchange polynomially many classical messages. First, we provide a complexity-theoretic upper bound on the types of functions that could be delegated in such a protocol, namely $\mathsf{QCMA/qpoly \cap coQCMA/qpoly}$ . Then, we show that having such a protocol for delegating $\mathsf{NP}$ -hard functions implies $\mathsf{coNP^{NP^{NP}}} \subseteq \mathsf{NP^{NP^{PromiseQMA}}}$ .Blind delegation protocols allow a client to delegate a computation to a server so that the server learns nothing about the input to the computation apart from its size. For the specific case of quantum computation we know that blind delegation protocols can achieve information-theoretic security. In this paper we prove, provided certain complexity-theoretic conjectures are true, that the power of information-theoretically secure blind delegation protocols for quantum computation (ITS-BQC protocols) is in a number of ways constrained. In the first part of our paper we provide some indication that ITS-BQC protocols for delegating $\sf BQP$ computations in which the client and the server interact only classically are unlikely to exist. We first show that having such a protocol with $O(n^d)$ bits of classical communication implies that $\mathsf{BQP} \subset \mathsf{MA/O(n^d)}$. We conjecture that this containment is unlikely by providing an oracle relative to which $\mathsf{BQP} \not\subset \mathsf{MA/O(n^d)}$. We then show that if an ITS-BQC protocol exists with polynomial classical communication and which allows the client to delegate quantum sampling problems, then there exist non-uniform circuits of size $2^{n - \mathsfΩ(n/log(n))}$, making polynomially-sized queries to an $\sf NP^{NP}$ oracle, for computing the permanent of an $n \times n$ matrix. The second part of our paper concerns ITS-BQC protocols in which the client and the server engage in one round of quantum communication and then exchange polynomially many classical messages. First, we provide a complexity-theoretic upper bound on the types of functions that could be delegated in such a protocol, namely $\mathsf{QCMA/qpoly \cap coQCMA/qpoly}$. Then, we show that having such a protocol for delegating $\mathsf{NP}$-hard functions implies $\mathsf{coNP^{NP^{NP}}} \subseteq \mathsf{NP^{NP^{PromiseQMA}}}$.

arXiv:1704.08482Leibniz international proceedings in informaticsApr 27, 20179 citations

Verifiable Multi‐Party Universal Blind Quantum Computing in Distributed Networks

SHAN Ruiting, CHEN Xiubo, Gang Xu +4 more

Blind quantum computing (BQC) ensures that a classical client could delegate complex computing tasks to a remote quantum server safely. In order to detect the dishonest behavior of the participants, we present a verifiable multi-party universal BQC protocol in distributed networks. By using the stabilizer formalism, we propose an honesty check method to test the correctness of the graph states generated by the servers. The honesty of both the clients and the servers can be judged fairly with the help of the arbitrator. Moreover, a load balancer is introduced to control the possible breakdown of servers in the network. No-signaling principle ensures the unconditional security of the protocol. Through the use of universal resource states, our protocol can be applied in more multi-party verifiable universal BQC protocols. The failure management and workload balancing of the protocol also provide a promising prospect for the future BQC network.Blind quantum computing (BQC) ensures that a classical client could delegate complex computing tasks to a remote quantum server safely. In order to detect the dishonest behavior of the participants, we present a verifiable multi-party universal BQC protocol in distributed networks. By using the stabilizer formalism, we propose an honesty check method to test the correctness of the graph states generated by the servers. The honesty of both the clients and the servers can be judged fairly with the help of the arbitrator. Moreover, a load balancer is introduced to control the possible breakdown of servers in the network. No-signaling principle ensures the unconditional security of the protocol. Through the use of universal resource states, our protocol can be applied in more multi-party verifiable universal BQC protocols. The failure management and workload balancing of the protocol also provide a promising prospect for the future BQC network.

Chinese Journal of ElectronicsJul 1, 20213 citations

\sf BQP

computations in which the client and the server interact only classically are unlikely to exist. We first show that having such a protocol with

O(n^d)

bits of classical communication implies that

\mathsf{BQP} \subset \mathsf{MA/O(n^d)}

. We conjecture that this containment is unlikely by providing an oracle relative to which

\mathsf{BQP} \not\subset \mathsf{MA/O(n^d)}

. We then show that if an ITS-BQC protocol exists with polynomial classical communication and which allows the client to delegate quantum sampling problems, then there exist non-uniform circuits of size

2^{n - \mathsfΩ(n/log(n))}

, making polynomially-sized queries to an

\sf NP^{NP}

oracle, for computing the permanent of an

n \times n

matrix. The second part of our paper concerns ITS-BQC protocols in which the client and the server engage in one round of quantum communication and then exchange polynomially many classical messages. First, we provide a complexity-theoretic upper bound on the types of functions that could be delegated in such a protocol, namely

\mathsf{QCMA/qpoly \cap coQCMA/qpoly}

. Then, we show that having such a protocol for delegating

\mathsf{NP}

-hard functions implies

\mathsf{coNP^{NP^{NP}}} \subseteq \mathsf{NP^{NP^{PromiseQMA}}}