Blind oracular quantum computation : from concept to physical implementation

Gustiani, Cica; DiVincenzo, David (Thesis advisor); Hassler, Fabian (Thesis advisor)

Aachen : RWTH Aachen University (2020, 2021)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2020

Abstract

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.