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Journal of Physics B Atomic Molecular and Optical Physics

Implementation of a quantum private query using single-photon transistors

Martijn A. Nagtegaal, M. Blaauboer

Published Jan 3, 2019• 0 citations
Publisher

Abstract

Abstract We propose a quantum-mechanical device consisting of transmon qubits connected to single-photon transmission lines that can be used to perform a boolean quantum private query on a database. Using numerical simulations verified by analytical calculations we analyse the dynamics of the query process in the proposed system by calculating the reflection and transmission probabilities of the photons encoding the questions. We show that the proposed device, which consists of experimentally available components, is capable of performing a quantum private query with high reliability and may form the basic building block of a lager-scale private search engine.

DOI
10.1088/1361-6455/aafbc0

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Abstract We propose a quantum-mechanical device consisting of transmon qubits connected to single-photon transmission lines that can be used to perform a boolean quantum private query on a database. Using numerical simulations verified by analytical calculations we analyse the dynamics of the query process in the proposed system by calculating the reflection and transmission probabilities of the photons encoding the questions. We show that the proposed device, which consists of experimentally available components, is capable of performing a quantum private query with high reliability and may form the basic building block of a lager-scale private search engine.
I propose an implementation of the quantum private query protocol as described in an article using a photon to encode a question and reflectionor transmission of the photon as answer options. Each question is represented by a photon in a transmission line with both ends returning to the user, and the answer is represented by reflection or transmission of this photon caused by the single photon transistor as described in another article. By solving the quantum Langevin equations for the 32 × 32-dimensional operators describing the single photon transistor the system is analysed. This analysis shows that the user privacy is maintained when the returning transmission lines are under the user's control. The probabilities for reflection and transmission are calculated to verify the behaviour of the answering mechanism. By using pulse trains instead of numbered lines to represent questions, the scalability of the system could be improved.
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The Quantum Private Query is a quantum cryptographic protocol to recover information from a database, preserving both user and data privacy: the user can test whether someone has retained information on which query was asked, and the database provider can test the quantity of information released. Here we introduce a new variant Quantum Private Query algorithm which admits a simple linear optical implementation: it employs the photon's momentum (or time slot) as address qubits and its polarization as bus qubit. A proof-of-principle experimental realization is implemented.
The quantum private query is a quantum cryptographic protocol to recover information from a database, preserving both user and data privacy: the user can test whether someone has retained information on which query was asked and the database provider can test the amount of information released. Here we discuss a variant of the quantum private query algorithm that admits a simple linear optical implementation: it employs the photon's momentum (or time slot) as address qubits and its polarization as bus qubit. A proof-of-principle experimental realization is implemented.
Abstract Most of the existing Quantum Private Queries (QPQ) protocols provide only single-bit queries service, thus have to be repeated several times when more bits are retrieved. Wei et al.'s scheme for block queries requires a high-dimension quantum key distribution system to sustain, which is still restricted in the laboratory. Here, based on Markus Jakobi et al.'s single-bit QPQ protocol, we propose a multi-bit quantum private query protocol, in which the user can get access to several bits within one single query. We also extend the proposed protocol to block queries, using a binary matrix to guard database security. Analysis in this paper shows that our protocol has better communication complexity, implementability and can achieve a considerable level of security.
We propose an implementation of a quantum router for microwave photons in a superconducting qubit architecture consisting of a transmon qubit, SQUIDs and a nonlinear capacitor. We model and analyze the dynamics of operation of the quantum switch using quantum Langevin equations in a scattering approach and compute the photon reflection and transmission probabilities. For parameters corresponding to up-to-date experimental devices we predict successful operation of the router with probabilities above 94%.