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Enhanced security in Quantum Token protocols using Hybrid Spin-Photon Interfaces

Durga Bhaktavatsala Rao Dasari, Yang Wang, Jörg Wrachtrup

TL;DR

It is shown here that the three stages of the Quantum token protocols involving the preparation, storage and verification can be made more secure when involving spin-photon interfaces that leverage high fidelity hybrid tripartite (spin-photon-spin) entanglement, Bell state measurements and highly coherent spin quantum memories.

Abstract

Quantum token protocols enable unforgeable quantum tokens promising unconditional security beyond classical cryptographic assumptions. We show here that the three stages of the Quantum token protocols involving the preparation, storage and verification can be made more secure when involving spin-photon interfaces that leverage high fidelity hybrid tripartite (spin-photon-spin) entanglement, Bell state measurements and highly coherent spin quantum memories. Further we describe the physical implementation of various stages of the protocol using the hybrid electron and nuclear spins in diamond interfaced with time-bin photons.

Enhanced security in Quantum Token protocols using Hybrid Spin-Photon Interfaces

TL;DR

It is shown here that the three stages of the Quantum token protocols involving the preparation, storage and verification can be made more secure when involving spin-photon interfaces that leverage high fidelity hybrid tripartite (spin-photon-spin) entanglement, Bell state measurements and highly coherent spin quantum memories.

Abstract

Quantum token protocols enable unforgeable quantum tokens promising unconditional security beyond classical cryptographic assumptions. We show here that the three stages of the Quantum token protocols involving the preparation, storage and verification can be made more secure when involving spin-photon interfaces that leverage high fidelity hybrid tripartite (spin-photon-spin) entanglement, Bell state measurements and highly coherent spin quantum memories. Further we describe the physical implementation of various stages of the protocol using the hybrid electron and nuclear spins in diamond interfaced with time-bin photons.
Paper Structure (3 sections, 22 equations, 2 figures)

This paper contains 3 sections, 22 equations, 2 figures.

Table of Contents

  1. Introduction
  2. Protocol
  3. Physical Implementation

Figures (2)

  • Figure 1: (Left) Schematic displaying the three entitites of the QT protocol, viz., the User, Bank and the Verifier. The user communicates both with the bank and the verifier by sending time-bin photons that are entangled to the ancillay spins of his Hybrid Quantum node. (Right) The Quantum circuit describing all the seven stages of the protocol is shown. The QT issuance storage and verification parts are highlighted in the circuit. From the classical measurement output data one establishes the strong verification conditions i.e., $m2=m1 \oplus (r1 \oplus r2)$.
  • Figure 2: (a) Schematic of the physical system implementing the QT protocol. The NV center electron spin in diamond (yellow arrow) coupled to a nearby nuclear spin (purple arrow) emitting time-bin photons that are respectively phase-shifted ($\varphi$) and detected at $D_{1(2)}$. Both the bank and the verifier use this setup for issuing and verifying their Quantum Tokens. (b) The energy-level diagram showing the states and control invovled in establishing the spin-photon interface. (c) The probiability of verifying the user token by clicks in the verifiers detectors, $VD_{1(2)}$ is plotted as a fucntion of the storage time $T_S$ measured in units of the memory life-time $T_M$.