A key challenge for quantum information science is to realize large-scale, precisely controllable, practical systems for multiparty secure communications. Recently, Guidry etal. [Nat. Photonics16, 52 (2022)10.1038/s41566-021-00901-z] have investigated the quantum optics of a Kerr-based optical frequency comb (OFC), which lays out the way for OFC acting as a quantum resource to realize a low-cost and stable multiparty continuous-variable quantum information processing. In this work, we propose a distributed quantum anonymous voting (DQAV) protocol based on discrete modulated coherent states, in which a Kerr-based OFC serves as the resource to generate multi-frequency quantum signals for multiparty voting. We consider both the single-selection and multiple-selection ballot scenarios, and design the phase compensation method for the OFC-based protocol. Voting security is ensured by the basic laws of quantum mechanics, while voting anonymity is achieved by the random assignment of different frequency sources and the homogeneity of the quantum operations taken on the same voting choice. Numerical analysis calculates the secure voting distance over the thermal-lossy channel, showing the advancement of the proposed protocol under multiparty and multivalued voting tasks.
A key challenge for quantum information science is to realize large-scale, precisely controllable, practical systems for multiparty secure communications. Recently, Guidry etal. [Nat. Photonics16, 52 (2022)10.1038/s41566-021-00901-z] have investigated the quantum optics of a Kerr-based optical frequency comb (OFC), which lays out the way for OFC acting as a quantum resource to realize a low-cost and stable multiparty continuous-variable quantum information processing. In this work, we propose a distributed quantum anonymous voting (DQAV) protocol based on discrete modulated coherent states, in which a Kerr-based OFC serves as the resource to generate multi-frequency quantum signals for multiparty voting. We consider both the single-selection and multiple-selection ballot scenarios, and design the phase compensation method for the OFC-based protocol. Voting security is ensured by the basic laws of quantum mechanics, while voting anonymity is achieved by the random assignment of different frequency sources and the homogeneity of the quantum operations taken on the same voting choice. Numerical analysis calculates the secure voting distance over the thermal-lossy channel, showing the advancement of the proposed protocol under multiparty and multivalued voting tasks.
Classical electronic voting is increasingly being adopted for Internet-based elections, requiring system designs that ensure fairness, legitimacy, verifiability, and voter anonymity-thereby preserving ballot confidentiality, uniqueness, and integrity. Quantum voting can provide information-theoretic security against repudiation and forgery in such systems. However, compared to classical voting protocols, current quantum voting protocols often suffer from limited efficiency, high cost, and implementation complexity. Here, we introduce a streamlined and efficient quantum voting architecture that simplifies the process by eliminating the privacy amplification step in the voting phase while incorporating authority-assisted anonymity, while maintaining full voter authentication, voting, and tallying capabilities. In an experimental demonstration of a quantum voting network, two voters achieved authentication rates of 336 and 406 times per second over 50 km of single-mode fiber, and signed voting files of 25.02 kbit and 56.29 kbit at a quantum signing rate of 966 times per second, resulting in total voting rates of 244 and 279 times per second, respectively. This work represents the first experimental implementation of a continuous-variable (CV)-based quantum anonymous voting prototype. The architecture is designed to be compatible with existing coherent optical communication networks and provides a practical quantum-enhanced building block toward future voting systems.
We investigate the design of anonymous voting protocols, CV-based binary-valued ballot and CV-based multi-valued ballot with continuous variables (CV) in a multi-dimensional quantum cryptosystem to ensure the security of voting procedure and data privacy. The quantum entangled states are employed in the continuous variable quantum system to carry the voting information and assist information transmission, which takes the advantage of the GHZ-like states in terms of improving the utilization of quantum states by decreasing the number of required quantum states. It provides a potential approach to achieve the efficient quantum anonymous voting with high transmission security, especially in large-scale votes.
Self-tallying quantum anonymous voting (SQAV) has drawn considerable attention since it was proposed. However, constrained by design challenges, all existing protocols only accommodate single-selection voting and cannot support multi-selection voting. In this paper, we propose a SQAV protocol with multi-selection voting functionality. In our protocol, nmn-particle entangled states are equally divided into n groups, and the n particles in each entangled state are delivered to n voters, one particle per voter. Each voter obtains n voting vectors by sequentially measuring all his (or her) particles that belong to n different group, and then encodes his or her voting information into the vector corresponding to the secret index. Due to entanglement correlation, each voter can verify whether his or her ballot is correct through computation, while any participant can obtain the vote count for each candidate through computation. Our protocol satisfies self-tallying, nonreusability, verifiability, and fairness.
We introduce a quantum voting protocol that uses superposition and entanglement to enable anonymous voting with trusted voting machines, in a centralized setting with a single machine and in a distributed setting where several machines are linked to a voting center through quantum channels. A voter selects a candidate through a restricted ballot interface; the machine encodes the vote as a phase-flip operation, controlled by the voter's identity register, on an entangled candidate state. Tallying is performed by interference with a reference branch followed by a measurement of the candidate register, which reproduces the vote distribution without iterative classical counting. Because every tallying run consumes the quantum state, the machines store the cast choices classically and replay the voting stage for each run. The protocol uses only basic quantum gates (Hadamard and controlled-Z). We provide analytical examples (4 voters with 2 candidates and 8 voters with 3 candidates) and numerical experiments that simulate ideal conditions, depolarizing, memory, readout, and gate noise, faulty or mistaken ballots, larger instances with confidence intervals, and sampling convergence. The simulations reproduce the theoretical tally probabilities in the ideal case and show how the tally is distorted by noise and by faulty ballots; no error correction or mitigation is applied. Voter anonymity is formalized as the indistinguishability of tallying transcripts under vote permutations, and an identity-dephasing step renders the identity register exactly maximally mixed under the stated trust assumptions. The numbers of protocol runs needed for exact tallying and for winner identification are analyzed explicitly.
The exploitation of quantum mechanics has the potential to solve important challenges and \nintroduce novel technologies enabling, among others, powerful computation (which can solve \ncertain problems exponentially faster than classical computers), perfectly secure communications, \nas well as sensing and imaging with precision and resolutions not achievable by classical means. \nIn order to make use of the unique properties of quantum physics, experimental platforms \nthat provide access to, and allow the control of quantum states, need to be developed. In \nparticular, quantum systems composed of multiple parties are required, where each party is in a \ncoherent superposition of states, and where multiples of such parties are in a coherent \nsuperposition with each other (e.g. being entangled). Additionally, in order to make use of such \nentangled quantum systems, it is required that each individual party can be coherently controlled \nand measured. The usability and available quantum resources of the entangled system is related \nto its size, which is proportional to the number of entangled parties, as well as the dimensionality \nof the superposition each party is in. For this reason, there is a imminent demand to achieve, \ninvestigate, and improve the generation and control of large quantum systems, comprised of as \nmany entangled parties as possible, where each party is in an ideally high-dimensional \nsuperposition. \nMany quantum platforms are currently subject to extensive research, such as trapped ions, \nsuperconducting circuits, defect centers in solid-state crystals, mechanical oscillators, and optical \nquantum states (i.e. photons). While all platforms provide distinct advantages (as well as \nchallenges), optical photon states are of particular interest, because they can interact with other \nquantum systems, and can be transmitted over long distances while preserving their quantum \ncoherence without the need for extensive shielding. A large variety of sources for optical \nquantum states has been demonstrated, however most such implementations suffer from high \ncomplexity, ultimately limiting their scalability. Integrated photonics has recently become a \nleading platform for the compact, cost-efficient, and stable generation and processing of optical \nquantum states. However, to date, integrated quantum sources have only been able to generate \nphoton pairs, which operated on single channels, and single polarization modes. Furthermore, in \nthe few realizations of on-chip entanglement, they were limited to two entangled parties, where \neach party was in a two-dimensional superposition. These limitations of current integrated photon sources arise in large part from the concepts currently exploited to generate and control these \nstates. In particular, path-entangled sources are the most commonly used, but increasing the \nquantum state complexity requires a significant, and very challenging, increase in device \ncomplexity. There is therefore an urgent need to develop new concepts that can achieve the onchip \ngeneration of large and complex photon states without increasing source complexity, while \nstill enabling coherent quantum state control and detection. \nIn this work, we aim to address these limitations by making use of multiple frequency and \ntemporal modes within a single spatial waveguide mode (therefore readily compatible with \nstandard optical fibers) of an on-chip microring resonator. This approach is in contrast to more \ncommonly used techniques relying on path entanglement, which exploits multiple spatial modes \nand generates entanglement by means of complex waveguide structures. Working within a single \nspatial mode, we achieve the first demonstration of pure heralded single photons and entangled \nphoton pairs, which are emitted on multiple frequency modes from a single source. We then \ndemonstrate the first generation of multi-photon entangled quantum states on a photonic chip. \nFinally, by making use of the spectral multi-mode nature of optical frequency combs, we achieve \nthe generation of photon pairs in a coherent superposition of multiple frequency modes, \nrepresenting the first generation of high-dimensional entangled states on a photonic chip. \nOur work represents a significant step forward in the generation of complex quantum \nstates on a photonic chip and in a single spatial mode compatible with standard optical fibers. In \naddition, we demonstrated coherent quantum state control and manipulation for all generated \nstates by means of standard telecommunications components, which could in the future be also \nintegrated on single, monolithic chip. Our results indicate that the exploitation of integrated \noptical frequency comb sources for the generation of optical quantum states can provide a \nscalable and practical platform for quantum technologies.
Ensuring security and integrity of elections constitutes an important challenge with wide-ranging societal implications. Classically, security guarantees can be ensured based on computational complexity, which may be challenged by quantum computers. We show that the use of quantum networks can enable information-theoretic security for the desirable aspects of a distributed voting scheme in a resource-efficient manner. In our approach, ballot information is encoded in quantum states that enable an exponential reduction in communication complexity compared to classical communication. In addition, we provide an efficient and secure anonymous queuing protocol based on a distributed secure sum. As a result, our scheme only requires modest quantum memories with size scaling logarithmically with the number of voters. This intrinsic efficiency together with certain noise-robustness of our protocol paves the way for its physical implementation in realistic quantum networks.