Pub Date : 2025-08-06DOI: 10.1109/TQE.2025.3596491
Haley A. Weinstein;Bruno Avritzer;Christine M. Kinzfogl;Todd A. Brun;Jonathan L. Habif
Quantum steganography is a powerful method for information security where communication between a sender and receiver is disguised as naturally occurring noise in a channel. A candidate resource state required for implementing quantum steganography is a weak coherent state engineered with modulated phase and amplitude values drawn from probability distributions that result in a mixed state indistinguishable from a thermal state. We experimentally demonstrate the construction of this resource state by encoding the phase and amplitude of weak coherent laser states such that a third party monitoring the communication channel, measuring the flow of optical states through the channel, would see an amalgamation of states indistinguishable from thermal noise light such as that from spontaneous emission. Using quantum state tomography, we experimentally reconstructed the density matrices for the artificially engineered thermal states and spontaneous emission from an optical amplifier and verified a mean state fidelity $F=0.98$ when compared with theoretical thermal states.
{"title":"High-Fidelity Artificial Quantum Thermal State Generation Using Encoded Coherent States","authors":"Haley A. Weinstein;Bruno Avritzer;Christine M. Kinzfogl;Todd A. Brun;Jonathan L. Habif","doi":"10.1109/TQE.2025.3596491","DOIUrl":"https://doi.org/10.1109/TQE.2025.3596491","url":null,"abstract":"Quantum steganography is a powerful method for information security where communication between a sender and receiver is disguised as naturally occurring noise in a channel. A candidate resource state required for implementing quantum steganography is a weak coherent state engineered with modulated phase and amplitude values drawn from probability distributions that result in a mixed state indistinguishable from a thermal state. We experimentally demonstrate the construction of this resource state by encoding the phase and amplitude of weak coherent laser states such that a third party monitoring the communication channel, measuring the flow of optical states through the channel, would see an amalgamation of states indistinguishable from thermal noise light such as that from spontaneous emission. Using quantum state tomography, we experimentally reconstructed the density matrices for the artificially engineered thermal states and spontaneous emission from an optical amplifier and verified a mean state fidelity <inline-formula><tex-math>$F=0.98$</tex-math></inline-formula> when compared with theoretical thermal states.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"6 ","pages":"1-7"},"PeriodicalIF":4.6,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11118288","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145036671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-05DOI: 10.1109/TQE.2025.3595910
Shintaro Fujiwara;Naoki Ishikawa
This article presents a novel approach to Grover adaptive search (GAS) for a combinatorial optimization problem whose objective function involves spin variables. While the GAS algorithm with a conventional design of a quantum dictionary subroutine handles a problem associated with an objective function with binary variables $lbrace 0,1rbrace$, we reformulate the problem using spin variables $lbrace +1,-1rbrace$ to simplify the algorithm. Specifically, we introduce a novel quantum dictionary subroutine that is designed for this spin-based formulation. A key benefit of this approach is the substantial reduction in the number of cnot gates required to construct the quantum circuit. We theoretically demonstrate, for certain problems, that our proposed approach can reduce the gate complexity from an exponential order to a polynomial order, compared to the conventional binary-based approach. This improvement has the potential to enhance the scalability and efficiency of GAS, particularly in larger quantum computations.
{"title":"Grover Adaptive Search With Spin Variables","authors":"Shintaro Fujiwara;Naoki Ishikawa","doi":"10.1109/TQE.2025.3595910","DOIUrl":"https://doi.org/10.1109/TQE.2025.3595910","url":null,"abstract":"This article presents a novel approach to Grover adaptive search (GAS) for a combinatorial optimization problem whose objective function involves spin variables. While the GAS algorithm with a conventional design of a quantum dictionary subroutine handles a problem associated with an objective function with binary variables <inline-formula><tex-math>$lbrace 0,1rbrace$</tex-math></inline-formula>, we reformulate the problem using spin variables <inline-formula><tex-math>$lbrace +1,-1rbrace$</tex-math></inline-formula> to simplify the algorithm. Specifically, we introduce a novel quantum dictionary subroutine that is designed for this spin-based formulation. A key benefit of this approach is the substantial reduction in the number of <sc>cnot</small> gates required to construct the quantum circuit. We theoretically demonstrate, for certain problems, that our proposed approach can reduce the gate complexity from an exponential order to a polynomial order, compared to the conventional binary-based approach. This improvement has the potential to enhance the scalability and efficiency of GAS, particularly in larger quantum computations.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"6 ","pages":"1-13"},"PeriodicalIF":4.6,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11113358","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144990176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-04DOI: 10.1109/TQE.2025.3595778
Diogo Cruz;Francisco A. Monteiro;André Roque;Bruno C. Coutinho
This work addresses the open question of implementing fault-tolerant quantum random linear codes (QRLCs) with feasible computational overhead. We present a new decoder for QRLCs capable of dealing with imperfect decoding operations. A first approach, introduced by Cruz et al. (2023), only considered channel errors and perfect gates at the decoder. Here, we analyze the fault-tolerant characteristics of QRLCs with a new noise guessing decoding technique, when considering preparation, measurement, and gate errors in the syndrome extraction procedure, while also accounting for error degeneracy. Our findings indicate a threshold error rate (${p_{text{threshold}}}$) of approximately ${2times 10^{-5}}$ in the asymptotic limit, while considering realistic noise levels in the mentioned physical procedures.
{"title":"Fault-Tolerant Noise Guessing Decoding of Quantum Random Codes","authors":"Diogo Cruz;Francisco A. Monteiro;André Roque;Bruno C. Coutinho","doi":"10.1109/TQE.2025.3595778","DOIUrl":"https://doi.org/10.1109/TQE.2025.3595778","url":null,"abstract":"This work addresses the open question of implementing fault-tolerant quantum random linear codes (QRLCs) with feasible computational overhead. We present a new decoder for QRLCs capable of dealing with imperfect decoding operations. A first approach, introduced by Cruz et al. (2023), only considered channel errors and perfect gates at the decoder. Here, we analyze the fault-tolerant characteristics of QRLCs with a new noise guessing decoding technique, when considering preparation, measurement, and gate errors in the syndrome extraction procedure, while also accounting for error degeneracy. Our findings indicate a threshold error rate (<inline-formula><tex-math>${p_{text{threshold}}}$</tex-math></inline-formula>) of approximately <inline-formula><tex-math>${2times 10^{-5}}$</tex-math></inline-formula> in the asymptotic limit, while considering realistic noise levels in the mentioned physical procedures.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"6 ","pages":"1-26"},"PeriodicalIF":4.6,"publicationDate":"2025-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11112727","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144934470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-04DOI: 10.1109/TQE.2025.3595703
Alberto Tarable;Rudi Paolo Paganelli;Elisabetta Storelli;Alberto Gatto;Marco Ferrari
This article introduces generalized quantum-assisted digital signature (GQaDS), an improved version of a recently proposed scheme whose information-theoretic security is inherited by adopting quantum key distribution keys for digital signature purposes. Its security against forging is computed considering a trial-and-error approach taken by the malicious forger, and GQaDS parameters are optimized via an analytical approach balancing between forgery and repudiation probabilities. The hash functions of the previous implementation are replaced with Carter–Wegman message authentication codes, strengthening the scheme security and reducing the signature length. For particular scenarios where the second verifier has a safe reputation, a simplified version of GQaDS, namely deterministic GQaDS, can further reduce the required signature length, keeping the desired security strength.
{"title":"Generalized Quantum-Assisted Digital Signature","authors":"Alberto Tarable;Rudi Paolo Paganelli;Elisabetta Storelli;Alberto Gatto;Marco Ferrari","doi":"10.1109/TQE.2025.3595703","DOIUrl":"https://doi.org/10.1109/TQE.2025.3595703","url":null,"abstract":"This article introduces generalized quantum-assisted digital signature (GQaDS), an improved version of a recently proposed scheme whose information-theoretic security is inherited by adopting quantum key distribution keys for digital signature purposes. Its security against forging is computed considering a trial-and-error approach taken by the malicious forger, and GQaDS parameters are optimized via an analytical approach balancing between forgery and repudiation probabilities. The hash functions of the previous implementation are replaced with Carter–Wegman message authentication codes, strengthening the scheme security and reducing the signature length. For particular scenarios where the second verifier has a safe reputation, a simplified version of GQaDS, namely deterministic GQaDS, can further reduce the required signature length, keeping the desired security strength.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"6 ","pages":"1-11"},"PeriodicalIF":4.6,"publicationDate":"2025-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11112620","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144909409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Precise time synchronization is a fundamental challenge in distributed quantum systems, with direct implications for secure communication, quantum sensing, and next-generation quantum network technologies. In this work, we present an field programmable gate arrays (FPGA)-based implementation of a synchronization system using time-correlated entangled photons (TCEP), achieving timing precision below 200 ps across 10- and 20-km deployed fiber links using spectral filtering (SF) and dispersion compensation. The system exploits the intrinsic temporal correlations of entangled photon pairs to estimate synchronization offsets between remote nodes. A modular architecture is developed, featuring optimized OpenCL kernels for real-time correlation, timestamp aggregation, and peak normalization. This enables high-throughput performance with efficient utilization of hardware resources. Experimental validation confirms that the FPGA processes entangled photon timestamps and computes cross-correlation functions significantly faster than conventional CPU-based methods, achieving execution times in the range of a few milliseconds for datasets containing up to $10^{5}$ timestamped events per node. Resource utilization analysis further demonstrates the scalability of the design, with the system operating reliably at a 397.5-MHz clock frequency while maintaining efficient logic, register, and memory usage. Our results illustrate the feasibility of deploying FPGA-based TCEP synchronization in real-world quantum networks, supporting applications in ultra-reliable low-latency communication, distributed quantum computing, and quantum-enhanced localization and sensing. This work bridges foundational quantum photonic principles and hardware-level deployment, laying the groundwork for timing infrastructure in future quantum internet and 6G networks.
{"title":"TCEP-Based Synchronization for Practical Communication Network","authors":"Swaraj Shekhar Nande;Shubh Agarwal;Stefan Krause;Riccardo Bassoli;Kay-Uwe Giering;Koteswararao Kondepu;Frank H.P. Fitzek","doi":"10.1109/TQE.2025.3595706","DOIUrl":"https://doi.org/10.1109/TQE.2025.3595706","url":null,"abstract":"Precise time synchronization is a fundamental challenge in distributed quantum systems, with direct implications for secure communication, quantum sensing, and next-generation quantum network technologies. In this work, we present an field programmable gate arrays (FPGA)-based implementation of a synchronization system using time-correlated entangled photons (TCEP), achieving timing precision below 200 ps across 10- and 20-km deployed fiber links using spectral filtering (SF) and dispersion compensation. The system exploits the intrinsic temporal correlations of entangled photon pairs to estimate synchronization offsets between remote nodes. A modular architecture is developed, featuring optimized OpenCL kernels for real-time correlation, timestamp aggregation, and peak normalization. This enables high-throughput performance with efficient utilization of hardware resources. Experimental validation confirms that the FPGA processes entangled photon timestamps and computes cross-correlation functions significantly faster than conventional CPU-based methods, achieving execution times in the range of a few milliseconds for datasets containing up to <inline-formula><tex-math>$10^{5}$</tex-math></inline-formula> timestamped events per node. Resource utilization analysis further demonstrates the scalability of the design, with the system operating reliably at a 397.5-MHz clock frequency while maintaining efficient logic, register, and memory usage. Our results illustrate the feasibility of deploying FPGA-based TCEP synchronization in real-world quantum networks, supporting applications in ultra-reliable low-latency communication, distributed quantum computing, and quantum-enhanced localization and sensing. This work bridges foundational quantum photonic principles and hardware-level deployment, laying the groundwork for timing infrastructure in future quantum internet and 6G networks.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"6 ","pages":"1-12"},"PeriodicalIF":4.6,"publicationDate":"2025-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11112616","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144990175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-04DOI: 10.1109/TQE.2025.3595275
Marco Venere;Alessandro Barenghi;Gerardo Pelosi
The Boolean matching problem via NP-equivalence requires determining whether two Boolean functions are equivalent or not up to a permutation and negation of the input binary variables. Its solution is a fundamental step in the electronic design automation (EDA) tool chains commonly used for digital circuit design. In fact, the library-mapping step of an EDA workflow requires matching parts of the gate-level design (netlist) with the components available in a technology library, considering them as Boolean functions, while taking into account that permutations and negations of input variables can be efficiently implemented through rewiring and the use of inverters. For $n$-to-$n$ vector Boolean functions, where $n$ is the number of input and output variables, the search space of possible negations and permutations is super-exponential in size, while the $mathcal {O}(n!n2^{2n})$ time complexity of classical approaches allows solving only small instances of the NP-problem, often limited to $n$-to-1 Boolean functions (executing $mathcal {O}(n!2^{2n})$ bit operations). This work presents a quantum algorithm for matching $n$-to-$n$ vector Boolean functions by effectively combining the Grover-meets-Simon approach with an original and novel use of the Simon solver without the constraints imposed by its usual premises. We provide a fully detailed quantum circuit implementing our proposal, calculate its cost by evaluating key performance indicators for circuit synthesis, and show an exponential speedup over classical solutions. Finally, we validate our approach on the Boolean functions included in the ISCAS benchmark suite, which are of practical interest in EDA.
{"title":"A Grover-Meets-Simon Approach to Match Vector Boolean Functions","authors":"Marco Venere;Alessandro Barenghi;Gerardo Pelosi","doi":"10.1109/TQE.2025.3595275","DOIUrl":"https://doi.org/10.1109/TQE.2025.3595275","url":null,"abstract":"The Boolean matching problem via NP-equivalence requires determining whether two Boolean functions are equivalent or not up to a permutation and negation of the input binary variables. Its solution is a fundamental step in the electronic design automation (EDA) tool chains commonly used for digital circuit design. In fact, the <italic>library-mapping</i> step of an EDA workflow requires matching parts of the gate-level design (<italic>netlist</i>) with the components available in a technology library, considering them as Boolean functions, while taking into account that permutations and negations of input variables can be efficiently implemented through rewiring and the use of inverters. For <inline-formula><tex-math>$n$</tex-math></inline-formula>-to-<inline-formula><tex-math>$n$</tex-math></inline-formula> vector Boolean functions, where <inline-formula><tex-math>$n$</tex-math></inline-formula> is the number of input and output variables, the search space of possible negations and permutations is super-exponential in size, while the <inline-formula><tex-math>$mathcal {O}(n!n2^{2n})$</tex-math></inline-formula> time complexity of classical approaches allows solving only small instances of the NP-problem, often limited to <inline-formula><tex-math>$n$</tex-math></inline-formula>-to-1 Boolean functions (executing <inline-formula><tex-math>$mathcal {O}(n!2^{2n})$</tex-math></inline-formula> bit operations). This work presents a quantum algorithm for matching <inline-formula><tex-math>$n$</tex-math></inline-formula>-to-<inline-formula><tex-math>$n$</tex-math></inline-formula> vector Boolean functions by effectively combining the Grover-meets-Simon approach with an original and novel use of the Simon solver without the constraints imposed by its usual premises. We provide a fully detailed quantum circuit implementing our proposal, calculate its cost by evaluating key performance indicators for circuit synthesis, and show an exponential speedup over classical solutions. Finally, we validate our approach on the Boolean functions included in the ISCAS benchmark suite, which are of practical interest in EDA.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"6 ","pages":"1-14"},"PeriodicalIF":4.6,"publicationDate":"2025-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11108706","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144896761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The discrete logarithm problem (DLP) over finite fields, commonly used in classical cryptography, has no known polynomial-time algorithm on classical computers. However, Shor has provided its polynomial-time algorithm on quantum computers. Nevertheless, there are only few examples simulating quantum circuits that operate on general pairs of modulo $p$ and order $q$. In this article, we constructed such quantum circuits and solved DLPs for all 1860 possible pairs of $p$ and $q$ up to 32 qubits using a quantum simulator with PRIMEHPC FX700. From this, we obtained and verified values of the success probabilities, which had previously been heuristically analyzed by Ekerå (2019). As a result, the detailed waveform shape of the success probability of Shor's algorithm for solving the DLP, known as a periodic function of order $q$, was clarified. In addition, we generated 1015 quantum circuits for larger pairs of $p$ and $q$, extrapolated the circuit sizes obtained, and compared them for $p=2048$ bits between safe-prime groups and Schnorr groups. While in classical cryptography, the cipher strength of safe-prime groups and Schnorr groups is the same if $p$ is equal, we quantitatively demonstrated how much the strength of the latter decreases to the bit length of $p$ in the former when using Shor's quantum algorithm. In particular, it was experimentally and theoretically shown that when a basic adder is used in the addition circuit, the cryptographic strength of a Schnorr group with $p=2048$ bits under Shor's algorithm is almost equivalent to that of a safe-prime group with $p=1024$ bits.
{"title":"Simulation of Shor Algorithm for Discrete Logarithm Problems With Comprehensive Pairs of Modulo $p$ and Order $q$","authors":"Kaito Kishi;Junpei Yamaguchi;Tetsuya Izu;Noboru Kunihiro","doi":"10.1109/TQE.2025.3591213","DOIUrl":"https://doi.org/10.1109/TQE.2025.3591213","url":null,"abstract":"The discrete logarithm problem (DLP) over finite fields, commonly used in classical cryptography, has no known polynomial-time algorithm on classical computers. However, Shor has provided its polynomial-time algorithm on quantum computers. Nevertheless, there are only few examples simulating quantum circuits that operate on general pairs of modulo <inline-formula><tex-math>$p$</tex-math></inline-formula> and order <inline-formula><tex-math>$q$</tex-math></inline-formula>. In this article, we constructed such quantum circuits and solved DLPs for all 1860 possible pairs of <inline-formula><tex-math>$p$</tex-math></inline-formula> and <inline-formula><tex-math>$q$</tex-math></inline-formula> up to 32 qubits using a quantum simulator with PRIMEHPC FX700. From this, we obtained and verified values of the success probabilities, which had previously been heuristically analyzed by Ekerå (2019). As a result, the detailed waveform shape of the success probability of Shor's algorithm for solving the DLP, known as a periodic function of order <inline-formula><tex-math>$q$</tex-math></inline-formula>, was clarified. In addition, we generated 1015 quantum circuits for larger pairs of <inline-formula><tex-math>$p$</tex-math></inline-formula> and <inline-formula><tex-math>$q$</tex-math></inline-formula>, extrapolated the circuit sizes obtained, and compared them for <inline-formula><tex-math>$p=2048$</tex-math></inline-formula> bits between safe-prime groups and Schnorr groups. While in classical cryptography, the cipher strength of safe-prime groups and Schnorr groups is the same if <inline-formula><tex-math>$p$</tex-math></inline-formula> is equal, we quantitatively demonstrated how much the strength of the latter decreases to the bit length of <inline-formula><tex-math>$p$</tex-math></inline-formula> in the former when using Shor's quantum algorithm. In particular, it was experimentally and theoretically shown that when a basic adder is used in the addition circuit, the cryptographic strength of a Schnorr group with <inline-formula><tex-math>$p=2048$</tex-math></inline-formula> bits under Shor's algorithm is almost equivalent to that of a safe-prime group with <inline-formula><tex-math>$p=1024$</tex-math></inline-formula> bits.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"6 ","pages":"1-12"},"PeriodicalIF":4.6,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11087664","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144896789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-14DOI: 10.1109/TQE.2025.3588783
Evan Sutcliffe;Alejandra Beghelli
We consider the problem of distributing entangled multipartite states across a quantum network with improved distribution rate and fidelity. For this, we propose fidelity-aware multipath routing protocols, assess their performance in terms of the rate and fidelity of the distributed Greenberger–Horne–Zeilinger (GHZ) states, and compare such performance against that of single-path routing. Simulation results show that the proposed multipath routing protocols select routes that require more Bell states compared to single-path routing, but also require fewer rounds of Bell state generation. We also optimized the tradeoff between distribution rate and fidelity by selecting an appropriate cutoff to the quantum memory storage time. Using such a cutoff technique, the proposed multipath protocols can achieve up to an 8.3 times higher distribution rate and up to a 28% improvement in GHZ state fidelity compared to single-path routing. These results show that multipath routing both improves the distribution rates and enhances fidelity for multipartite state distribution.
{"title":"Fidelity-Aware Multipath Routing for Multipartite State Distribution in Quantum Networks","authors":"Evan Sutcliffe;Alejandra Beghelli","doi":"10.1109/TQE.2025.3588783","DOIUrl":"https://doi.org/10.1109/TQE.2025.3588783","url":null,"abstract":"We consider the problem of distributing entangled multipartite states across a quantum network with improved distribution rate and fidelity. For this, we propose fidelity-aware multipath routing protocols, assess their performance in terms of the rate and fidelity of the distributed Greenberger–Horne–Zeilinger (GHZ) states, and compare such performance against that of single-path routing. Simulation results show that the proposed multipath routing protocols select routes that require more Bell states compared to single-path routing, but also require fewer rounds of Bell state generation. We also optimized the tradeoff between distribution rate and fidelity by selecting an appropriate cutoff to the quantum memory storage time. Using such a cutoff technique, the proposed multipath protocols can achieve up to an 8.3 times higher distribution rate and up to a 28% improvement in GHZ state fidelity compared to single-path routing. These results show that multipath routing both improves the distribution rates and enhances fidelity for multipartite state distribution.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"6 ","pages":"1-18"},"PeriodicalIF":4.6,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11079232","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144750969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-07DOI: 10.1109/TQE.2025.3586541
Michael Garn;Angus Kan
We perform logical and physical resource estimation for computing binary elliptic curve discrete logarithms using Shor's algorithm on fault-tolerant quantum computers. We adopt a windowed approach to design our circuit implementation of the algorithm, which comprises repeated applications of elliptic curve point addition operations and table look-ups. Unlike previous work, the point addition operation is implemented exactly, including all exceptional cases. We provide exact logical gate and qubit counts of our algorithm for cryptographically relevant binary field sizes. Furthermore, we estimate the hardware footprint and runtime of our algorithm executed on surface-code matter-based quantum computers with a baseline architecture, where logical qubits have nearest-neighbor connectivity, and on a surface-code photonic fusion-based quantum computer with an active-volume architecture, which enjoys a logarithmic number of nonlocal connections between logical qubits. At 10$%$ threshold and compared to a baseline device with a 1-$mu text{s}$ code cycle, our algorithm runs $gtrsim$ 2–20 times faster, depending on the operating regime of the hardware and over all considered field sizes, on a photonic active-volume device.
{"title":"Quantum Resource Estimates for Computing Binary Elliptic Curve Discrete Logarithms","authors":"Michael Garn;Angus Kan","doi":"10.1109/TQE.2025.3586541","DOIUrl":"https://doi.org/10.1109/TQE.2025.3586541","url":null,"abstract":"We perform logical and physical resource estimation for computing binary elliptic curve discrete logarithms using Shor's algorithm on fault-tolerant quantum computers. We adopt a windowed approach to design our circuit implementation of the algorithm, which comprises repeated applications of elliptic curve point addition operations and table look-ups. Unlike previous work, the point addition operation is implemented exactly, including all exceptional cases. We provide exact logical gate and qubit counts of our algorithm for cryptographically relevant binary field sizes. Furthermore, we estimate the hardware footprint and runtime of our algorithm executed on surface-code matter-based quantum computers with a baseline architecture, where logical qubits have nearest-neighbor connectivity, and on a surface-code photonic fusion-based quantum computer with an active-volume architecture, which enjoys a logarithmic number of nonlocal connections between logical qubits. At 10<inline-formula><tex-math>$%$</tex-math></inline-formula> threshold and compared to a baseline device with a 1-<inline-formula><tex-math>$mu text{s}$</tex-math></inline-formula> code cycle, our algorithm runs <inline-formula><tex-math>$gtrsim$</tex-math></inline-formula> 2–20 times faster, depending on the operating regime of the hardware and over all considered field sizes, on a photonic active-volume device.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"6 ","pages":"1-23"},"PeriodicalIF":4.6,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11072281","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144914382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-26DOI: 10.1109/TQE.2025.3583570
Laura Di Marino;Luigi Di Palma;Michele Riccio;Francesco Fienga;Marco Arzeo;Oleg Mukhanov
Quantum computation requires high-fidelity qubit readout, preserving the quantum state. In the case of superconductings qubits, readout is typically performed using a complex analog experimental setup operating at room temperature, which poses significant technological and economic barriers to large system scalability. An alternative approach is to perform a cryogenic on-chip qubit readout based on a Josephson digital phase detector (JDPD): a flux switchable device capable of digitizing the phase sign of a coherent input. The readout operation includes the flux excitation of the JDPD to evolve from a single- to a double-minima potential. In this work, the effect of the flux bias characteristics on the JDPD performances is studied numerically. To meet the identified requirements that maximize detection fidelity and tackle the engineering challenges, a cryogenic on-chip single flux quantum-based flux bias driver is proposed and discussed.
{"title":"Control of a Josephson Digital Phase Detector via an SFQ-Based Flux Bias Driver","authors":"Laura Di Marino;Luigi Di Palma;Michele Riccio;Francesco Fienga;Marco Arzeo;Oleg Mukhanov","doi":"10.1109/TQE.2025.3583570","DOIUrl":"https://doi.org/10.1109/TQE.2025.3583570","url":null,"abstract":"Quantum computation requires high-fidelity qubit readout, preserving the quantum state. In the case of superconductings qubits, readout is typically performed using a complex analog experimental setup operating at room temperature, which poses significant technological and economic barriers to large system scalability. An alternative approach is to perform a cryogenic on-chip qubit readout based on a Josephson digital phase detector (JDPD): a flux switchable device capable of digitizing the phase sign of a coherent input. The readout operation includes the flux excitation of the JDPD to evolve from a single- to a double-minima potential. In this work, the effect of the flux bias characteristics on the JDPD performances is studied numerically. To meet the identified requirements that maximize detection fidelity and tackle the engineering challenges, a cryogenic on-chip single flux quantum-based flux bias driver is proposed and discussed.","PeriodicalId":100644,"journal":{"name":"IEEE Transactions on Quantum Engineering","volume":"6 ","pages":"1-8"},"PeriodicalIF":4.6,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11052858","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144781922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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