EPJ Quantum Technology最新文献

{"title":"HAQA: a hardware-guided and fidelity-aware strategy for efficient qubit mapping optimization","authors":"Wenjie Sun,&nbsp;Xiaoyu Li,&nbsp;Lianhui Yu,&nbsp;Zhigang Wang,&nbsp;Geng Chen,&nbsp;Desheng Zheng,&nbsp;Guowu Yang","doi":"10.1140/epjqt/s40507-026-00505-y","DOIUrl":"10.1140/epjqt/s40507-026-00505-y","url":null,"abstract":"<div><p>Quantum compilation bridges the gap between abstract quantum algorithms and physical hardware execution. However, on Noisy Intermediate-Scale Quantum (NISQ) devices, particularly within superconducting architectures, mapping logical circuits to physical qubits remains a fundamental bottleneck due to rigid connectivity constraints and heterogeneous noise profiles. While exact mapping solvers theoretically ensure optimality, they face severe scalability issues on large-scale chips. The search space for global optimization becomes intractable as the system size increases. This scalability barrier largely arises because conventional methods often treat the hardware coupling graph as a homogeneous entity. By performing global searches with weak awareness of physical fidelity distributions, they fail to exploit the hardware’s inherent structural advantages. To address this, we propose HAQA, a hardware-guided strategy that shifts the mapping paradigm from a blind global search to an adaptive, fidelity-aware regional optimization. Specifically, HAQA identifies optimal topological subgraphs through a community-based recursive fusion mechanism. This approach achieves a dual benefit: it reduces solving complexity from exponential to polynomial levels by effectively pruning the search space, while simultaneously enhancing execution fidelity by prioritizing high-quality physical qubits. Experimental evaluations on IBM Eagle and Heron processors demonstrate significant efficiency gains. HAQA accelerates state-of-the-art SMT solvers (QSynth-v2 and TB-OLSQ2) by factors of 632.76× and 286.87×, respectively, while improving fidelity by up to 238.28%. These results suggest that integrating fine-grained physical awareness provides an effective pathway to balance computational complexity and execution quality in quantum compilation, positioning HAQA as a plug-and-play enhancement compatible with various solvers.</p></div>","PeriodicalId":547,"journal":{"name":"EPJ Quantum Technology","volume":"13 1","pages":""},"PeriodicalIF":5.6,"publicationDate":"2026-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjqt/s40507-026-00505-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148173013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cryogenic high-Q passive hanger type drive-line notch filtering for leakage-resilient qubit control","authors":"Seung-Young Seo,&nbsp;Jaehyeong Jo,&nbsp;Jungjae Park,&nbsp;Ji Wan Song,&nbsp;Jiman Choi,&nbsp;Yong-Ho Lee,&nbsp;Kibog Park,&nbsp;Jae-Yoon Sim","doi":"10.1140/epjqt/s40507-026-00508-9","DOIUrl":"10.1140/epjqt/s40507-026-00508-9","url":null,"abstract":"<div><p>Short control pulses broaden spectrally and drive unwanted ∣1<span>(rangle leftrightarrow mid )</span>2〉 transitions in weakly anharmonic qubits. We introduce a passive hardware mitigation: a capacitively coupled quarter-wavelength (<i>λ</i>/4) resonator on the qubit drive line, creating a notch at f₁₂ while leaving f₀₁ largely unaffected. Implemented as a superconducting device at millikelvin temperature, the filter exhibits high Q_L and a sharply localized, low-loss stopband. The coupling capacitance sets Q_c, enabling lithographic tuning of notch depth and linewidth. Simulations and cryogenic S₂₁ measurements confirm a well-defined minimum with minimal off-resonant distortion. Integrated in a qubit setup, the filter suppresses short-pulse leakage: spectroscopy reduces the f₁₂ feature and IQ-plane data show a stable ∣e〉 cluster; at pulse length (<span>(T_{mathrm{p}})</span>) = 6 ns the <span>(f_{12})</span> peak-height ratio drops by ∼7 dB. The approach is fully passive, wiring-free, and scalable, and complements derivative removal by adiabatic gate (DRAG) by allowing shorter envelopes or smaller DRAG weights.</p></div>","PeriodicalId":547,"journal":{"name":"EPJ Quantum Technology","volume":"13 1","pages":""},"PeriodicalIF":5.6,"publicationDate":"2026-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjqt/s40507-026-00508-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148173084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-tasking through quantum annealing","authors":"Jargalsaikhan Artag,&nbsp;Koki Awaya,&nbsp;Takumi Kanezashi,&nbsp;Daisuke Tsukayama,&nbsp;Moe Shimada,&nbsp;Jun-ichi Shirakashi","doi":"10.1140/epjqt/s40507-026-00504-z","DOIUrl":"10.1140/epjqt/s40507-026-00504-z","url":null,"abstract":"<div><p>Quantum annealing approximately solves combinatorial optimization problems by leveraging the principles of adiabatic quantum systems. In this approach, the system’s Hamiltonian evolves from an initial general state to a problem-specific state. This study introduces multi-tasking quantum annealing (MTQA), a method that enables the parallel processing of multiple optimization problems by embedding them into spatially distinct regions on quantum hardware. MTQA is evaluated using two NP-hard problems: the minimum vertex cover problem (MVCP) and the graph partitioning problem (GPP). This parallel approach optimizes quantum resource utilization by concurrently utilizing idle qubits. The findings demonstrate that MTQA achieves a solution quality comparable to single-problem quantum annealing and classical simulated annealing (SA), while notably reducing the time-to-solution (TTS) metrics. Eigenspectrum analysis further theoretically supports the hypothesis that parallel embedding preserves quantum coherence and does not increase computational complexity by efficiently utilizing available quantum hardware (e.g., qubits and couplers). MTQA enables efficient multitasking in quantum annealing, optimizing hardware utilization and improving throughput for concurrent tasks and demonstrating performance for problems up to 100 nodes in real-world applications.</p></div>","PeriodicalId":547,"journal":{"name":"EPJ Quantum Technology","volume":"13 1","pages":""},"PeriodicalIF":5.6,"publicationDate":"2026-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjqt/s40507-026-00504-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148008779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards metaphors for quantum computational thinking","authors":"Caiseal Beardow,&nbsp;Pieter Jan Stappers","doi":"10.1140/epjqt/s40507-026-00502-1","DOIUrl":"10.1140/epjqt/s40507-026-00502-1","url":null,"abstract":"<div><p>In recent years, the quantum computing industry has seen significant investment and growth. However, this burgeoning industry faces a persistent labour gap: individuals with computing expertise, an understanding of quantum principles, and the ability to apply these principles to computing practices, are in increasing demand, but finding such individuals is proving challenging. We frame this problem as one of education, arguing that a computing-centred approach to learning about quantum computing is needed, and that the notion of computational thinking can help to define appropriate learning goals and outcomes in this context. We propose that metaphors can be an effective pedagogical tool in supporting the development of ‘quantum computational thinking’.</p><p>In this paper, we present our efforts to gather and assess a collection of metaphors that are currently used to teach quantum computing concepts. We describe a series of interviews with quantum computing experts in which we aimed to elicit such metaphors, and document our process of metaphor identification and metaphorical model synthesis. We subsequently assess these metaphors and models using both numerical rating data from experts and our own qualitative analysis.</p><p>Informed by our findings, we suggest ways of developing metaphors that better support quantum computational thinking: emphasising target concepts’ computational roles, acknowledging connections between concepts, and balancing procedural narratives with embodied, tangible imagery.</p></div>","PeriodicalId":547,"journal":{"name":"EPJ Quantum Technology","volume":"13 1","pages":""},"PeriodicalIF":5.6,"publicationDate":"2026-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjqt/s40507-026-00502-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147938187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"What makes a good quantum outreach video? An evaluation framework for a quantum video playlist","authors":"Daria Anttila,&nbsp;Philipp Bitzenbauer,&nbsp;Stina Scheer,&nbsp;Diana Tartaglia,&nbsp;Bart Folkers,&nbsp;Simon Goorney,&nbsp;Sohan Vartak,&nbsp;Jacob Sherson,&nbsp;Costanza Toninelli","doi":"10.1140/epjqt/s40507-025-00461-z","DOIUrl":"10.1140/epjqt/s40507-025-00461-z","url":null,"abstract":"<div><p>With increasing applications and industrialization of quantum-based technologies, quantum literacy is becoming progressively important for the general public. Online outreach videos are a popular tool due to their adaptability to complex contents. However, they can contain misinformation and foster inaccurate interpretations of quantum principles. The European Quantum Technology Flagship is addressing this by curating educational materials available to the public. Nevertheless, the community is still lacking an unambiguous method to assess the explanatory quality of quantum videos. Such a development would benefit teachers, science communicators and those who want to foster quantum knowledge outside of specialist endeavors. To close this gap, we iteratively developed an evaluative framework for quantum outreach videos, drawing on existing literature concerning educational videos. Two raters applied the final version of the framework to 20 videos (Cohen’s kappa 0.48). The results showed that some subcategories were coded rarely or not reliably enough, so a condensed version of the framework was introduced (Cohen’s kappa 0.59). We foresee an application of this framework to collections of quantum outreach videos. It illuminates the aspects to consider when creating such videos and highlights the importance of better defining how using certain subcategories can improve the explanatory quality of a video.</p></div>","PeriodicalId":547,"journal":{"name":"EPJ Quantum Technology","volume":"13 1","pages":""},"PeriodicalIF":5.6,"publicationDate":"2026-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjqt/s40507-025-00461-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147606430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DuoQ-EpiNet: a dual-track quantum–classical convolutional neural network for EEG-based epilepsy seizure detection","authors":"Shivanya Shomir Dutta,&nbsp;Ishaan Milind Sawant,&nbsp;Sridevi S,&nbsp;Gurjit S. Randhawa,&nbsp;Rajiv Mistry,&nbsp;Jonathan Ortega,&nbsp;Anandan P,&nbsp;Indira B","doi":"10.1140/epjqt/s40507-026-00500-3","DOIUrl":"10.1140/epjqt/s40507-026-00500-3","url":null,"abstract":"<div><p>Epileptic seizure detection remains a critical challenge in clinical neurodiagnostics, particularly in low-data settings where EEG recordings are scarce. To address this, we propose DuoQ-EpiNet a dual-track hybrid framework that integrates quantum and classical deep learning models for robust seizure classification using the University of Bonn EEG dataset. In the first track, handcrafted statistical and spectral descriptors are extracted from the raw EEG signals and subsequently analyzed using a 1D Convolutional Neural Network (CNN) to learn discriminative temporal representations. In parallel, the second track with wavelet approach transforms the EEG signals into scalogram images, which are processed through a Hybrid Quanvolutional Classical Convolutional Neural Network (HQCNN) equipped with a Fixed Quantum Filter Circuit to generate expressive quantum feature maps followed by classical CNN. The latent representations obtained from both tracks are then fused and passed through fully connected layers to perform the final binary classification. Systematic comparison of the proposed DuoQ-EpiNet model by tweaking quantum hyperparameter based variants, state-of-the-art HQCNN architectures, as well as the best classical transfer learning models have demonstrated that the proposed model performs better than all evaluated variants. Among all evaluated configurations, the proposed DuoQ-EpiNet Binary Dual-Track (P-B-D) model achieved outstanding performance of 98.50% accuracy with its FQFC employed in Track 2 contrived with quantum hyperparameters of <span>(n_{shots} = 1000)</span> and <span>(n_{layers} = 1)</span>. Performance in data-scale studies ranging from 5% to 100% shows that DuoQ-EpiNet outperforms traditional baselines. Its generalization ability is confirmed by evaluation on the CHB-MIT scalp EEG dataset. The model maintains its stability at low noise densities with only slight performance deterioration, according to NISQ robustness study employing density matrix simulations with depolarizing, amplitude damping, phase damping, and readout noise.</p></div>","PeriodicalId":547,"journal":{"name":"EPJ Quantum Technology","volume":"13 1","pages":""},"PeriodicalIF":5.6,"publicationDate":"2026-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjqt/s40507-026-00500-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147607239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing Quantum Key Distribution via McEliece-based hybrid PQC-QKD architecture","authors":"Veeresh R. Maned,&nbsp;Satyabrat Rath,&nbsp;Jothi Ramalingam,&nbsp;Lakshmi Kuppusamy","doi":"10.1140/epjqt/s40507-026-00498-8","DOIUrl":"10.1140/epjqt/s40507-026-00498-8","url":null,"abstract":"<div><p>Quantum Key Distribution (QKD) offers information-theoretic security; however, its practicality is limited by an inherently low secret key rate. In this work, we propose a cryptographic enhancement of QKD by incorporating post-quantum public key encryption, namely Classic McEliece. We propose a novel hybrid PQC-QKD protocol named BBM that employs QC-LDPC based McEliece cryptosystem to encrypt the basis string in QKD, thereby skipping the sifting step and consequently improving the secret key rate. We only need to assume the short-term security of the McEliece cryptosystem during the protocol run to achieve the everlasting security of the distilled keys. Our analysis demonstrates that this integration not only enhances the achievable secret key rate by <span>(sim 2times )</span> in the BB84 protocol but also provides resistance against photon number splitting attack, and inherits a fallback mechanism in its design. This marks a significant improvement in terms of efficiency, security, and reliability over conventional BB84-like QKD protocols.</p></div>","PeriodicalId":547,"journal":{"name":"EPJ Quantum Technology","volume":"13 1","pages":""},"PeriodicalIF":5.6,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjqt/s40507-026-00498-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147560812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modulator-free, self-testing quantum random number generator","authors":"Ana Blázquez-Coído,&nbsp;Fadri Grünenfelder,&nbsp;Anthony Martin,&nbsp;Raphaël Houlmann,&nbsp;Hugo Zbinden,&nbsp;Davide Rusca","doi":"10.1140/epjqt/s40507-026-00501-2","DOIUrl":"10.1140/epjqt/s40507-026-00501-2","url":null,"abstract":"<div><p>Quantum random number generators (QRNGs) use the inherent unpredictability of quantum mechanics to generate true randomness, as opposed to classical random number generators. However, ensuring the authenticity of this randomness still requires robust verification. Self-testing QRNGs address this need by enabling the validation of the randomness produced based on the observed data from the experiment while requiring few assumptions. In this work, we present a practical, self-testing QRNG designed to operate with an untrusted measurement device and a partially characterized source, allowing the user to check the adequate functioning of the setup in real time. Our experiment yields a rate of certified random bits of 450 kbps.</p></div>","PeriodicalId":547,"journal":{"name":"EPJ Quantum Technology","volume":"13 1","pages":""},"PeriodicalIF":5.6,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjqt/s40507-026-00501-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147796928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"BB84 a new hope enhanced QKD for secure email communication with additional quantum gates","authors":"Shiiv R S,&nbsp;Yuven Senthilkumar,&nbsp;V. Karthick","doi":"10.1140/epjqt/s40507-026-00493-z","DOIUrl":"10.1140/epjqt/s40507-026-00493-z","url":null,"abstract":"<div><p>The imminent realization of fault-tolerant quantum computing presents an existential threat to the cryptographic foundations of the modern digital economy. Algorithms such as Shor’s and Grover’s are poised to dismantle classical public-key encryption schemes like RSA (Shor in SIAM Rev. 41:303–332, 1999) and Elliptic Curve Cryptography (ECC) by solving integer factorization and discrete logarithm problems in polynomial time (Grover in A fast quantum mechanical algorithm for database search, 1996, arXiv [quant-ph]). This vulnerability endangers critical infrastructures, particularly secure email correspondence, which remains a primary vector for sensitive data exchange. Traditional defenses are proving inadequate against the “harvest now, decrypt later” strategies employed by sophisticated adversaries who stockpile encrypted traffic in anticipation of Q-Day (Venkatesh et al. in J. Sci. Eng. Technol. Manag. Sci. 2:567–577, 2025). Against this backdrop, this research introduces BB8-4, an enhanced Quantum Key Distribution (QKD) protocol specifically designed for secure email environments. The protocol advances the standard BB84 paradigm through two distinct innovations: the integration of a Hyper-Entropic 7-Gate State Preparation mechanism and an AI-Driven Dynamic Basis Selection engine.</p><p>Unlike traditional implementations that rely on a limited two-basis set, BB8-4 incorporates an expanded library of quantum gates - specifically Identity (I), Hadamard (H), Pauli-X, Pauli-Y, Pauli-Z, Phase (S), and the non-Clifford <span>(pi /8)</span> gate (T) - to fundamentally augment the indistinguishability and Von Neumann entropy of the transmitted quantum states. This “7-gate” approach forces an eavesdropper into a higher-dimensional guessing space, significantly degrading the information gain from intercept-resend attacks and raising the disturbance threshold required for detection. Furthermore, the protocol addresses the inherent 50% sifting inefficiency of standard QKD by employing a synchronized Deep Reinforcement Learning (DRL) agent to predict and align measurement bases between Alice and Bob without public disclosure (Kaldari et al. in Quantum reinforcement learning: Recent advances and future directions, 2025, arXiv [quant-ph]).</p></div>","PeriodicalId":547,"journal":{"name":"EPJ Quantum Technology","volume":"13 1","pages":""},"PeriodicalIF":5.6,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjqt/s40507-026-00493-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147561065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Decoding the surface code with a spatio-temporal transformer","authors":"Robert Joo","doi":"10.1140/epjqt/s40507-026-00492-0","DOIUrl":"10.1140/epjqt/s40507-026-00492-0","url":null,"abstract":"<div><p>Quantum error correction is a major area of research for building fault-tolerant quantum computers. Recently, machine learning has emerged as a compelling approach to quantum error decoding because of its flexibility and high performance compared to classical methods. In this work, we introduce a spatio-temporal transformer with graph Laplacian positional encodings and factorized latent attention to efficiently deal with the topological structure of the code and the temporal correlations across measurement rounds. We perform experiments with simulated data of the surface code for small distances and demonstrate the potential for our model.</p></div>","PeriodicalId":547,"journal":{"name":"EPJ Quantum Technology","volume":"13 1","pages":""},"PeriodicalIF":5.6,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjqt/s40507-026-00492-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147796356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}