Daniele De Bernardis, Hugo Levy-Falk, Elena Fanella, Rocco Duquennoy, Valerio Digiorgio, Giacomo Scalari, Maja Colautti and Costanza Toninelli
{"title":"Hybrid interfaces at the single quantum level in fluorescent molecules","authors":"Daniele De Bernardis, Hugo Levy-Falk, Elena Fanella, Rocco Duquennoy, Valerio Digiorgio, Giacomo Scalari, Maja Colautti and Costanza Toninelli","doi":"10.1088/2058-9565/ae0960","DOIUrl":"https://doi.org/10.1088/2058-9565/ae0960","url":null,"abstract":"We theoretically investigate a single fluorescent molecule as a hybrid quantum optical device, in which multiple external laser sources exert control of the vibronic states. In the high-saturation regime, a coherent interaction is established between the vibrational and electronic degrees of freedom, and molecules can simulate several cavity QED models, whereby a specific vibrational mode plays the role of the cavity mode. Focusing on the specific example where the system is turned into an analogue simulator of the quantum Rabi model, the steady state exhibits vibrational bi-modality resulting in a statistical mixture of highly non-classical vibronic cat states. Applying our paradigm to molecules with prominent spatial asymmetry and combining an optical excitation with a THz(IR) driving, the system can be turned into a single photon transducer. Two possible implementations are discussed based on the coupling to a subwavelength THz patch antenna or a resonant metamaterial. In a nutshell, this work assesses the role of molecules as an optomechanical quantum toolbox for creating hybrid entangled states of electrons, photons, and vibrations, hence enabling frequency conversion over very different energy scales.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"28 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Siting Tang, Francesco Albarelli, Yue Zhang, Shunlong Luo and Matteo G A Paris
{"title":"Quantifying complexity of continuous-variable quantum states via Wehrl entropy and Fisher information","authors":"Siting Tang, Francesco Albarelli, Yue Zhang, Shunlong Luo and Matteo G A Paris","doi":"10.1088/2058-9565/ae08df","DOIUrl":"https://doi.org/10.1088/2058-9565/ae08df","url":null,"abstract":"The notion of complexity of quantum states is quite different from uncertainty or information contents, and involves the tradeoff between its classical and quantum features. In this work, we introduce a quantifier of complexity of continuous-variable states, e.g. quantum optical states, based on the Husimi quasiprobability distribution. This quantity is built upon two functions of the state: the Wehrl entropy, capturing the spread of the distribution, and the Fisher information with respect to location parameters, which captures the opposite behavior, i.e. localization in phase space. We analyze the basic properties of the quantifier and illustrate its features by evaluating complexity of Gaussian states and some relevant non-Gaussian states. We further generalize the quantifier in terms of s-ordered phase-space distributions and illustrate its implications.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"66 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145182764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Danial Motlagh, Robert A Lang, Paarth Jain, Jorge A Campos-Gonzalez-Angulo, William Maxwell, Tao Zeng, Alan Aspuru-Guzik and Juan Miguel Arrazola
{"title":"Quantum algorithm for vibronic dynamics: case study on singlet fission solar cell design","authors":"Danial Motlagh, Robert A Lang, Paarth Jain, Jorge A Campos-Gonzalez-Angulo, William Maxwell, Tao Zeng, Alan Aspuru-Guzik and Juan Miguel Arrazola","doi":"10.1088/2058-9565/ae0828","DOIUrl":"https://doi.org/10.1088/2058-9565/ae0828","url":null,"abstract":"Vibronic interactions between nuclear motion and electronic states are critical for the accurate modeling of photochemistry. However, accurate simulations of fully quantum non-adiabatic dynamics are often prohibitively expensive for classical methods beyond small systems. In this work, we present a quantum algorithm based on product formulas for simulating time evolution under a general vibronic Hamiltonian in real space, capable of handling an arbitrary number of electronic states and vibrational modes. We develop the first trotterization scheme for vibronic Hamiltonians beyond two electronic states and introduce an array of optimization techniques for the exponentiation of each fragment in the product formula, resulting in a remarkably low cost of implementation. To demonstrate practical relevance, we outline a proof-of-principle integration of our algorithm into a materials discovery pipeline for designing more efficient singlet fission-based organic solar cells. We estimate that 100 fs of propagation using a second-order Trotter product formula for a 6-state, 21-mode model of exciton transport at an anthracene dimer requires 154 qubits and 2.76 × 106 Toffoli gates. While a 4-state, 246-mode model describing charge transfer at an anthracene-fullerene interface requires 1053 qubits and 2.66 × 107 Toffoli gates.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"20 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145182799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Erin Sheridan, Michael Senatore, Samuel Schwab, Eric Aspling, Taylor Wagner, James Schneeloch, Stephen McCoy, Daniel Campbell, David Hucul, Zachary Smith and Matthew D LaHaye
{"title":"Noise-aware entanglement generation protocols for superconducting qubits with impedance-matched FBAR transducers","authors":"Erin Sheridan, Michael Senatore, Samuel Schwab, Eric Aspling, Taylor Wagner, James Schneeloch, Stephen McCoy, Daniel Campbell, David Hucul, Zachary Smith and Matthew D LaHaye","doi":"10.1088/2058-9565/ae08e0","DOIUrl":"https://doi.org/10.1088/2058-9565/ae08e0","url":null,"abstract":"Connecting superconducting quantum processors to telecommunications-wavelength quantum networks is critically necessary to enable distributed quantum computing, secure communications, and other applications. Optically-mediated entanglement heralding protocols offer a near-term solution that can succeed with imperfect components, including sub-unity efficiency microwave-optical quantum transducers. The viability and performance of these protocols relies heavily on the properties of the transducers used: the conversion efficiency, resonator lifetimes, and added noise in the transducer directly influence the achievable entanglement generation rate and fidelity of an entanglement generation protocol. Here, we use an extended Butterworth–van Dyke (BVD) model to optimize the conversion efficiency and added noise of a Thin film bulk acoustic resonator (FBAR) piezo-optomechanical transducer. We use the outputs from this model to calculate the fidelity of one-photon and two-photon entanglement heralding protocols in a variety of operating regimes. For transducers with matching circuits designed to either minimize the added noise or maximize conversion efficiency, we theoretically estimate that entanglement generation rates of greater than can be achieved at moderate pump powers with fidelities of . This is the first time a BVD equivalent circuit model is used to both optimize the performance of an FBAR transducer and to directly inform the design and implementation of an entanglement generation protocol. These results can be applied in the near term to realize quantum networks of superconducting qubits with realistic experimental parameters.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"106 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145182757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gisell Lorena Osorio, Milica Banić and Nicolás Quesada
{"title":"Strategies for generating separable photon triplets in waveguides and ring resonators","authors":"Gisell Lorena Osorio, Milica Banić and Nicolás Quesada","doi":"10.1088/2058-9565/ae0759","DOIUrl":"https://doi.org/10.1088/2058-9565/ae0759","url":null,"abstract":"Photon triplet sources exhibit non-Gaussian features, a key property for applications in quantum computing and quantum information. However, spectral correlations can limit the performance and detection efficiency of these systems. Motivated by this observation, we present a theoretical analysis of the spectral properties of photon triplets generated through spontaneous third-order parametric down-conversion in photonic devices, and discuss strategies to quantify and minimize such correlations. We propose two approaches: dispersion engineering in waveguides and pump engineering in resonators. We apply these strategies in two realistic source designs, namely a high-index-contrast optical fiber and a silicon nitride microring resonator. Finally, we discuss detection strategies for probing non-Gaussian features of the triplet state. We find that it is feasible to achieve few-mode generation of photon triplets using state-of-the-art experimental systems, a crucial step toward practical applications of photon triplet sources in quantum technologies.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"2 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pritam Chattopadhyay, Saikat Sur and Jonas F G Santos
{"title":"Generic two-mode Gaussian states as quantum sensors","authors":"Pritam Chattopadhyay, Saikat Sur and Jonas F G Santos","doi":"10.1088/2058-9565/ae03e8","DOIUrl":"https://doi.org/10.1088/2058-9565/ae03e8","url":null,"abstract":"Gaussian quantum channels constitute a cornerstone of continuous-variable quantum information science, underpinning a wide array of protocols in quantum optics and quantum metrology. While the action of such channels on arbitrary states is well-characterized under full channel knowledge, we address the inverse problem, namely, the precise estimation of fundamental channel parameters, including the beam splitter transmissivity and the two-mode squeezing amplitude. Employing the quantum Fisher information (QFI) as a benchmark for metrological sensitivity, we demonstrate that the symmetry inherent in mode mixing critically governs the amplification of QFI, thereby enabling high-precision parameter estimation. In addition, we investigate quantum thermometry by estimating the average photon number of thermal states, revealing that the transmissivity parameter significantly modulates estimation precision. Our results underscore the metrological utility of two-mode Gaussian states and establish a robust framework for parameter inference in noisy and dynamically evolving quantum systems.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"95 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145133769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bernd Bauerhenne, Lucas Tsunaki, Jan Thieme, Boris Naydenov and Kilian Singer
{"title":"Security analysis of ensemble-based quantum token protocol under advanced attacks","authors":"Bernd Bauerhenne, Lucas Tsunaki, Jan Thieme, Boris Naydenov and Kilian Singer","doi":"10.1088/2058-9565/ae03e7","DOIUrl":"https://doi.org/10.1088/2058-9565/ae03e7","url":null,"abstract":"We present and characterize advanced attacks on an ensemble-based quantum token protocol that allows for implementing non-clonable quantum coins. Multiple differently initialized tokens of identically prepared qubit ensembles are combined to a quantum coin that can be issued by a bank. A sophisticated attempt to copy tokens can assume that measurements on sub-ensembles can be carried through and that even individual qubits can be measured. Even though such an advanced attack might be perceived as technically unfeasible, we prove the security of the protocol under these conditions. We performed numerical simulations and verified our results by experiments on the IBM quantum platforms for different types of advanced attacks. Finally, we demonstrate that the security of the quantum coin can be made high by increasing the number of tokens. This paper in conjunction with provided numerical simulation tools verified against experimental data from the IBM quantum platforms allows for securely implementing our ensemble-based quantum token protocol with arbitrary quantum systems.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"86 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145127683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lucas Tsunaki, Bernd Bauerhenne, Malwin Xibraku, Martin E Garcia, Kilian Singer and Boris Naydenov
{"title":"Ensemble-based quantum token protocol benchmarked on IBM quantum processors","authors":"Lucas Tsunaki, Bernd Bauerhenne, Malwin Xibraku, Martin E Garcia, Kilian Singer and Boris Naydenov","doi":"10.1088/2058-9565/ae03e6","DOIUrl":"https://doi.org/10.1088/2058-9565/ae03e6","url":null,"abstract":"Quantum tokens envision to store unclonable quantum states in a physical device, with the goal of being used for personal authentication protocols, as required by banks. Still, the experimental realization of such devices faces many technical challenges, which can be partially mitigated using ensembles instead of single qubits. In this work, we thus propose an ensemble-based quantum token protocol, describing it through a simple yet general model based on a quantum mechanical observable. The protocol is benchmarked on five IBM quantum processors and a general hacker attack scenario is analyzed, in which the attacker attempts to read the bank token and forge a fake one, based on the information gained from this measurement. We experimentally demonstrate that the probability that the bank erroneously accepts a forged coin composed of multiple tokens can reach values below 10−22, while the probability that the bank accepts its own coin is above 0.999. The overall security of the protocol is therefore demonstrated within a hardware-agnostic framework, confirming the practical viability of the protocol in arbitrary quantum systems and thus paving the way for future applications with different ensembles of qubits, such as color center defects in solids.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"84 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145127578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dmitrii Dobrynin, Lorenzo Cardarelli, Markus Müller and Alejandro Bermudez
{"title":"Compressed-sensing Lindbladian quantum tomography with trapped ions","authors":"Dmitrii Dobrynin, Lorenzo Cardarelli, Markus Müller and Alejandro Bermudez","doi":"10.1088/2058-9565/ae0363","DOIUrl":"https://doi.org/10.1088/2058-9565/ae0363","url":null,"abstract":"Characterizing the dynamics of quantum systems is a central task for the development of quantum information processors (QIPs). It serves to benchmark different devices, learn about their specific noise, and plan the next hardware upgrades. However, this task is also very challenging, for it requires a large number of measurements and time-consuming classical processing. Moreover, when interested in the time dependence of the noise, there is an additional overhead since the characterization must be performed repeatedly within the time interval of interest. To overcome this limitation while, at the same time, ordering the learned sources of noise by their relevance, we focus on the inference of the dynamical generators of the noisy dynamics using Lindbladian quantum tomography (LQT). We propose two different improvements of LQT that alleviate previous shortcomings. In the weak-noise regime of current QIPs, we manage to linearize the maximum likelihood estimation of LQT, turning the constrained optimization into a convex problem to reduce the classical computation cost and to improve its robustness. Moreover, by introducing compressed sensing techniques, we reduce the number of required measurements without sacrificing accuracy. To illustrate these improvements, we apply our LQT tools to trapped-ion experiments of single- and two-qubit gates, advancing in this way the previous state of the art.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"28 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145116375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yi Hu, Congcong Zheng, Xiaojun Wang, Fanxu Meng, Xutao Yu and Zaichen Zhang
{"title":"Suppressing quantum errors by noise-aware circuit design","authors":"Yi Hu, Congcong Zheng, Xiaojun Wang, Fanxu Meng, Xutao Yu and Zaichen Zhang","doi":"10.1088/2058-9565/ae05c4","DOIUrl":"https://doi.org/10.1088/2058-9565/ae05c4","url":null,"abstract":"Suppressing errors is one of the central challenges in achieving reliable quantum computation on near-term hardware. While much attention has been paid to error correction and mitigation, we identify quantum circuit structure itself as a powerful lever for proactive error suppression. In this work, we present a unified and hardware-adaptive framework for noise-aware quantum circuit design, in which circuit topology and parameters are co-optimized from the ground up based on the noise profile of the target backend. Our framework supports a wide range of quantum tasks-including circuit compilation, quantum state preparation, and unitary approximation-under a consistent optimization paradigm. Extensive experiments on five IBM backends confirm the effectiveness of our method, showing significant fidelity gains across all tasks under realistic noise. These results demonstrate that noise suppression through structure-aware design offers a powerful and generalizable strategy for enhancing circuit performance on NISQ hardware. Our framework bridges low-level hardware constraints with high-level circuit synthesis, paving the way for more robust and efficient quantum programming in the presence of noise.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"22 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145103589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}