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Heuristic-free verification-inspired quantum benchmarking Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-04-02
Johannes Frank, Elham Kashefi, Dominik Leichtle and Michael de OliveiraIn this paper, we introduce a new approach to quantum benchmarking inspired by quantum verification, motivating new paradigms in quantum benchmarking. Our proposed benchmark not only serves as a robust indicator of computational capability but also offers scalability, customizability, and universality. By providing formal statements regarding the quality of quantum devices while assuming device consistency
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Continuous-variable multiplexed quantum repeater networks Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-04-02
Pei-Zhe Li, William J Munro, Kae Nemoto and Nicolò Lo PiparoContinuous-variable (CV) codes and their application in quantum communication have attracted increasing attention. In particular, one typical CV codes, cat-codes, has already been experimentally created using trapped atoms in cavities with relatively high fidelities. However, when these codes are used in a repeater protocol, the secret key rate (SKR) that can be extracted between two remote users is
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Ensuring superior learning outcomes and data security for authorized learner Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-04-02
Jeongho Bang, Wooyeong Song, Kyujin Shin and Yong-Su KimThe learner’s ability to generate a hypothesis that closely approximates the target function is crucial in machine learning. Achieving this requires sufficient data; however, unauthorized access by an eavesdropping learner can lead to security risks. Thus, it is important to ensure the performance of the ‘authorized’ learner by limiting the quality of the training data accessible to eavesdroppers.
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Weak value quantum metrology beyond weak interaction Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-04-01
Seung-Yeun Yoo, Yosep Kim, U-Shin Kim, Chung-Hyun Lee and Yoon-Ho KimWeak value amplification is crucial in quantum metrology because it enhances the detection of subtle interactions between quantum entities. However, current weak value quantum metrology techniques are only effective for extremely weak interactions, significantly narrowing its range of potential applications. In this work, we present the ‘metrological weak value (MWV)’, designed for use with quantum
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Collective preparation of large quantum registers with high fidelity Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-04-01
Lorenzo Buffoni and Michele CampisiWe report on the preparation of a large quantum register of 5612 qubits, with the unprecedented high global fidelity of . This was achieved by applying an improved cooperative quantum information erasure protocol (Buffoni and Campisi 2023 Quantum7 961) to a programmable network of superconducting qubits featuring a high connectivity. At variance with the standard method based on the individual reset
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Entangling cavity-magnon polaritons by interacting with phonons Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-04-01
Xuan Zuo, Zhi-Yuan Fan, Hang Qian, Rui-Chang Shen and Jie LiWe show how to entangle two cavity-magnon polaritons (CMPs) formed by two strongly coupled microwave cavity and magnon modes. This is realized by introducing vibration phonons, via magnetostriction, into the system that are dispersively coupled to the magnon mode. Stationary entanglement between two CMPs can be achieved when they are respectively resonant with the two sidebands of the drive field scattered
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The role of higher-order terms in trapped-ion quantum computing with magnetic gradient induced coupling Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-30
Sebastian Nagies, Kevin T Geier, Javed Akram, Junichi Okamoto, Dimitrios Bantounas, Christof Wunderlich, Michael Johanning and Philipp HaukeTrapped-ion hardware based on the magnetic gradient induced coupling (MAGIC) scheme is emerging as a promising platform for quantum computing. Nevertheless, in this—as in any other—quantum-computing platform, many technical questions still have to be resolved before large-scale and error-tolerant applications are possible. In this work, we present a thorough discussion of the structure and effects
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Quantum simulation of boson-related Hamiltonians: techniques, effective Hamiltonian construction, and error analysis Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-28
Bo Peng, Yuan Su, Daniel Claudino, Karol Kowalski, Guang Hao Low and Martin RoettelerElementary quantum mechanics proposes that a closed physical system consistently evolves in a reversible manner. However, control and readout necessitate the coupling of the quantum system to the external environment, subjecting it to relaxation and decoherence. Consequently, system-environment interactions are indispensable for simulating physically significant theories. A broad spectrum of physical
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Subspace preserving quantum convolutional neural network architectures Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-28
Léo Monbroussou, Jonas Landman, Letao Wang, Alex B Grilo and Elham KashefiSubspace preserving quantum circuits are a class of quantum algorithms that, relying on some symmetries in the computation, can offer theoretical guarantees for their training. Those algorithms have gained extensive interest as they can offer polynomial speed-up and can be used to mimic classical machine learning algorithms. In this work, we propose a novel convolutional neural network architecture
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A memristive neural decoder for cryogenic fault-tolerant quantum error correction Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-28
Victor Yon, Frédéric Marcotte, Pierre-Antoine Mouny, Gebremedhin A Dagnew, Bohdan Kulchytskyy, Sophie Rochette, Yann Beilliard, Dominique Drouin and Pooya RonaghNeural decoders for quantum error correction rely on neural networks to classify syndromes extracted from error correction codes and find appropriate recovery operators to protect logical information against errors. Its ability to adapt to hardware noise and long-term drifts make neural decoders promising candidates for inclusion in a fault-tolerant quantum architecture. However, given their limited
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Artificially intelligent Maxwell’s demon for optimal control of open quantum systems Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-27
Paolo A Erdman, Robert Czupryniak, Bibek Bhandari, Andrew N Jordan, Frank Noé, Jens Eisert and Giacomo GuarnieriFeedback control of open quantum systems is of fundamental importance for practical applications in various contexts, ranging from quantum computation to quantum error correction and quantum metrology. Its use in the context of thermodynamics further enables the study of the interplay between information and energy. However, deriving optimal feedback control strategies is highly challenging, as it
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Extractable energy from quantum superposition of current states Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-27
Francesco Perciavalle, Davide Rossini, Juan Polo and Luigi AmicoWe explore the energy content of superpositions of single-excitation current states. Specifically, we focus on the maximum energy that can be extracted from them through local unitary transformations. The figure of merit we employ is the local ergotropy. We consider an XY spin-chain model and perform a complete analysis in the whole range of the system parameters. This way, we prove that superpositions
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Trade-off between information gain and disturbance in local discrimination of entangled quantum states Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-27
Youngrong Lim, Minki Hhan and Hyukjoon KwonWe establish an information gain-disturbance trade-off relation in local state discrimination. Our result demonstrates a fundamental limitation of local strategy to discriminate entangled quantum states without disturbance, which becomes more difficult as the entanglement of the states to be discriminated increases. For a set of maximally entangled states (MESs), the capability of local strategy is
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Measurement of the work statistics of an open quantum system using a quantum computer Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-26
Lindsay Bassman Oftelie and Michele CampisiWe report on the experimental measurement of the work statistics of a genuinely open quantum system using a quantum computer. Such measurement has remained elusive thus far due to the inherent difficulty in measuring the total energy change of a system-bath compound (which is the work) in the open quantum system scenario. We overcome this difficulty by applying the interferometric scheme, originally
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Robust ultra-shallow shadows Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-25
Renato M S Farias, Raghavendra D Peddinti, Ingo Roth and Leandro AolitaWe present a robust shadow estimation protocol for wide classes of low-depth measurement circuits that mitigates noise as long as the effective measurement map including noise is locally unitarily invariant. This is in practice an excellent approximation, encompassing for instance the case of ideal single-qubit Clifford gates composing the first circuit layer of an otherwise arbitrary circuit architecture
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Lossy compression based on polar codes for high throughput information reconciliation in CV-QKD systems Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-20
Yameng Liu, Xue-Qin Jiang, Jisheng Dai, Han Hai and Peng HuangInformation reconciliation (IR) is a crucial component in the post-processing stage of continuous-variable quantum key distribution (CV-QKD) systems. However, the requirement to process a large amount of information in IR has become the bottleneck of realizing high-throughput CV-QKD systems, and the phenomenon of classical channel overloads appears. To solve these issues, we first propose a lossy compression
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Optimal control of spin qudits subject to decoherence using amplitude-and-frequency-constrained pulses Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-20
Alonso Hernández-Antón, Fernando Luis and Alberto CastroQuantum optimal control theory (QOCT) can be used to design the shape of electromagnetic pulses that implement operations on quantum devices. By using non-trivially shaped waveforms, gates can be made significantly faster than those built by concatenating monochromatic pulses. Recently, we applied this idea to the control of molecular spin qudits modeled with Schrödinger’s equation and showed it can
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Integrating quantum algorithms into classical frameworks: a predictor–corrector approach using HHL Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-18
Omer Rathore, Alastair Basden, Nicholas Chancellor and Halim KusumaatmajaThe application of quantum algorithms to classical problems is generally accompanied by significant bottlenecks when transferring data between quantum and classical states, often negating any intrinsic quantum advantage. Here we address this challenge for a well-known algorithm for linear systems of equations, originally proposed by Harrow, Hassidim and Lloyd (HHL), by adapting it into a predictor–corrector
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Two-photon interference at a telecom wavelength for quantum networking Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-18
Mathis Cohen, Laurent Labonté, Romain Dalidet, Sébastien Tanzilli and Anthony MartinThe interference between two independent photons stands as a crucial aspect of numerous quantum information protocols and technologies. In this work, we leverage fiber-coupled devices, which encompass fibered photon pair-sources and off-the-shelf optics, to demonstrate Hong-Ou-Mandel interference. We employ two distinct single photon sources, namely a heralded single-photon source and a weak coherent
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Scalable quantum eraser with superconducting integrated circuits Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-18
Ciro Micheletti Diniz, Celso J Villas-Boas and Alan C SantosA fast and scalable scheme for multi-qubit resetting in superconducting quantum processors is proposed by exploiting the feasibility of frequency-tunable transmon qubits and transmon-like couplers to engineer a full programmable superconducting erasing head. We demonstrate the emergence of collective effects that lead to a decoherence-free subspace during the erasing process. The presence of such a
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Transfer learning in predicting quantum many-body dynamics: from physical observables to entanglement entropy Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-17
Philipp Schmidt, Florian Marquardt, Naeimeh MohseniDeep neural networks have demonstrated remarkable efficacy in extracting meaningful representations from complex datasets. This has propelled representation learning as a compelling area of research across diverse fields. One interesting open question is how beneficial representation learning can be for quantum many-body physics, with its notoriously high-dimensional state space. In this work, we showcase
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Measurement schemes for quantum linear equation solvers Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-14
Andrew Patterson, Leigh LapworthSolving computational fluid dynamics (CFD) problems requires the inversion of a linear system of equations, which can be done using a quantum algorithm for matrix inversion (Gilyén et al 2019 Proc. 51st Annual ACM SIGACT Symp. on Theory of Computing 193–204). However, the number of shots required to measure the output of the system can be prohibitive and remove any advantage obtained by quantum computing
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Dynamical invariant based shortcut to equilibration in open quantum systems Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-13
Mohamed Boubakour, Shimpei Endo, Thomás Fogarty, Thomas BuschWe propose using the dynamical invariants, also known as the Lewis–Riesenfeld invariants, to speed-up the equilibration of a driven open quantum system. This allows us to reverse engineer the time-dependent master equation that describes the dynamics of the open quantum system and systematically derive a protocol that realizes a shortcut to equilibration. The method does not require additional constraints
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Photon-mediated dipole–dipole interactions as a resource for quantum science and technology in cold atoms Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-03-10
H H JenPhoton-mediated dipole–dipole interactions arise from atom-light interactions, which are universal and prevalent in a wide range of open quantum systems. This pairwise and long-range spin-exchange interaction results from multiple light scattering among the atoms. A recent surge of interests and progresses in both experiments and theories promises this core mechanism of collective interactions as a
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Effective field theories in broadband quantum optics: modeling phase modulation and two-photon loss from cascaded quadratic nonlinearities Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-28
Chris Gustin, Ryotatsu Yanagimoto, Edwin Ng, Tatsuhiro Onodera, Hideo MabuchiIn broadband quantum optical systems, nonlinear interactions among a large number of frequency components induce complex dynamics that may defy heuristic analysis. In this work we introduce a perturbative framework for factoring out reservoir degrees of freedom and establishing a concise effective model (effective field theory) for the remaining system. Our approach combines approximate diagonalization
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Quantum-centric computation of molecular excited states with extended sample-based quantum diagonalization Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-27
Stefano Barison, Javier Robledo Moreno, Mario MottaThe simulation of molecular electronic structure is an important application of quantum devices. Recently, it has been shown that quantum devices can be effectively combined with classical supercomputing centers in the context of the sample-based quantum diagonalization (SQD) algorithm. This allowed the largest electronic structure quantum simulation to date (77 qubits) and opened near-term devices
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A Gigahertz configurable silicon photonic integrated circuit nonlinear interferometer Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-21
Jonathan Frazer, Takafumi Ono, Jonathan C F MatthewsLow loss and high-speed processing of photons is important to photonic quantum information technologies. The speed with which quantum light generation can be modulated impacts the clock rate of photonic quantum computers, the data rate of quantum communication and applications of quantum enhanced radio-frequency sensors. Here we use lossy carrier depletion modulators in a silicon waveguide nonlinear
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High-rate continuous-variable measurement device-independent quantum key distribution with finite-size security Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-21
Adnan A E Hajomer, Ulrik L Andersen, Tobias GehringBuilding scalable and secure quantum networks requires advanced quantum key distribution (QKD) protocols that support multi-user connectivity. Continuous-variable (CV) measurement-device-independent (MDI) QKD, which eliminates all detector side-channel attacks, is a promising candidate for creating various quantum network topologies-such as quantum access networks and star-type topologies-using standard
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Non-iterative disentangled unitary coupled-cluster based on lie-algebraic structure Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-21
Mohammad Haidar, Olivier Adjoua, Siwar Badreddine, Alberto Peruzzo, Jean-Philip PiquemalDue to their non-iterative nature, fixed unitary coupled cluster (UCC) ansätze are attractive for performing quantum chemistry variational quantum eigensolver (VQE) computations as they avoid pre-circuit measurements on a quantum computer. However, achieving chemical accuracy for strongly correlated systems with UCC requires further inclusion of higher-order fermionic excitations beyond triples increasing
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Quantum coding with finite thermodynamic resources Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-19
Jake Xuereb, Tiago Debarba, Marcus Huber, Paul ErkerQuantum direct coding or Schumacher compression generalised the ideas of Shannon theory, gave an operational meaning to the von Neumann entropy and established the term qubit. But remembering that information processing is carried out by physical processes prompts one to wonder what thermodynamic resources are required to compress quantum information and how they constrain one’s ability to perform
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Simulating open quantum systems with giant atoms Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-18
Guangze Chen, Anton Frisk KockumOpen quantum many-body systems are of both fundamental and applicational interest. However, it remains an open challenge to simulate and solve such systems, both with state-of-the-art classical methods and with quantum-simulation protocols. To overcome this challenge, we introduce a simulator for open quantum many-body systems based on giant atoms, i.e. atoms (possibly artificial), that couple to a
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Finding quantum codes via Riemannian optimization Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-18
Miguel Casanova, Kentaro Ohki, Francesco TicozziWe propose a novel optimization scheme designed to find optimally correctable subspace codes for a known quantum noise channel. To each candidate subspace code we first associate a universal recovery map, as if the code was perfectly correctable, and aim to maximize a performance functional that combines a modified channel fidelity with a tuneable regularization term that promotes simpler codes. With
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Encoding proteins as quantum states with approximate quantum state preparation by iterated sparse state preparation Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-18
Rod Rofougaran, Ralph Wang, Akshay Ajagekar, Fengqi YouQuantum computing holds transformative potential for various domains including cheminformatics through advancements in quantum algorithms. The key to realizing improvements with quantum algorithms in cheminformatics is encoding chemical data like proteins as quantum states with quantum state preparation. In this work, we propose a computational framework to encode proteins as quantum states for efficient
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Quantum integration of decay rates at second order in perturbation theory Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-12
Jorge J Martínez de Lejarza, David F Rentería-Estrada, Michele Grossi, Germán RodrigoWe present the first quantum computation of a total decay rate in high-energy physics at second order in perturbative quantum field theory. This work underscores the confluence of two recent cutting-edge advances. On the one hand, the quantum integration algorithm quantum Fourier iterative amplitude estimation, which efficiently decomposes the target function into its Fourier series through a quantum
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Continuous-variable quantum key distribution with noisy squeezed states Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-11
Akash nag Oruganti, Ivan Derkach, Radim Filip, Vladyslav C UsenkoWe address the crucial role of noisy squeezing in security and performance of continuous-variable (CV) quantum key distribution (QKD) protocols. Squeezing has long been recognized for its numerous advantages in CV QKD, such as enhanced robustness against channel noise and loss, and improved secret key rates. However, the excess noise of the squeezed states, that unavoidably originates already from
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Comparing three generations of D-Wave quantum annealers for minor embedded combinatorial optimization problems Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-11
Elijah PelofskeQuantum annealing (QA) is a novel type of analog computation that aims to use quantum mechanical fluctuations to search for optimal solutions of Ising problems. QA in the transverse Ising model, implemented on D-Wave quantum processing units, are available as cloud computing resources. In this study we report concise benchmarks across three generations of D-Wave quantum annealers, consisting of four
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Self-guided tomography of time-frequency qudits Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-11
Laura Serino, Markus Rambach, Benjamin Brecht, Jacquiline Romero, Christine SilberhornHigh-dimensional time-frequency encodings have the potential to significantly advance quantum information science; however, practical applications require precise knowledge of the encoded quantum states, which becomes increasingly challenging for larger Hilbert spaces. Self-guided tomography (SGT) has emerged as a practical and scalable technique for this purpose in the spatial domain. Here, we apply
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Quantum-enhanced clock synchronization using prior statistical information Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-10
Ronakraj K Gosalia, Robert MalaneyOptical frequency combs (OFCs) are paving the way for an unprecedented level of precision in synchronizing optical clocks over free-space. However, the conventional intensity-based strategy for estimating the timing offset between two OFCs is sub-optimal, whereas a strategy based on temporal modes can achieve the optimal precision bound under ideal conditions. In practice, the performance of both strategies
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Proof-of-work consensus by quantum sampling Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-07
Deepesh Singh, Gopikrishnan Muraleedharan, Boxiang Fu, Chen-Mou Cheng, Nicolas Roussy Newton, Peter P Rohde, Gavin K BrennenSince its advent in 2011, boson sampling has been a preferred candidate for demonstrating quantum advantage because of its simplicity and near-term requirements compared to other quantum algorithms. We propose to use a variant, called coarse-grained boson-sampling (CGBS), as a quantum proof-of-work (PoW) scheme for blockchain consensus. The miners perform boson sampling using input states that depend
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Adaptive circuit learning of born machine: towards realization of amplitude embedding and quantum data loading Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-07
Chun-Tse Li, Hao-Chung ChengQuantum data loading plays a central role in quantum algorithms and quantum information processing. Many quantum algorithms hinge on the ability to prepare arbitrary superposition states as a subroutine, with claims of exponential speedups often predicated on access to an efficient data-loading oracle. In practice, constructing a circuit to prepare a generic n-qubit quantum state typically demands
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Quantum thermal machine as a rectifier Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-07
M Santiago-García, O Pusuluk, Ö E Müstecaplıoğlu, B Çakmak, R Román-AncheytaWe study a chain of interacting individual quantum systems connected to heat baths at different temperatures on both ends. Starting with the two-system case, we thoroughly investigate the conditions for heat rectification (asymmetric heat transport), compute thermal conductance, and generalize the results to longer chains. We find that heat rectification in the weak coupling regime can be independent
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Accelerating multipartite entanglement generation in non-Hermitian superconducting qubits Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-07
Chimdessa Gashu Feyisa, J-S You, Huan-Yu Ku, H H JenOpen quantum systems are susceptible to losses in information, energy, and particles due to their surrounding environment. One novel strategy to mitigate these losses is to transform them into advantages for quantum technologies through tailored non-Hermitian quantum systems. In this work, we theoretically propose a fast generation of multipartite entanglement in non-Hermitian qubits. Our findings
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Experimental simulation of daemonic work extraction in open quantum batteries on a digital quantum computer Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-06
Seyed Navid Elyasi, Matteo A C Rossi, Marco G GenoniThe possibility of extracting more work from a physical system thanks to the information obtained from measurements has been a topic of fundamental interest in the context of thermodynamics since the formulation of the Maxwell’s demon thought experiment. We here consider this problem from the perspective of an open quantum battery interacting with an environment that can be continuously measured. By
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Quadrature-PT symmetry: classical-to-quantum transition in noise fluctuations Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-06
Wencong Wang, Yanhua Zhai, Dongmei Liu, Xiaoshun Jiang, Saeid Vashahri Ghamsari, Jianming WenWhile gain-loss-coupled photonic platforms have achieved significant success in studying classical parity-time (PT) symmetry, they encounter challenges in demonstrating pure quantum effects due to incompatible operator transformations and Langevin noise. Here, we present compelling evidence that a non-Hermitian (NH) twin-beam system, undergoing phase-sensitive amplification and balanced loss, not only
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Asymmetric secure multi-party quantum computation with weak clients against dishonest majority Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-06
Theodoros Kapourniotis, Elham Kashefi, Dominik Leichtle, Luka Music, Harold OllivierSecure multi-party computation (SMPC) protocols allow several parties distrusting each other to collectively compute a function on their inputs, without revealing the input values. In this paper, we introduce a protocol that lifts SMPC to its quantum counterpart—secure multi-party quantum computation (SMPQC) for classical inputs and outputs—in a composable and statistically secure way, even for a single
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Characterization and thermometry of dissipatively stabilized steady states Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-04
G S Grattan, A M Liguori-Schremp, D Rodriguez Perez, E Kapit, W Jones, P GrafIn this work we study the properties of dissipatively stabilized steady states of noisy quantum algorithms, exploring the extent to which they can be well approximated as thermal distributions, and proposing methods to extract the effective temperature T. We study an algorithm called the relaxational quantum eigensolver (RQE), which is one of a family of algorithms that attempt to find ground states
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Heat transport in the quantum Rabi model: universality and ultrastrong coupling effects Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-04
L Magazzù, E Paladino, M GrifoniHeat transport in a qubit–oscillator junction described by the quantum Rabi model is investigated. Upon variation of temperature, bias on the qubit and the qubit–oscillator coupling strength, a rich variety of effects is identified. For weak coupling to bosonic heat baths, transport is essentially controlled by the qubit–oscillator coupling g which defines a Kondo-like temperature TK(g). At temperatures
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Security of hybrid BB84 with heterodyne detection Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-03
Jasminder S Sidhu, Rocco Maggi, Saverio Pascazio, Cosmo LupoQuantum key distribution (QKD) promises everlasting security based on the laws of physics. Most common protocols are grouped into two distinct categories based on the degrees of freedom used to carry information, which can be either discrete or continuous, each presenting unique advantages in either performance, feasibility for near-term implementation, and compatibility with existing telecommunications
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Robustness of diabatic enhancement in quantum annealing Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-03
Natasha Feinstein, Ivan Shalashilin, Sougato Bose, P A WarburtonIn adiabatic quantum annealing, the speed with which an anneal can be run, while still achieving a high final ground state (GS) fidelity, is dictated by the size of the minimum gap that appears between the ground and first excited state in the annealing spectrum. To avoid the exponential slowdown associated with exponentially closing gaps, diabatic transitions to higher energy levels may be exploited
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Scalable high-dimensional multipartite entanglement with trapped ions Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-31
Harsh Vardhan Upadhyay, Sanket Tripathy, Ting Rei Tan, Baladitya Suri, Athreya ShankarWe propose a protocol for the preparation of generalized Greenberger–Horne–Zeilinger (GHZ) states of N atoms each with d = 3 or 4 internal levels. We generalize the celebrated one-axis twisting (OAT) Hamiltonian for N qubits to qudits by including OAT interactions of equal strengths between every pair of qudit levels, a protocol we call as balanced OAT (BOAT). Analogous to OAT for qubits, we find that
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Towards enhanced precision in thermometry with nonlinear qubits Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-29
Sebastian DeffnerQuantum thermometry refers to the study of measuring ultra-low temperatures in quantum systems. The precision of such a quantum thermometer is limited by the degree to which temperature can be estimated by quantum measurements. More precisely, the maximal precision is given by the inverse of the quantum Fisher information. In the present analysis, we show that quantum thermometers that are described
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Quantum algorithm for polaritonic chemistry based on an exact ansatz Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-28
Samuel Warren, Yuchen Wang, Carlos L Benavides-Riveros, David A MazziottiCavity-modified chemistry uses strong light-matter interactions to modify the electronic properties of molecules in order to enable new physical phenomena such as novel reaction pathways. As cavity chemistry often involves critical regions where configurations become nearly degenerate, the ability to treat multireference problems is crucial to understanding polaritonic systems. In this Letter, we show
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Quantum data encoding as a distinct abstraction layer in the design of quantum circuits Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-28
Gabriele Agliardi, Enrico PratiComplex quantum circuits are constituted by combinations of quantum subroutines. The computation is possible as long as the quantum data encoding is consistent throughout the circuit. Despite its fundamental importance, the formalization of quantum data encoding has never been addressed systematically so far. We formalize the concept of quantum data encoding, namely the format providing a representation
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Distributing quantum correlations through local operations and classical resources Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-27
Adam G Hawkins, Hannah McAleese, Mauro PaternostroDistributing quantum correlations to each node of a network is a key aspect of quantum networking. Here, we present a robust, physically motivated protocol by which global quantum correlations, as characterized by the discord, can be distributed to quantum memories using a mixed state of information carriers which possesses only classical correlations. In addition, such distribution is done using only
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Atom interferometer as a freely falling clock for time-dilation measurements Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-22
Albert RouraLight-pulse atom interferometers based on single-photon transitions are a promising tool for gravitational-wave detection in the mid-frequency band and the search for ultralight dark-matter fields. Here we present a novel measurement scheme that enables their use as freely falling clocks directly measuring relativistic time-dilation effects. The proposal is particularly timely because it can be implemented
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Learning to classify quantum phases of matter with a few measurements Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-20
Mehran Khosrojerdi, Jason L Pereira, Alessandro Cuccoli, Leonardo BanchiWe study the identification of quantum phases of matter, at zero temperature, when only part of the phase diagram is known in advance. Following a supervised learning approach, we show how to use our previous knowledge to construct an observable capable of classifying the phase even in the unknown region. By using a combination of classical and quantum techniques, such as tensor networks, kernel methods
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Conditions for a quadratic quantum speedup in nonlinear transforms with applications to energy contract pricing Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-16
Gabriele Agliardi, Corey O’Meara, Kavitha Yogaraj, Kumar Ghosh, Piergiacomo Sabino, Marina Fernández-Campoamor, Giorgio Cortiana, Juan Bernabé-Moreno, Francesco Tacchino, Antonio Mezzacapo, Omar ShehabComputing nonlinear functions over multilinear forms is a general problem with applications in risk analysis. For instance in the domain of energy economics, accurate and timely risk management demands for efficient simulation of millions of scenarios, largely benefiting from computational speedups. We develop a novel hybrid quantum–classical algorithm based on polynomial approximation of nonlinear
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Automated quantum system modeling with machine learning Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-16
K Mukherjee, J Schachenmayer, S Whitlock, S WüsterDespite the complexity of quantum systems in the real world, models with just a few effective many-body states often suffice to describe their quantum dynamics, provided decoherence is accounted for. We show that a machine learning algorithm is able to construct such models, given a straightforward set of quantum dynamics measurements. The effective Hilbert space can be a black box, with variations
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Challenging excited states from adaptive quantum eigensolvers: subspace expansions vs. state-averaged strategies Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-10
Harper R Grimsley, Francesco A EvangelistaThe prediction of electronic structure for strongly correlated molecules represents a promising application for near-term quantum computers. Significant attention has been paid to ground state wavefunctions, but excited states of molecules are relatively unexplored. In this work, we consider the adaptive, problem-tailored (ADAPT)-variational quantum eigensolver (VQE) algorithm, a single-reference approach
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Fast, low-loss, all-optical phase modulation in warm rubidium vapour Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-09
William O C Davis, Paul Burdekin, Tabijah Wasawo, Sarah E Thomas, Peter J Mosley, Joshua Nunn, Cameron McGarryLow-loss high-speed switches are an integral component of future photonic quantum technologies, with applications in state generation, multiplexing, and the implementation of quantum gates. Phase modulation is one method of achieving this switching; however, existing optical phase modulators offer either high bandwidth or low loss—not both. We demonstrate fast (100 MHz bandwidth), low-loss ( 83(2)%