Peer Revenue Equity in science

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics Quantum Physics

quant-ph Watch Quantum Physics

Saturday 17 January

Quantum Physics

Physical probability in the Everett interpretation and Bell inequalities

Simon Saunders

I define a notion of locality LOC, closely modelled on Bell's principle of local causality, construed as the condition that single-case probabilities cannot be modified by actions at spacelike separation. The new principle, like Bell's, forces Bell inequalities, but with two loopholes: one is violation of measurement independence, known to Bell, but the other is non-uniqueness of remote outcomes, a loophole only for LOC, not for Bell's principle. I also set out a theory of physical probability, applicable to the Everett interpretation, in which the Born rule is derived, and which therefore violates Bell inequalities. I show it is consistent with LOC. Surprisingly, both loopholes are exploited. I conclude not only that physical probability in the Everett interpretation involves no action at a distance, in the sense of LOC, but that the observed violation of Bell inequalities is powerful evidence for many worlds.
Read the full abstract

2601.12159 · 17 Jan · To appear in Local Quantum Mechanics: Everett, many worlds, and reality, A. Ney (ed.), Oxford University Press. This is a revised version of arXiv: 2601.12159, the latter a revision of arXiv:2512.00575. It is identical to the published version

Abstract PDF

Quantum Physics

Quantum interference between spectral bandwidth mismatched photons

Jan Krzyżanowski, Jerzy Szuniewicz, Sanjay Kapoor et al. (+2 more)

Two-photon interference is a cornerstone of photonic quantum technologies. However, its practical use in hybrid architectures is constrained by the need for photon indistinguishability, particularly in linewidth and the associated time scale. While narrowband filtering can improve interference visibility, it introduces significant photon loss - a critical limitation for applications. Here, we experimentally demonstrate an efficient approach to enable non-classical two-photon interference between spectral-bandwidth mismatched photons using an electro-optic time lens. We increase the visibility of Hong-Ou-Mandel (HOM) interference between spectral bandwidth mismatched photons from $(31.0\pm1.7)\%$, to $(91.7\pm2.6)\%$, with correction for accidental coincidences, achieving highly non-classical two-photon interference visibility without spectral filtering. Moreover, we demonstrate a simultaneous correction of the central wavelength mismatch of $\pm1.1$ nm, while maintaining the non-classical interference visibility. This result opens the possibility to efficiently integrate quantum systems operating at different time scales for hybrid quantum communication, teleportation, entanglement swapping, distributed sensing, and hybrid quantum computing.
Read the full abstract

All authors Jan Krzyżanowski, Jerzy Szuniewicz, Sanjay Kapoor, Filip Sośnicki, Michał Karpiński

Quantum Physics · Cross-listed from cond-mat.stat-mech

Measurement-induced crossover in quantum first-detection times

Giovanni Di Fresco, Aldo Coraggio, Alessandro Silva et al. (+1 more)

The quantum first-detection problem concerns the statistics of the time at which a system, subject to repeated measurements, is observed in a prescribed target state for the first time. Unlike its classical counterpart, the measurement back action intrinsic to quantum mechanics may profoundly alter the system dynamics. Here we show that it induces a distinct change in the statistics of the first-detection time. For a quantum particle in one spatial dimension subject to stroboscopic measurements, we observe an algebraic decay of the probability of the first-detection time if the particle is free, an exponential decay in the presence of a confining potential, and a time-dependent crossover between these behaviors if the particle is partially confined. This crossover reflects the purely quantum nature of the detection process, which fundamentally distinguishes it from the first-passage problem in classical systems.
Read the full abstract

All authors Giovanni Di Fresco, Aldo Coraggio, Alessandro Silva, Andrea Gambassi

Quantum Physics

Probing multiparameter quantum estimation in the process $e^+e^-\to J/\psi \to \text{B}\bar{\text{B}}$ at BESIII

Elhabib Jaloum and Mohamed Amazioug

The quantum Fisher information matrix (QFIM) is the cornerstone of multiparameter quantum metrology. In this work, we investigate multiparameter quantum estimation in baryon-antibaryon (B bar-B) pairs produced via the e+ e- -> J/psi -> B bar-B process at the BESIII experiment, utilizing the symmetric logarithmic derivative (SLD) formalism. Moreover, the QFIM defines the quantum Cramer-Rao bound and dictates the choice of optimal probe states. We compare individual and simultaneous estimation strategies for two key physical parameters: the scattering angle phi and the decay parameter alpha_psi. The estimation variances are found to depend strongly on the explored region of the (phi, alpha_psi) parameter space and to display markedly different temporal dynamics. In general, higher true values of a parameter increase the system's sensitivity, thereby significantly reducing the associated variance. While both variances increase with evolution time, they do so at distinct rates, revealing parameter-dependent information loss driven by environmental decoherence. These findings demonstrate the utility of the QFIM framework for multiparameter quantum estimation in realistic open systems and provide new insights into the ultimate precision limits achievable for hyperon decay parameters.
Read the full abstract

Quantum Physics

An unexpected theoretical structure that could explain quantum-mechanics postulates like the Born rule and the wave-function reduction

Léon Brenig and Marc Vincke

A unique postulate is shown to underly the whole quantum mechanics theory: the invariance of the Heisenberg uncertainty inequality under a group of special nonlinear gauge transformations (NLGT). With this postulate, the quantum mechanics of a free particle is derived from classical mechanics, including the statements of the postulates of quantum mechanics, except for the wave-function-collapse postulate. An explanatory mechanism for the latter postulate is derived by performing an analytical continuation of the NLGTs. This extension results in a Schrödinger-bridge process, intertwined under the NLGT with the standard unitary quantum evolution, and revealing non-quantum (or beyond-quantum) phenomena. Mechanisms of that latter kind, like the ones associated to the quantum measurement process, occur in a new space-like dimension and hence are non causal in nature, in opposition to a time evolution. The present exercice focusses on the free particle in order to highlight the features of the performed derivation in the simplest possible way. Work is in progress to extend the performed derivation beyond that simple case.
Read the full abstract

Quantum Physics

Peres-type Criterion of Einstein-Podolsky-Rosen Steering for Two Qubits

Yu-Xuan Zhang and Jing-Ling Chen

Quantum nonlocality manifests in multipartite systems through entanglement, Bell's nonlocality, and Einstein-Podolsky-Rosen (EPR) steering. While Peres's positive-partial-transpose criterion provides a simple and powerful test for entanglement, a comparably elegant spectral criterion for detecting EPR steering remains an open challenge. In this work, we systematically explore whether a Peres-type criterion can be established for EPR steering in the two-qubit system. Focusing on rank-2 (including rank-1) states and the two-qubit Werner state, we analyze the eigenvalues of their partially transposed density matrices and construct a significant steering criterion based on symmetric combinations of these eigenvalues. We prove that this criterion serves as a necessary and sufficient condition for steerability for the Werner state, all two-qubit pure states, all two-qubit rank-2 states. Furthermore, we validate the criterion for higher-rank states (rank-3 and rank-4) and show that the results align with known steering inequalities. Our findings suggest a more unified framework for detecting quantum nonlocality via partial transposition and open avenues for further theoretical and numerical investigations into steering detection.
Read the full abstract

Quantum Physics

Temperature effect on a kicked Tonks-Girardeau gas

Ang Yang, Yue Chen and Lei Ying

It is widely recognized that finite temperatures degrade quantum coherence and can induce thermalization. Here, we study the effect of finite temperature on a kicked Tonks–Girardeau gas, which is known to exhibit many–body dynamical localization and delocalization under periodic and quasiperiodic kicks, respectively. We find that many–body dynamical localization persists at finite–and even high–temperatures, although the coherence of the localized state is further degraded. In particular, we demonstrate a modified effective thermalization of the localized state by considering the initial temperature. Moreover, we show many–body dynamical localization transition at intermediate temperature. Our work extends the study of many–body dynamical localization and delocalization to the finite–temperature regime, providing guidance for cold-atom experiments, particularly in the strongly-interacting regime.
Read the full abstract

Quantum Physics

Contour-integral based quantum eigenvalue transformation: analysis and applications

Shan Jiang and Dong An

Eigenvalue transformations appear ubiquitously in scientific computation, ranging from matrix polynomials to differential equations, and are beyond the reach of the quantum singular value transformation framework. In this work, we study the efficiency of quantum algorithms based on contour integral representation for eigenvalue transformations from both theoretical and practical aspects. Theoretically, we establish a complete complexity analysis of the contour integral approach proposed in [Takahira, Ohashi, Sogabe, and Usuda. Quant. Inf. Comput., 22, 11&12, 965–979 (2021)]. Moreover, we combine the contour integral approach and the sampling-based linear combination of unitaries to propose a quantum algorithm for estimating observables of eigenvalue transformations using only $3$ additional qubits. Practically, we design contour integral based quantum algorithms for linear ordinary differential equations, $\varphi$-functions, Fréchet derivatives of matrix functions, and matrix functions. In particular, we show that the contour integral algorithm can outperform all the existing quantum algorithms in the case of solving asymptotically stable differential equations.
Read the full abstract

Quantum Physics · Cross-listed from cs.LG

Trainability-Oriented Hybrid Quantum Regression via Geometric Preconditioning and Curriculum Optimization

Qingyu Meng and Yangshuai Wang

Quantum neural networks (QNNs) have attracted growing interest for scientific machine learning, yet in regression settings they often suffer from limited trainability under noisy gradients and ill-conditioned optimization. We propose a hybrid quantum–classical regression framework designed to mitigate these bottlenecks. Our model prepends a lightweight classical embedding that acts as a learnable geometric preconditioner, reshaping the input representation to better condition a downstream variational quantum circuit. Building on this architecture, we introduce a curriculum optimization protocol that progressively increases circuit depth and transitions from SPSA-based stochastic exploration to Adam-based gradient fine-tuning. We evaluate the approach on PDE-informed regression benchmarks and standard regression datasets under a fixed training budget in a simulator setting. Empirically, the proposed framework consistently improves over pure QNN baselines and yields more stable convergence in data-limited regimes. We further observe reduced structured errors that are visually correlated with oscillatory components on several scientific benchmarks, suggesting that geometric preconditioning combined with curriculum training is a practical approach for stabilizing quantum regression.
Read the full abstract

Quantum Physics

Impact of Circuit Depth versus Qubit Count on Variational Quantum Classifiers for Higgs Boson Signal Detection

Fatih Maulana

High-Energy Physics (HEP) experiments, such as those at the Large Hadron Collider (LHC), generate massive datasets that challenge classical computational limits. Quantum Machine Learning (QML) offers a potential advantage in processing high-dimensional data; however, finding the optimal architecture for current Noisy Intermediate-Scale Quantum (NISQ) devices remains an open challenge. This study investigates the performance of Variational Quantum Classifiers (VQC) in detecting Higgs Boson signals using the ATLAS Higgs Boson Machine Learning Challenge 2014 experiment dataset. We implemented a dimensionality reduction pipeline using Principal Component Analysis (PCA) to map 30 physical features into 4-qubit and 8-qubit latent spaces. We benchmarked three configurations: (A) a shallow 4-qubit circuit, (B) a deep 4-qubit circuit with increased entanglement layers, and (C) an expanded 8-qubit circuit. Experimental results demonstrate that increasing circuit depth significantly improves performance, yielding the highest accuracy of 56.2% (Configuration B), compared to a baseline of 51.9%. Conversely, simply scaling to 8 qubits resulted in a performance degradation to 50.6% due to optimization challenges associated with Barren Plateaus in the larger Hilbert space. These findings suggest that for near-term quantum hardware, prioritizing circuit depth and entanglement capability is more critical than increasing qubit count for effective anomaly detection in HEP data.
Read the full abstract

Quantum Physics

Indoor Occupancy Classification using a Compact Hybrid Quantum-Classical Model Enabled by a Physics-Informed Radar Digital Twin

Sebastian Ratto, Ahmed N. Sayed, Neda Rojhani et al. (+6 more)

Indoor occupancy classification enables privacy-preserving monitoring in settings such as remote elder care, where presence information helps triage alarms without cameras or wearables. Radar suits this role by sensing motion through occlusions and in darkness. Modern deep-learning pipelines are the standard for interpreting radar returns effectively; however, they are often parameter-heavy and sensitive at low signal-to-noise ratios (SNR), motivating compact alternatives like Hybrid Quantum Neural Networks (HQNNs). A two-qubit HQNN is benchmarked against convolutional neural networks (CNNs) using a physics-informed 60GHz digital twin and real radar measurements under matched training protocols. In clean conditions, the HQNN achieves high accuracy (99.7% synthetic; 97.0% real) with up to 170x fewer parameters (0.066M). Its parameter efficiency is shown to be structural, as an ablation of the parameterized quantum circuit (PQC) causes sharp performance drops on real data (to 68.5% and 31.5% for the control heads). A domain-dependent sensitivity emerges under additive-noise evaluation, where the HQNN begins recovery earlier in synthetic data while CNNs recover more steeply and peak higher on real measurements. In label-fraction ablations, CNNs prove more sample-efficient on real Range-Doppler Maps (RDMs), with the performance gap being most pronounced (at 50% labels, BA 0.89-0.99 vs. HQNN 0.75). On synthetic data, this gap narrows significantly, largely vanishing by the 50% label mark. Overall, the HQNN's value lies in parameter efficiency and a compact inductive bias that shapes its distinct sensitivity profile; this work establishes a rigorous baseline for hybrid quantum models in privacy-preserving radar occupancy sensing.
Read the full abstract

All authors Sebastian Ratto, Ahmed N. Sayed, Neda Rojhani, Arien P. Sligar, Jose R. Rosas-Bustos, Saasha Joshi, Luke C. G. Govia, Omar M. Ramahi, George Shaker

Quantum Physics

Scalable and telecom single-erbium system with record-long room-temperature quantum coherence

Alex Kaloyeros, Natasha Tabassum and Spyros Gallis

Achieving long lived ({\mu}s-scale) quantum coherence at room temperature in the telecom C band remains a central unsolved challenge for solid state quantum platforms, with coherence at this timescale previously demonstrated only under vacuum cryogenic conditions at temperatures over 600 times lower. To this end, we introduce a CMOS-compatible nanoengineering approach that deterministically controls the number of Er ions within a nanoscale volume and their electromagnetic environment using sub 5 nm silicon based hollow nanopillars, which achieves the first deterministic spatial isolation of single erbium ions. This nanostructure-enabled isolation suppresses ion-ion interactions and local electromagnetic field noise, enabling single-erbium-ion operation under ambient conditions. The resulting individually addressable single-ion devices exhibit record room temperature optical coherence times of T2* = ~32 {\mu}s in the telecom C-band (limited by the coherence of the laser) and extending to > 100 {\mu}s based on photon echo measurements. We further present the first demonstration of background free, upconversion enabled single photon emission from multilevel erbium qudits, providing high contrast coherent optical readout. Beyond these performance gains, our work, through sub-5-nm nanoscale engineering, establishes isolated single-ion environments as a viable route to room-temperature operation for solid-state quantum systems. This approach has the potential to address the long-standing barrier of room-temperature decoherence and open a manufacturable, telecom-compatible pathway toward scalable quantum networks, distributed sensing, and cryogenic-free quantum photonic integrated circuits.
Read the full abstract

Friday 16 January

Quantum Physics · Cross-listed from physics.soc-ph

Meeting the Needs of the Global Quantum Science Community: A Call to Action

Tzula B. Propp, Brandy Todd, Sara A. Metwalli et al. (+8 more)

2025 marks one hundred years since the discovery of quantum mechanics. In the century since then, quantum science has blossomed into a global community composed of academics, engineers, developers, and entrepreneurs. The world is currently in the middle of the so-called second quantum revolution, with increased public awareness of quantum science and technology, and growing investment in both quantum hardware and software applications. However, representation remains low among historically marginalized groups: women, LGBTQ+, BIPOC, and people from the global south make up disproportionately few physicists. There are numerous efforts to improve diversity within quantum science, including through workforce development. But many of the changes enacted at the highest levels have failed to result in real change, as highlighted and discussed in the recent Women For Quantum Manifesto of Values. Here, we seek to echo and amplify the need for real change in the quantum ecosystem, emphasizing intersectionality and a feminist approach that centers the most vulnerable members of the quantum community: young students and researchers, especially those communities historically marginalized from quantum science. This report is our attempt to help quantum communities meet this need; we have conducted a survey of quantum scientists all over the world, and here we include both a preliminary report of our findings and policy suggestions we have built to address them. The primary results of our survey are that, 1) marginalized quantum scientists are experiencing hardships and challenges more than their more privileged peers across all metrics, 2) that this fact is hurting retention of diverse, talented quantum scientists in our field, and 3) quantum EDI is an investment in talent retention and resilience building, which are essential for a thriving, globally competitive quantum ecosystem.
Read the full abstract

All authors Tzula B. Propp, Brandy Todd, Sara A. Metwalli, Alina Helena S. Gallardo, Michael Dascal, Denise Ruffner, Klaus D. Jöns, Shaeema Zaman, Judith Kreukels, Marilù Chiofalo, Lydia Sanmartí-Vila

Quantum Physics

Any local Hamiltonian with ferromagnetic quantum many-body scars has a generalized Shiraishi-Mori form

Keita Omiya

Quantum many-body scars (QMBS) are nonthermal eigenstates embedded in otherwise thermal spectra. A broad class of exact QMBS is realized as fixed-momentum magnon states above a ferromagnetic reference state. Here we prove a structural theorem for this class. Specifically, we show that any local Hamiltonian hosting such “ferromagnetic scar states” necessarily admits a decomposition into a Zeeman term and terms containing local projectors that annihilate the scar states locally. This result establishes that an appropriate generalization of the Shiraishi–Mori construction is essentially exhaustive for ferromagnetic QMBS and provides a unified structural explanation for the recurrent appearance of projector-based interactions and equally spaced scar towers across a broad family of exact scar Hamiltonians.
Read the full abstract

Quantum Physics · Cross-listed from cond-mat.mtrl-sci

Quantum Kernel Machine Learning for Autonomous Materials Science

Felix Adams, Daiwei Zhu, David W. Steuerman et al. (+2 more)

Autonomous materials science, where active learning is used to navigate large compositional phase space, has emerged as a powerful vehicle to rapidly explore new materials. A crucial aspect of autonomous materials science is exploring new materials using as little data as possible. Gaussian process-based active learning allows effective charting of multi-dimensional parameter space with a limited number of training data, and thus is a common algorithmic choice for autonomous materials science. An integral part of the autonomous workflow is the application of kernel functions for quantifying similarities among measured data points. A recent theoretical breakthrough has shown that quantum kernel models can achieve similar performance with less training data than classical models. This signals the possible advantage of applying quantum kernel machine learning to autonomous materials discovery. In this work, we compare quantum and classical kernels for their utility in sequential phase space navigation for autonomous materials science. Specifically, we compute a quantum kernel and several classical kernels for x-ray diffraction patterns taken from an Fe-Ga-Pd ternary composition spread library. We conduct our study on both IonQ's Aria trapped ion quantum computer hardware and the corresponding classical noisy simulator. We experimentally verify that a quantum kernel model can outperform some classical kernel models. The results highlight the potential of quantum kernel machine learning methods for accelerating materials discovery and suggest complex x-ray diffraction data is a candidate for robust quantum kernel model advantage.
Read the full abstract

All authors Felix Adams, Daiwei Zhu, David W. Steuerman, A. Gilad Kusne, Ichiro Takeuchi

Quantum Physics

Entanglement Distribution over a Polarization-Stabilized Aerial Fiber

Yicheng Shi, Jing Su, Anouar Rahmouni et al. (+9 more)

We experimentally demonstrate the distribution of polarization-entangled photons across a 62-km, partially-aerial fiber. With polarization stabilization applied to the fiber link, we achieve a photon pair rate of approximately 1500 per second and observe a CHSH inequality violation with S=2.34.
Read the full abstract

All authors Yicheng Shi, Jing Su, Anouar Rahmouni, Pranish Shrestha, Mheni Merzouki, Gabriel Bello Portmann, Anne Lazenby, Mael Flament, Mehdi Namazi, Abdella Battou, Oliver Slattery, Thomas Gerrits

Quantum Physics · Cross-listed from math.RA

Multiary gradings

Steven Duplij

This article develops a comprehensive theory of multiary graded polyadic algebras, extending the classical concept of group-graded algebras to higher-arity structures. We introduce the notion of grading by multiary groups and investigate various compatibility conditions between the arity of algebra operations and grading group operations. Key results include quantization rules connecting arities, classification of graded homomorphisms, the First Isomorphism Theorem for graded polyadic algebras and concrete examples including ternary superalgebras and polynomial algebras over $n$-ary matrices. The theory reveals fundamentally new phenomena not present in the binary case, such as the existence of higher power gradings and nontrivial constraints on arity compatibility.
Read the full abstract

Quantum Physics · Cross-listed from cond-mat.mtrl-sci

Homogeneous Microwave Delivery for Quantum Sensing with Nitrogen-Vacancy Centers at High Pressures

Timothy A. Elmslie, Luca Basso, Adam Dodson et al. (+2 more)

Nitrogen vacancy (NV) centers have been demonstrated as a useful tool in high pressure environments. However, the geometry and small working area of the diamond anvil cells (DACs) used to apply pressure present a challenge to effective delivery of microwave (mw) fields. We designed and characterized a novel slotted design for mw transmission to nitrogen-vacancy centers (NVs) in a diamond anvil cell via zero-field and in-field optically detected magnetic resonance (ODMR) measurements across pressures between 1 and 48 GPa. The mw fields experienced by NVs across the diamond culet was calculated from Rabi frequency and found to be higher and more uniform than those generated by an equivalent simple mw line, which will improve performance for wide-field, high-pressure measurements to probe spatial variations across samples under pressure.
Read the full abstract

All authors Timothy A. Elmslie, Luca Basso, Adam Dodson, Jacob Henshaw, Andrew M. Mounce

Quantum Physics

Experimental observation of dynamical blockade between transmon qubits via ZZ interaction engineering

Marco Riccardi, Aviv Glezer Moshe, Guido Menichetti et al. (+13 more)

We report the experimental realization of strong longitudinal (ZZ) coupling between two superconducting transmon qubits achieved solely through capacitive engineering. By systematically varying the qubit frequency detuning, we measure cross-Kerr inter-qubit interaction strengths ranging from 10 MHz up to 350 MHz, more than an order of magnitude larger than previously observed in similar capacitively coupled systems. In this configuration, the qubits enter a strong-interaction regime in which the excitation of one qubit inhibits that of its neighbor, demonstrating a dynamical blockade mediated entirely by the engineered ZZ coupling. Circuit quantization simulations accurately reproduce the experimental results, while perturbative models confirm the theoretical origin of the energy shift as a hybridization between the computational states and higher-excitation manifolds. We establish a robust and scalable method to access interaction-dominated physics in superconducting circuits, providing a pathway towards solid-state implementations of globally controlled quantum architectures and cooperative many-body dynamics.
Read the full abstract

All authors Marco Riccardi, Aviv Glezer Moshe, Guido Menichetti, Riccardo Aiudi, Carlo Cosenza, Ashkan Abedi, Roberto Menta, Halima Giovanna Ahmad, Diego Nieri Orfatti, Francesco Cioni, Davide Massarotti, Francesco Tafuri, Vittorio Giovannetti, Marco Polini, Francesco Caravelli, Daniel Szombati

Quantum Physics · Cross-listed from cs.IT

Convergence Properties of Good Quantum Codes for Classical Communication

Alptug Aytekin, Mohamed Nomeir, Lei Hu et al. (+1 more)

An important part of the information theory folklore had been about the output statistics of codes that achieve the capacity and how the empirical distributions compare to the output distributions induced by the optimal input in the channel capacity problem. Results for a variety of such empirical output distributions of good codes have been known in the literature, such as the comparison of the output distribution of the code to the optimal output distribution in vanishing and non-vanishing error probability cases. Motivated by these, we aim to achieve similar results for the quantum codes that are used for classical communication, that is the setting in which the classical messages are communicated through quantum codewords that pass through a noisy quantum channel. We first show the uniqueness of the optimal output distribution, to be able to talk more concretely about the optimal output distribution. Then, we extend the vanishing error probability results to the quantum case, by using techniques that are close in spirit to the classical case. We also extend non-vanishing error probability results to the quantum case on block codes, by using the second-order converses for such codes based on hypercontractivity results for the quantum generalized depolarizing semi-groups.
Read the full abstract

All authors Alptug Aytekin, Mohamed Nomeir, Lei Hu, Sennur Ulukus

Quantum Physics

Heat, work, and fluctuations in a driven quantum resonator

Riya Baruah, Pedro Portugal, Jun-Zhe Chen et al. (+2 more)

A central building block of a heat engine is the working fluid, which mediates the conversion of heat into work. In nanoscale heat engines, the working fluid can be a quantum system whose behavior and dynamics are non-classical. A particularly versatile realization is a quantum resonator, which allows for precise control and coupling to thermal reservoirs, making it an ideal platform for exploring quantum thermodynamic processes. Here, we investigate the thermodynamic properties of a driven quantum resonator whose temperature is controlled by modulating its natural frequency. We evaluate the work performed by the external drive and the resulting heat flow between the resonator and its environment, both within linear response and beyond. To further elucidate these processes, we determine the full distribution of photon exchanges between the resonator and its environment, characterized by its first few cumulants. Our results provide quantitative insights into the interplay between heat, work, and fluctuations, and may help in designing future heat engines.
Read the full abstract

All authors Riya Baruah, Pedro Portugal, Jun-Zhe Chen, Joachim Wabnig, Christian Flindt

Quantum Physics

Coupling free electrons to a trapped-ion quantum computer

Elias Pescoller, Santiago Beltrán-Romero, Sebastian Egginger et al. (+10 more)

Freely propagating electrons may serve as quantum probes that can become coherently correlated with other quantum systems, offering access to advanced metrological resources. We propose a setup that coherently couples free electrons in an electron microscope to a trapped-ion quantum processor, enabling non-destructive, quantum-coherent detection and the accumulation of information across multiple electrons. Our analysis shows that single electrons can induce resolvable qubit excitations, establishing a platform for practical applications such as quantum-enhanced, dose-efficient electron microscopy.
Read the full abstract

All authors Elias Pescoller, Santiago Beltrán-Romero, Sebastian Egginger, Nicolas Jungwirth, Martino Zanetti, Dominik Hornof, Michael S. Seifner, Iva Březinová, Philipp Haslinger, Thomas Juffmann, Johannes Kofler, Philipp Schindler, Dennis Rätzel

Quantum Physics

Noise-Robust Quantum-Inspired Synthetic Minority Oversampling for Condition Monitoring and Fault Classification in Industrial and Energy Systems

Amit S. Patel, Himanshukumar R. Patel, Bikash K. Behera et al. (+3 more)

Class imbalance remains a major challenge in industrial condition monitoring and fault classification, where minority fault patterns can be poorly represented during machine learning. This work develops a noise-aware quantum-inspired oversampling framework and systematically evaluates its effectiveness and robustness for industrial and energy-system fault diagnosis. The principal artificial-intelligence contribution is a noise-aware extension of the Quantum Synthetic Minority Oversampling Technique (QSMOTE), in which quantum-inspired perturbations are introduced directly into the compact-swap-test-based similarity estimation used during synthetic minority-sample generation. Consequently, noise propagates through overlap estimation and angle computation to the generated samples, enabling direct assessment of the robustness of the oversampling mechanism rather than perturbing only the downstream classifier. The engineering application is evaluated on four public datasets covering solar-panel faults, bearing condition monitoring, engine failures, and industrial fault detection. Five classical classifiers are used to compare performance on the original imbalanced data, after QSMOTE-based balancing, and under noisy-QSMOTE. The results show substantial classifier-dependent benefits from QSMOTE, including improvements of up to 170% on the engine-failure dataset and accuracy exceeding 0.99 on the industrial fault-detection dataset. Robustness experiments across six quantum-inspired noise channels further demonstrate that perturbations in similarity estimation can produce markedly different downstream effects depending on the noise model and classifier. The proposed framework therefore provides a reproducible approach for jointly assessing class-imbalance mitigation and noise robustness of quantum-inspired oversampling in practical industrial artificial-intelligence applications.
Read the full abstract

All authors Amit S. Patel, Himanshukumar R. Patel, Bikash K. Behera, Pranav Mehta, David Bassir, Ghanshyam G. Tejani

Quantum Physics

A matching decomposition algorithm for simulating quantum walk Hamiltonians

Mostafa Atallah, Alvin Gonzales, Daniel Dilley et al. (+3 more)

In this work, we present a new algorithm for generating quantum circuits that efficiently implement continuous time quantum walks on arbitrary simple sparse graphs. The algorithm, called matching decomposition, works by decomposing a continuous-time quantum walk Hamiltonian into a collection of exactly implementable Hamiltonians corresponding to matchings in the underlying graph followed by a novel graph compression algorithm that merges edges in the graph. We develop a greedy matching heuristic and a compression-aware matching heuristic, both of which can be used in the quantum circuit algorithm. Lastly, we convert the walks to a circuit and Trotterize over these components. The dynamics of the walker on each edge in the matching can be implemented in the circuit model as sequences of CX and CRx gates. We do not use Pauli decomposition when implementing walks along each matching. Furthermore, we compare greedy (compression-aware) matching decomposition to a standard Pauli-based simulation pipeline and find that greedy (compression-aware) matching decomposition consistently yields substantial resource reductions, requiring up to 43$\%$ (70%) fewer controlled gates and up to 54$\%$ (75%) shallower circuits than Pauli decomposition across multiple graph families. Finally, we also present examples and theoretical results for when matching decomposition can exactly simulate a continuous-time quantum walk on a graph.
Read the full abstract

All authors Mostafa Atallah, Alvin Gonzales, Daniel Dilley, Igor Gaidai, Zain H. Saleem, Rebekah Herrman

Quantum Physics

Quantum-enhanced optimization for patient stratification in clinical trials

Laia Domingo and Christine Johnson

Clinical trials are notorious for their high failure rates and steep costs, leading to wasted time and resources spend, prolonged development timelines, and delayed patient access to new therapies. A key contributor to these failures is biological uncertainty, which complicates trial design and weakens the ability to detect true treatment effects. In particular, inadequate patient stratification often results in covariate imbalances across treatment arms, masking treatment effects and reducing statistical power, even when therapies are effective for specific patient subpopulations. This work presents an optimization-based, quantum-enhanced approach to patient stratification that explicitly minimizes covariate imbalance across numerical and categorical variables, without altering protocol design or trial endpoints. Using real clinical trial data, we demonstrate that hybrid quantum-classical optimization methods achieve high-quality stratification while scaling efficiently to larger cohorts. In our benchmark study, the quantum-enhanced pipeline delivered over a 100x improvement in computational efficiency compared to classical approaches, enabling faster iteration and practical deployment at scale. This report shows how improved stratification can lead to decision-relevant gains, including up to a fivefold increase in statistical significance in treatment effect estimation, reducing treatment-effect dilution and increasing trial sensitivity. Together, these results show that optimization-driven stratification can strengthen clinical trial design, improve confidence in downstream decisions, and reduce the risk of costly late-stage failure.
Read the full abstract

Quantum Physics

Transmon Architecture for Emission and Detection of Single Microwave Photons

Daniel L. Campbell, Stephen McCoy, Melinda Andrews et al. (+12 more)

We develop a compact transmon emitter/detector (TED) superconducting circuit and demonstrate its dual functionality as a single-photon source and detector. In our setup, photons emitted by a source TED are transmitted via a meter-long coaxial cable, routed through a circulator, and captured by a measurement TED. Both TED modules operate with nominally identical parameters, highlighting the flexibility of this novel architecture. Furthermore, we introduce an efficient microwave photon detection scheme tailored to the TED. Using this setup, we detect 60% of the emitted Fock state photons and infer a 95% detection efficiency at the input of the measurement TED, which we calibrate against coherent state measurements. The reset and photon emission/detection processes each require approximately $2\,\mu s$, yielding a minimum protocol duration of $4\,\mu s$ as constrained by our chosen TED parameters. Ultimately, the TED demonstrates a new use case for the recently developed double transmon coupler (DTC): a compact, drop-in, tunable, and transition-selective link between a coherent data transmon and a waveguide. Circuits like the TED will play a vital role in quantum information processing by facilitating unconditional fast reset, enabling microwave photon metrology, and serving as nascent quantum communication interfaces (QCIs). QCIs mediate entanglement distribution between quantum processing units (QPUs) within a cryostat or interface with microwave-to-optical transducers for long-range quantum networking.
Read the full abstract

All authors Daniel L. Campbell, Stephen McCoy, Melinda Andrews, Alexander Madden, Viva R. Horowitz, Bakir Husremović, Samuel Marash, Christopher Nadeau, Man Nguyen, Andrew M. Brownell, Derrick Sica, Michael Senatore, Samuel Schwab, Erin Sheridan, Matthew D. LaHaye

Quantum Physics

No quantum solutions to linear constraint systems from monomial measurement-based quantum computation in odd prime dimension

Markus Frembs, Cihan Okay and Ho Yiu Chung

We combine the study of resources in measurement-based quantum computation (MBQC) with that of quantum solutions to linear constraint systems (LCS). Contextuality of the input state in MBQC has been identified as a key resource for quantum advantage, and in a stronger form, underlies algebraic relations between (measurement) operators which obey classically unsatisfiable (linear) constraints. Here, we compare these two perspectives on contextuality, and study to what extent they are related. More precisely, we associate a LCS to certain MBQC which exhibit strong forms of state-dependent contextuality, and ask if the measurement operators in such MBQC give rise to state-independent contextuality in the form of quantum solutions of its associated LCS. Our main result rules out such quantum solutions for a large class of MBQC. This both sharpens the distinction between state-dependent and state-independent forms of contextuality, and further generalises results on the non-existence of quantum solutions to LCS in finite odd (prime) dimension.
Read the full abstract

Quantum Physics · Cross-listed from physics.ins-det

Nanofabricated torsion pendulums for tabletop gravity experiments

Jack Manley, Charles A. Condos, Zachary Fegley et al. (+5 more)

Measurement of mutual gravitation on laboratory scales is an outstanding challenge and a prerequisite to probing theories of quantum gravity. A leading technology in tabletop gravity experiments is the torsion balance, with limitations due to thermal decoherence. Recent demonstrations of lithographically defined suspensions in thin-film silicon nitride with macroscale test masses suggest a path forward, as torsion pendulums dominated by gravitational stiffness may achieve higher mechanical quality factors through dilution of material losses. Here we demonstrate a 250 micron by 5 mm by 1.8 micron torsion fiber supporting 87 grams and forming a Cavendish-style torsion pendulum with tungsten test masses that – to our knowledge – is the largest thin-film silicon-nitride-based oscillator to date. Torsion pendulums with thin-film, nanofabricated suspensions provide a test bed for near-term tabletop experiments probing classical and quantum gravitational interaction between oscillators.
Read the full abstract

All authors Jack Manley, Charles A. Condos, Zachary Fegley, Gayathrini Premawardhana, Thomas Bsaibes, Jacob M. Taylor, Dalziel J. Wilson, Jon R. Pratt

Quantum Physics

Skyrmion Quantum Diode Prototype: Bridging Micromagnetic Simulations and Quantum Models

Haowen Yang, Gerald Bissell, Han Zhong et al. (+4 more)

Magnetic skyrmions are topologically protected spin textures known for their robustness against perturbations. Their topological stability makes them robust information carriers, ideal for tackling a key challenge in quantum computing: creating reliable, one-way links between different types of qubits. In this proof-of-concept study, we introduce a novel device - the skyrmion quantum diode - based on skyrmion qubits. Our approach combines classical micromagnetic simulations, achieving skyrmion diameters as small as 3 nm, with quantum circuit models inspired by superconducting qubits. In this work, we demonstrate: (i) unidirectional skyrmion transport via the skyrmion Hall effect in asymmetric junctions, spanning length scales from 20 nm down to 3 nm; (ii) potential compatibility with flux-tunable quantum architectures; and (iii) preliminary insights into anharmonicity in skyrmion-based qubit systems. These results establish both the operational feasibility and the scaling behavior necessary for a hybrid skyrmion-quantum platform. Our work outlines a path toward integrating skyrmion based quantum components into practical device architectures, enabling low-dissipation, unidirectional quantum information transport. This capability is crucial for scalable quantum computing, spintronic logic, and hybrid quantum systems, and opens opportunities for chipscale, pump-free isolators and directional quantum links that enhance readout fidelity, reduce cryogenic load, and support modular skyrmion-superconducting processors
Read the full abstract

All authors Haowen Yang, Gerald Bissell, Han Zhong, Peter Van Kirk, Tiger Cao, Pengcheng Lu, Yingying Wu

Quantum Physics

Dressed-state relaxation in coupled qubits as a source of two-qubit gate errors

Ruixia Wang, Jiayu Ding, Chenlu Wang et al. (+8 more)

Understanding error mechanisms in two-qubit gate operations is essential for building high-fidelity quantum processors. While prior studies predominantly treat dephasing noise as either Markovian or predominantly low-frequency, realistic qubit environments exhibit structured, frequency-dependent spectra. Here we demonstrate that noise at frequencies matching the dressed-state energy splitting–set by the inter-qubit coupling strength g–induces a distinct relaxation channel that degrades gate performance. Through combined theoretical analysis and experimental verification on superconducting qubits with engineered noise spectra, we show that two-qubit gate errors scale predictably with the noise power spectral density at frequency 2g, extending the concept of $T_{1\rho}$ relaxation to interacting systems. This frequency-selective relaxation mechanism, universal across platforms, enriches our understanding of decoherence pathways during gate operations. The same mechanism sets coherence limits for dual-rail or singlet-triplet encodings.
Read the full abstract

All authors Ruixia Wang, Jiayu Ding, Chenlu Wang, Yujia Zhang, He Wang, Wuerkaixi Nuerbolati, Zhen Yang, Xuehui Liang, Weijie Sun, Haifeng Yu, Fei Yan