Quantum Computing
Core quantum computing developments, breakthroughs, and innovations
quantum-computingHeart Simulations Now Run Rapidly Thanks to New AI-Powered Modelling Technique
Researchers are tackling the computational burden of simulating left ventricular (LV) mechanics, a crucial aspect of understanding cardiac function and planning interventions. Siyu Mu, Wei Xuan Chan, and Choon Hwai Yap, all from the Department of Bioengineering at Imperial College London, alongside et al., have developed CardioGraphFENet, a novel graph-based surrogate model that rapidly estimates full-cycle LV myocardial biomechanics. This work represents a significant advance because existing graph surrogates lack full-cycle prediction, and physics-informed methods often fail with complex heart shapes. By integrating a global-local graph encoder, a temporal encoder, and a cycle-consistent bidirectional formulation, CardioGraphFENet achieves high fidelity to traditional finite-element analysis while requiring substantially less computational power and supervisory data. Conventional finite-element analysis, while valuable for understanding cardiac function and planning clinical interventions, is computationally demanding and limits patient-specific modelling. Current graph-based surrogates lack full-cycle prediction capabilities, and physics-informed neural networks often struggle with the complexities of cardiac geometries. This new framework addresses these limitations by integrating a global-local graph encoder, a gated recurrent unit-based temporal encoder, and a cycle-consistent bidirectional formulation. The research team’s approach leverages a large dataset of finite-element analysis simulations to train the model, enabling high-fidelity predictions that align with traditional FEA ground truths. CGFENet captures mesh features using weak-form-inspired global coupling and models cycle-coherent dynamics conditioned on the target volume-time signal. Crucially, the cycle-consistency strategy significantly reduces the need for extensive FEA supervision while maintaining accuracy. This allows for efficient and reliable estimation of myocardial biomechanics across div
Quantum ZeitgeistLoading...0
quantum-computingBlack Hole Maths Unlocks Secrets of How Energy Flows in Exotic Matter
Scientists have investigated shear mode transport coefficients arising from gravitational perturbations around anti-de Sitter black branes, revealing a surprising connection to multiple polylogarithms. Paolo Arnaudo from the University of Southampton, alongside colleagues, detail an analytical study extending previous work to higher orders and dimensions. Their calculations, performed within a five-dimensional black hole background up to order, characterise the mathematical structure of these transport coefficients and provide a more complete understanding of strongly coupled systems like Super Yang-Mills theory. This research significantly advances the field by offering a robust framework for analysing transport phenomena in these complex gravitational settings. Holographic calculation of shear viscosity in strongly coupled gauge theories Scientists have achieved a significant advance in understanding the behaviour of strongly coupled quantum field theories through detailed analysis of gravitational perturbations. This work presents an analytical study of transport coefficients associated with shear forces around black branes in anti-de Sitter space, revealing a mathematical structure fully described by multiple polylogarithms. Researchers focused on computing these transport coefficients for N = 4 super Yang-Mills theory, extending previous results to order q10 in a five-dimensional black hole background. The study not only refines calculations within this established framework but also generalises the procedure to d + 1 dimensions, characterising the mathematical form of the resulting transport coefficient expressions. This breakthrough builds upon the holographic duality, a concept linking gravity and quantum field theory, to probe the non-equilibrium dynamics of strongly interacting systems. By examining gravitational perturbations around black brane backgrounds, the research decodes the dissipative and hydrodynamic responses of the boundary theory. The solutio
Quantum ZeitgeistLoading...0
quantum-computingQuantum AI Shortcut Could Speed up Language Models with Reduced Complexity
Scientists are developing novel methods to improve sequence prediction, a crucial task in areas such as natural language processing and dynamical systems modelling. Alessio Pecilli and Matteo Rosati, both from the Dipartimento di Ingegneria Civile, Informatica e delle Tecnologie Aeronautiche at the Universit`a degli Studi Roma Tre, alongside et al., present a variational implementation of self-attention, termed Quantum Attention by Overlap Interference (QSA), which leverages quantum principles to predict future sequence elements. This research is significant because QSA achieves nonlinearity through state overlap interference and directly calculates a loss function as an observable expectation value, circumventing conventional decoding processes. Moreover, the team demonstrates that QSA exhibits potentially advantageous computational scaling compared to classical methods and successfully learns sequence prediction from both classical data and complex many-body quantum systems, establishing a trainable attention mechanism for dynamical modelling. Quantum self-attention via direct Renyi-1/2 entropy measurement Scientists have developed a novel quantum self-attention mechanism, termed QSA, that directly addresses computational bottlenecks within transformer architectures and large language models. This breakthrough focuses on the core self-attention operation, crucial for predicting sequential data by weighting combinations of past information. Unlike previous quantum approaches, the research realizes necessary non-linearity through interference of quantum state overlaps, directly translating a Renyi-1/2 cross-entropy loss into an expectation value measurable as an observable. This innovative design bypasses the need for complex decoding processes typically required to convert quantum predictions into classical outputs, streamlining the training procedure. Furthermore, the QSA naturally integrates a trainable data-embedding, establishing a direct link between quantum s
Quantum ZeitgeistLoading...0
quantum-computingNew Technique Unlocks Key to Simulating Complex Molecular Behaviour Accurately
Researchers continue to grapple with the long-standing N-representability problem for reduced density matrices, a critical issue within electronic structure theory. Ofelia B. Oña from the Universidad Nacional de La Plata, alongside Gustavo E. Massaccesi and Pablo Capuzzi from the Universidad de Buenos Aires, and et al., present a novel framework for determining ensemble N-representability of p-body matrices. Building upon their previous work utilising adaptive derivative-assembled pseudo-Trotter methods, this study introduces a purification strategy that embeds ensemble states into pure states, enabling assessment via minimisation of the Hilbert-Schmidt distance. This methodology not only allows for the correction of defective density matrices but also offers a pathway for robust state reconstruction, representing a significant advance in density-matrix refinement and validation through numerical simulations on systems ranging from two to four electrons. This breakthrough addresses a critical gap in existing methodologies, which largely focus on pure-state representability while overlooking the importance of ensemble states in diverse applications such as thermal mixtures and open quantum systems. The research introduces a purification strategy, embedding an ensemble state into a pure state defined on an extended Hilbert space, ensuring identical reduced density matrices for both states. By iteratively applying unitaries to an initial purified state, the algorithm minimizes the Hilbert-Schmidt distance between its p-body reduced density matrix and a specified target matrix, effectively gauging the N-representability of the target. This methodology not only assesses whether a given matrix corresponds to a physically valid N-electron state, but also facilitates the correction of defective ensemble reduced density matrices and enables quantum-state reconstruction for density-matrix refinement. The core of the work builds upon a previously established pure-state algorit
Quantum ZeitgeistLoading...0
quantum-computingSupernova Remnant’s Plasma Mapped in Detail, Revealing Explosion’s Inner Workings
Scientists investigating young supernova remnants have long sought to map the properties of their shocked plasma to reveal details of the explosion process and ejecta structure. Manan Agarwal, Jacco Vink, and Liyi Gu, alongside colleagues including Paul P. Plucinsky and Aya Bamba, present the first plasma parameter maps of a supernova remnant, Cassiopeia A, obtained using high-resolution observations from the XRISM/Resolve microcalorimeter. Their analysis, conducted via a novel Bayesian framework called UltraSPEX, details significant variations in elemental abundance ratios and Doppler velocities within Cas A, suggesting substantial clumping of the ejecta and providing crucial constraints on reverse-shock velocities. These findings represent a substantial advance in our understanding of core-collapse supernovae and the complex physics governing their evolution. UltraSPEX couples the SPEX plasma code with the UltraNest nested-sampling algorithm, allowing for robust inference of plasma parameters and a thorough exploration of potential uncertainties. Key findings demonstrate enhanced abundance ratios of Argon to Silicon and Calcium to Silicon near the base of the prominent Si-rich jets emanating from the remnant. A notably high Nickel to Iron mass ratio of 0.08 ±0.015 was identified in the base of the northeast jet, suggesting unique nucleosynthetic processes occurred during the supernova explosion. Analysis of the ejecta reveals that iron-group elements exhibit systematically higher Doppler velocities and broadenings compared to intermediate-mass elements across most regions, with maximum differences reaching approximately 800km/s and 1200km/s respectively. Furthermore, Calcium displays distinct and faster kinematics than other intermediate-mass elements in several southeastern regions of the remnant. A robust anti-correlation between ionization timescale and electron temperature, particularly for iron-group elements, was observed, and can be explained by models inco
Quantum ZeitgeistLoading...0
quantum-computingMolecular Chaos Mapped with New Diagrams Reveals Hidden Order in Potassium Cyanide
Scientists have long sought to understand the complex vibrational behaviour of highly nonlinear molecules, and a new study utilising variable parameter correlation diagrams offers significant insight into these systems. H. Párraga, F. J. Arranz, and R. M. Benito, alongside F. Borondo et al., demonstrate the utility of this approach by examining the vibrational spectrum of potassium cyanide (K-CN). Their research reveals how classical structures, specifically Kolmogorov-Arnold-Moser tori, manifest as emerging diabatic states within the correlation diagrams, a phenomenon obscured by conventional constant-Planck analyses. This methodology successfully unveils a transition from order to chaos, presenting it as a frontier of scarred functions and providing a novel means of characterising molecular dynamics. This technique reveals hidden classical structures, specifically Kolmogorov-Arnold-Moser tori, as emerging diabatic states in the quantum levels correlation diagram, structures that would otherwise remain obscured when using a fixed value for Planck’s constant. The research focuses on the K-CN molecule, a system known for its complex and chaotic dynamics, and demonstrates a pathway to understanding the transition from order to chaos through the identification of a frontier of scarred functions. The work builds upon established correlation diagrams, traditionally used to rationalize molecular rovibrational states based on real-valued parameters like geometrical distances or angles. Instead, researchers artificially varied the Planck constant, ħ, to effectively implement a microscopic lens focusing on classical regular structures embedded within chaotic regions of the molecular phase space. By reducing ħ, quantum states are confined to smaller phase space volumes, allowing for detailed examination of their dynamical characteristics within the regular classical region. This approach provides a unique perspective on the interplay between quantum and classical behaviour in
Quantum ZeitgeistLoading...0
quantum-computingThe final magnet for the High-Luminosity upgrade of the Large Hadron Collider leaves Berkeley Lab
Key Takeaways The final superconducting magnet built in the U.S. for the high-luminosity upgrade to the Large Hadron Collider (LHC) has left Berkeley Lab on its way to CERN for the first stage of its journey. These so-called quadrupole magnets, which focus the particle beams, will, for the first time, use superconducting niobium-tin cables to produce stronger magnetic fields, resulting in more tightly focused beams and higher collision rates in the LHC, thereby improving experiments and broadening research opportunities. Multiple national laboratories collaborated to design and build these advanced magnets, with a team from Berkeley Lab winding the superconducting wire into cables and then assembling the coiled cables into the quadrupole magnets. The last of 21 new superconducting quadrupole magnets for the High-Luminosity Large Hadron Collider Accelerator Upgrade Project, or HL-LHC AUP, has left the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) for testing before shipment to CERN in Switzerland for installation in the LHC, the world’s most powerful particle collider. These advanced magnets use niobium-tin (Nb3Sn) superconducting cables to generate magnetic fields much higher than those of existing magnets. It will be the first time such magnets are used in a particle accelerator, enhancing the LHC’s capabilities to advance fundamental research and enable new discoveries in high-energy physics and related fields. The magnets are the result of over twenty years of dedicated R&D in Nb3Sn technology and reflect the combined efforts of scientists, engineers, technicians, and operations staff from CERN and four U.S. national laboratories: Berkeley Lab, Brookhaven National Laboratory (Brookhaven Lab), Fermi National Accelerator Laboratory (Fermilab), and the National High Magnetic Field Laboratory at Florida State University. “This outstanding achievement is a testament to the hard work and successful collaboration between expe
Fermilab QuantumLoading...0
quantum-computingClassical Physics Paradox Solved Without Relying on Quantum Assumptions
Scientists have long grappled with the Gibbs paradox, a fundamental issue in classical statistical mechanics traditionally addressed by the 1/N!. correction to account for particle indistinguishability. Zheng Zhang from Lanzhou University of Technology and Zheng Zhang from The University of Hong Kong, with colleagues, now offer a novel resolution of this paradox within a purely classical framework, bypassing the need for this conventional correction. Their research, detailed in a recent letter, demonstrates that the paradox dissolves when considering only the equal probability principle and reinterpreting Gibbs entropy as Shannon entropy, a measure of our lack of information rather than system disorder. This informational perspective not only resolves the paradox but also clarifies the relationship between entropy and extractable work during gas mixing, potentially reshaping our understanding of entropy’s role in statistical mechanics. This work presents a novel resolution relying solely on the equal probability principle inherent in classical ensemble theory, eliminating the need for the 1/N. correction. The researchers interpret the Gibbs entropy as Shannon entropy, quantifying ignorance rather than disorder, offering a fundamentally informational perspective on the paradox. This approach clarifies the connection between information and extractable work during gas mixing processes, demonstrating that the apparent paradox arises from a misunderstanding of information loss. The Gibbs paradox emerges when applying classical ensemble theory to ideal gases, resulting in a non-extensive entropy that leads to paradoxical consequences when considering the mixing of identical gases. Traditionally, this has been resolved by incorporating quantum mechanics and the 1/N. correction to restore entropy extensivity. However, this study demonstrates that maintaining the equal probability principle rigorously avoids the paradox, even in regimes where quantum effects are negligible.
Quantum ZeitgeistLoading...0
quantum-computingQuantum Systems Obey Thermodynamics’ Second Law Even When Appearing Perfectly Ordered
Scientists are increasingly investigating the applicability of thermodynamics to quantum systems, and a new study by Yuuya Chiba (RIKEN Hakubi Research Team), Yasushi Yoneta (RIKEN, Center for Quantum Computing), and Ryusuke Hamazaki et al. from RIKEN and The University of Tokyo/Osaka addresses a long-standing problem reconciling the second law of thermodynamics with quantum mechanics in closed systems. The research demonstrates that the second law can emerge even from pure quantum states by defining a novel framework based on infinite-observable macroscopic thermal equilibrium and macroscopic operations. This work is significant because it establishes two distinct forms of the second law, utilising reasonable macroscopic criteria for observables, equilibrium states and operations, and offers insights into the timescales governing these quantum thermodynamic processes. Recent research demonstrated that even pure quantum states can accurately represent thermal equilibrium, yet these states traditionally violate the second law due to their potential to generate work under arbitrary conditions. This work addresses the emergence of the second law for adiabatic operations, constrained state transitions in closed systems, by introducing the concept of infinite-observable macroscopic thermal equilibrium (iMATE). A quantum state is considered to be in iMATE if its expectation values for all additive observables align with their established equilibrium values. Researchers developed a macroscopic operation defined as unitary evolution driven by a time-dependent additive Hamiltonian, mirroring adiabatic operations in thermodynamics. Employing these concepts, the study proves that no extensive work can be extracted from any state in iMATE through these macroscopic operations, provided the operation times are independent of system size. Furthermore, a quantum-mechanical form of entropy density was introduced, aligning with thermodynamic entropy density for any state representing
Quantum ZeitgeistLoading...0
quantum-computingQuantum Communication Secured by Choosing Measurement Basis Offers Ultimate Privacy
Scientists have developed a novel protocol for one-way quantum secure direct communication, utilising the choice of measurement basis as the secret key. Santiago Bustamante and Boris A. Rodríguez, both from Universidad de Antioquia, alongside Elizabeth Agudelo of TU Wien, demonstrate a system where information is encoded and decoded through measurements performed in either the computational or Hadamard basis. This research is significant because it establishes information-theoretic security against BB84-symmetric attacks using finite ensembles of entangled pairs and a public channel. Importantly, the protocol requires no local unitary operations by the receiver, making it particularly suitable for practical implementation in network configurations such as star networks. This research addresses the fundamental question of distinguishing ensembles described by identical compressed density operators and introduces a method for encoding and decoding classical information through measurements in either the computational or Hadamard basis. Employing quantum wiretap channel theory, the study rigorously assesses the secure net bit rates and certifies the information-theoretic security of various implementations against BB84-symmetric attacks. A key advantage of this model is the elimination of local unitary operations required by the receiver, making it particularly suitable for practical implementation in star network configurations. The work builds upon the concept of finite ensembles of entangled EPR pairs, each shared between two parties, Alice and Bob, and explores how local measurements influence the transmission of a single bit of information. Researchers define a compressed density operator as the state of an average entity within an ensemble, acknowledging that this operator may not fully capture all information about the ensemble’s preparation. By measuring qubits in either the computational or Hadamard basis, Alice and Bob induce correlated collapses in their res
Quantum ZeitgeistLoading...0
quantum-computingQuantum Compilation Speeds up 100x, Bringing Practical Quantum Computers Closer
Researchers are tackling the challenge of efficiently translating complex quantum algorithms into instructions for near-term quantum hardware. Aaron Hoyt from University of Washington and Pacific Northwest National Laboratory, alongside Meng Wang and Fei Hua from Pacific Northwest National Laboratory, et al., present QASMTrans, a novel end-to-end quantum compilation framework designed for just-in-time deployment. This work is significant because QASMTrans achieves over 100x faster compilation speeds than existing tools like Qiskit on certain circuits, while maintaining comparable fidelity and uniquely offering direct integration with hardware control systems via pulse generation. By bridging the gap between logical circuits and physical implementation, and incorporating noise-aware optimisation and circuit space sharing, QASMTrans facilitates the development and execution of real-time adaptive quantum algorithms on current quantum processing units. Rapid Quantum Circuit Transpilation via Pulse-Level Gate Set Optimisation Scientists have unveiled QASMTrans, a high-performance quantum compiler designed to rapidly translate abstract quantum algorithms into device-specific control instructions. This C++-based framework achieves over 100x faster compilation than existing tools like Qiskit for certain circuits, enabling the transpilation of large, complex circuits in a matter of seconds. QASMTrans distinguishes itself by offering complete, end-to-end device-pulse compilation and direct integration with quantum control systems such as QICK, effectively bridging the gap between logical circuits and the underlying hardware. The research focuses on accelerating the process of transpilation, which converts high-level quantum circuits into a format compatible with the limitations of near-term quantum devices. By employing latency-aware Application-tailored Gate Sets at the pulse level, QASMTrans identifies critical sequences within a circuit and generates optimized pulse schedu
Quantum ZeitgeistLoading...0
quantum-computingQuantum Entanglement’s ‘no Signalling’ Rule Bends, but Doesn’t Break
Scientists are increasingly scrutinising the no-signalling principle, a cornerstone of Bell inequality and steering experiments, as experimental flaws can mimic violations beyond statistical fluctuations. Lucas Maquedano (Federal University of Paraná), Sophie Egelhaaf (University of Geneva), and Amro Abou-Hachem (Lund University, with et al. including Jef Pauwels and Armin Tavakoli) present extensions to local hidden variable and local hidden state theories, accommodating quantifiable signalling. Their research develops non-classicality tests applicable to these extended models, utilising both complete statistical analysis and corrections to established Bell and steering inequalities. This work is significant because it addresses apparent signalling in realistic scenarios, specifically demonstrating its applicability to data arising from processor imperfections and inefficient detectors. These violations, previously attributed to statistical fluctuations, can arise from subtle systematic effects present in realistic experimental setups. The work introduces extensions to local hidden variable and local hidden state theories, allowing for bounded and quantifiable amounts of signalling between entangled particles. This approach moves beyond simply enforcing no-signalling through data post-processing, instead explicitly relaxing classical models to incorporate a measurable signalling parameter. The study establishes methods for developing non-classicality tests applicable to these extended models, utilising both exact calculations based on complete statistical data and corrections to standard Bell and steering inequalities. These techniques were demonstrated using two scenarios known to exhibit apparent signalling: data obtained from an IBM quantum processor and post-selected data originating from inefficient detectors. By quantifying the permissible signalling, the research provides a means to distinguish genuine quantum non-classicality from artefacts introduced by ex
Quantum ZeitgeistLoading...0