Quantum Many-Body System Correlation Analysis

A recent preprint from the STFC Hartree Centre, IBM, and the University of Oxford, demonstrates the preparation of symmetry-protected topological (SPT) order across 100 qubits on an IBM Heron quantum processor. https://lnkd.in/eedFR7u5 Using a hybrid quantum-classical workflow that combines DMRG with tensor network based adaptive quantum compilation (AQC) techniques, the authors show that the ground state of the Haldane phase can be prepared at utility scale with key topological properties intact. They probe both non-local string order and the characteristic entanglement spectrum degeneracy, and observe robust signatures even without error mitigation. With zero-noise extrapolation (ZNE) applied, the measured diagnostics show excellent agreement with tensor-network predictions. More broadly, this is a strong example of quantum-centric workflows in action, combining tensor-network methods with quantum processors to prepare and validate nontrivial many-body states at scale, and laying the groundwork for studying the dynamics of exotic phases of matter in classically challenging regimes. Together, these advances highlight yet another powerful example of how IBM quantum processors can drive scientific exploration and discovery.

DISSIPATIVE CONTINUOUS TIME CRYSTALS IN TENGENA's QUANTUM-SCALE PLATFORM The spontaneous breaking of continuous time-translational symmetry in open quantum systems represents a frontier in nonequilibrium physics with direct implications for quantum-scale architectures. Within Tengena’s platform, engineered to synthesize quantum transport, photonic control, and correlation-driven dynamics, the emergence of quantum continuous time crystals (qCTCs) offers a novel mechanism for persistent temporal coherence and signal routing without external modulation. Recent simulations of spin-1 lattices with finite-range interactions reveal two distinct qCTC phases: qCTC-I: A fluctuation-resilient phase consistent with classical limit-cycle dynamics but stabilized under quantum corrections. qCTC-II: A correlation-induced phase absent in mean-field theory, characterized by nontrivial scaling of quantum fluctuations and emergent oscillations in absence of long-range order. These phases are robust to local decay and perturbations, and critically, they do not rely on symmetry constraints in the master equation. The simulation also reveals a formation mechanism for continuous quantum time crystals: quantum correlations between particles, previously regarded as disruptive to time-crystalline order, are shown to play a stabilizing role. These correlations enable the emergence of persistent oscillations even in regimes where mean-field theory fails, underscoring the fundamentally non-classical nature of the observed phases. The system exhibits collective dynamics that cannot be reduced to single-particle behavior. The temporal ordering arises from many-body interactions that drive the system toward a self-organized oscillatory state. This marks a paradigm shift from externally controlled photonic or quantum logic routing to architectures based on intrinsic dynamical self-organization, aligning directly with Tengena’s vision for autonomous quantum subsystems. The qCTC-II phase is particularly aligned with Tengena’s goals in low-dissipation quantum signaling, as it forms an approximate dark state with minimal intermediate-state population. Oscillations are confined between |↓⟩ and |↑⟩ states, suppressing heating and decoherence—key for scalable quantum memory and photonic switching. The model maps directly onto neutral-atom arrays, with Rabi frequencies (~13 MHz) and dipole-dipole interaction strengths (~2.6 MHz) achievable via off-resonant microwave dressing of Rydberg states. These parameters are compatible with Rubidium-based platforms already under consideration for Tengena’s prototyping. Strategically, integrating qCTC dynamics into Tengena’s platform enables: temporal coherence without external clocks, reducing control overhead; correlation-driven phase stability, enhancing fault tolerance in quantum logic; and modular subsystems that self-organize as a resource, not a constraint for hybrid quantum-photonic chips. # DOI: https://lnkd.in/eh92Ujdh

Krylov quantum diagonalization and many-body quantum computing In computational quantum sciences—particularly within quantum chemistry, condensed matter physics, and high-energy physics—the precise calculation of ground-state energies of quantum many-body systems remains foundational yet challenging. Traditional quantum computational approaches to address these challenges primarily include Quantum Phase Estimation (QPE) and the Variational Quantum Eigensolver (VQE). Quantum Phase Estimation (QPE) is theoretically robust, offering precision guarantees for eigenstate estimation. However, it relies heavily on fault-tolerant quantum computing, currently restricting its practical use to smaller-scale problems due to significant circuit depth and error-correction requirements. Conversely, the Variational Quantum Eigensolver (VQE) has emerged as a prominent heuristic for near-term, pre-fault-tolerant quantum processors, demonstrating viability in various small-scale experimental settings. Its iterative nature, however, poses difficulties for scaling, often hindering practical large-scale implementations. In this context, the recent paper by Yoshioka and coauthors, published in Nature Communications (link below), introduces a significant alternative known as Krylov Quantum Diagonalization (KQD). KQD effectively bridges the gap between the theoretical robustness of QPE and the near-term practicality of VQE by employing a Krylov subspace approach—a concept familiar from classical linear algebra—within a quantum computational framework. The authors have successfully demonstrated KQD’s scalability through implementations on superconducting quantum processors, addressing systems with up to 56 qubits. This achievement represents a substantial advancement over the typical capabilities of current pre-fault-tolerant devices. By constructing Krylov subspaces through time evolutions of initial states directly executed on quantum hardware, followed by classical diagonalization, the method significantly reduces classical memory requirements. This hybrid quantum-classical strategy addresses critical bottlenecks inherent to classical large-scale diagonalization methods. Importantly, KQD exhibits exponential convergence toward ground-state energy estimates, demonstrating notable resilience against noise. Although quantum processor noise remains a challenge, advanced error mitigation techniques showcased in the study reinforce the method's practical potential within the current noisy intermediate-scale quantum (NISQ) era. Paper by Yoshioka and coauthors: https://lnkd.in/dSXvbNTU #QuantumComputing #QuantumPhysics #KrylovDiagonalization #QuantumAlgorithms #ComputationalQuantumScience #QuantumManyBodySystems #QuantumChemistry #CondensedMatterPhysics #QuantumPhaseEstimation #VariationalQuantumEigensolver #NISQ #ResearchInnovation #AcademicDiscussion #ScientificAdvancement #NatureCommunications

Our work "Generation and Read-Out of Many-Body Bell Correlations with a Probe Qubit" freshly published in Physical Review Letters https://lnkd.in/dJfZVqUG As quantum systems scale, verifying entanglement and Bell correlations becomes increasingly difficult. We wanted to find a efficient way to handle this certification. TL;DR: We demonstrate that you only need a single probe qubit interacting with an N-qubit system to get the job done. The probe qubit acts as both the catalyst to induce many-body correlations and the diagnostic tool to read them out. By measuring just this one qubit coherence dynamics, we can efficiently certify complex multipartite entanglement, and many-body Bell correlations. #quantumtechnolgies #quantuinformation #quantumcorrelations #quantumsimulations