Quantum Simulation Reveals Curved Spacetime on 80 Qubits

Scientists are increasingly exploring the intersection of quantum mechanics and general relativity, and a new study details the observation of quantum many-body dynamics within emergent curved spacetime. Brendan Rhyno, Bastien Lapierre, and Smitha Vishveshwara from the Department of Physics at the University of Illinois at Urbana-Champaign, working with Khadijeh Najafi from IBM Quantum and IBM T.J.

Watson Research Center, and Ramasubramanian Chitra from the Institute for Theoretical Physics at ETH Zurich, demonstrate this phenomenon using 80 superconducting qubits on Heron processors.

This research, a collaborative effort between institutions in the United States and Switzerland, is significant because it establishes large-scale digital processors as a platform for investigating many-body dynamics in synthetic, tunable curved spacetimes, allowing observation of effects like curved light-cone propagation and horizon-induced freezing. Researchers have demonstrated a novel way to model complex physical phenomena using quantum computers. The work creates artificial versions of warped spacetime, similar to that around black holes, within a programmable processor. This advance promises to unlock new insights into areas ranging from cosmology to condensed matter physics. Researchers are now using quantum processors to model the behaviour of matter in curved spacetime, a fundamental aspect of gravity and cosmology. This work demonstrates how 80 superconducting qubits on IBM Heron processors can digitally simulate complex quantum dynamics within artificially created curved spaces. By carefully engineering the interactions between these qubits, the team realised excitations that behave as if moving along curved paths dictated by an effective metric. Following a disturbance to the system, a ‘quench’, they observed phenomena mirroring those predicted by theories of curved spacetime, including distorted light-cone propagation and a freezing of magnetization near simulated horizons. Despite the strong spatial variations introduced into the system, the qubits exhibited ballistic propagation of quasiparticles, suggesting a surprising level of order within the simulated curvature. These findings establish large-scale digital quantum processors as a versatile tool for exploring many-body dynamics in tunable, synthetic curved spacetimes, opening new avenues for understanding the interplay between quantum mechanics and gravity. Once a theoretical concept confined to mathematical models, simulating curved spacetime is now becoming experimentally accessible through quantum technology. At the heart of this research lies the ability to control the interactions between qubits to mimic the effects of gravity on quantum particles.

The team achieved this by manipulating the couplings within a spin-1/2 XXZ chain, a standard model in quantum physics, and tailoring it to resemble a Tomonaga-Luttinger liquid, a theoretical description of interacting electrons in one dimension. This careful design allowed them to create an effective metric, defining the geometry within which the qubits operate. Beyond simply creating a curved space, the researchers were able to observe how quantum information propagates within it, revealing behaviours consistent with theoretical predictions. This digital platform allows for precise control over the effective spacetime metric, enabling the creation of complex geometries and systematic exploration of their impact on quantum dynamics. The observed robustness of these simulations, maintaining clear signals for up to 20 computational steps, highlights the potential of digital quantum processors for tackling previously intractable problems in theoretical physics. This work represents a step towards understanding the early universe and the physics of black holes through controlled quantum experiments. Light-cone curvature and frequency shifts characterise emergent spacetime in a deformed spin chain Following quenches from Néel and few-spin-flip states, observed light-cone propagation in the two-point correlation function |Czz ij (t)| revealed a clear deviation from linearity in the deformed XXZ chain. Specifically, the propagation speed varied with initial position, demonstrating the influence of the engineered spatial deformation. In the uniform chain, the correlation function exhibited a standard, linear light cone, as expected for ballistic propagation. Yet, in the deformed chain, the light cone visibly curved, conforming to the geodesics calculated from the effective metric, with Rindler horizons located at j∗+ 1 and N + 1 −j∗ where j∗= N/7. At a time of t=20 Trotter steps, the deformation induced a noticeable shift in the oscillation frequencies of the spin chain, directly reflecting the engineered spatial deformation and confirming that the qubits are experiencing a non-uniform effective spacetime. Unequal-time correlators, measured across the 80-qubit system, consistently showed ballistic quasiparticle propagation despite the strong spatial inhomogeneity, occurring at a speed determined by the local deformation profile, v(x). The research utilised superconducting transmon qubits on Heron processors to achieve this simulation, employing a first-order Suzuki-Trotter decomposition with a time step duration of δt. Each Trotter layer consisted of “odd” and “even” sublayers, composed of unitaries coupling nearest-neighbour qubits, with rotation gate angles θ = 2δtvj∆+π/2 and φ = −2δtvj −π/2. These parameters encode both local interactions through the anisotropy ∆ and emergent spacetime curvature through the deformation profile vj. The observed dynamical signatures remained visible for up to 20 Trotter steps, highlighting the system’s ability to simulate curved geometries with minimal error.

Simulating Curved Spacetime Dynamics via Programmable Superconducting Qubits Heron processors, comprising 80 superconducting qubits, underpinned the digital simulation of many-body dynamics in spatially curved backgrounds. These processors allowed for the precise engineering of spatially varying couplings within a spin-XXZ chain, a model chosen because its low-energy description closely resembles an inhomogeneous Tomonaga-Luttinger liquid. This careful construction enabled the realization of excitations that faithfully follow geodesic paths of an effective metric, directly mirroring the spatial deformation imposed on the system. Researchers induced dynamics by applying quenches, sudden changes, from both Néel and few-spin-flip initial states, allowing observation of emergent behaviour. At the heart of the methodology lies a decomposition of time evolution using the Trotter-Suzuki decomposition, a standard technique in quantum simulation that breaks down complex operations into a series of simpler, manageable steps. This approach, detailed in the supplementary material, allowed for the accurate propagation of the quantum state over extended timescales. The spin-XXZ chain was mapped onto the qubits using a specific arrangement of interactions, carefully calibrated to reproduce the desired spatial curvature. By controlling these interactions, the team effectively created a tunable, synthetic curved spacetime within the quantum processor. Maintaining coherence in such a complex system presented a significant challenge, addressed by leveraging advanced error mitigation techniques, as presented in the supplementary material. These techniques involved careful calibration of the qubits and the implementation of sophisticated pulse sequences. The choice of superconducting qubits was deliberate, offering a balance between coherence times and connectivity necessary for simulating these many-body systems. Beyond observing curved light-cone propagation and horizon-induced freezing, the team meticulously measured position-dependent oscillation frequencies, confirming that these frequencies were indeed governed by the engineered spatial deformation. Quantum simulation replicates spacetime geometry using superconducting qubits Scientists have long sought to model complex physical phenomena using increasingly sophisticated computational tools. A new demonstration using superconducting qubits brings a surprising connection to light: the ability to simulate aspects of curved spacetime within a quantum processor. While physicists have simulated relativistic effects before, this work distinguishes itself by creating a system where the propagation of quantum information genuinely reflects the geometry of a curved space, not merely its static properties. This isn’t about building wormholes; it’s about establishing a new level of control over quantum dynamics, mirroring behaviours seen in extreme astrophysical environments. Achieving this level of fidelity, demonstrating that quantum particles move as if on curved surfaces, has been a considerable challenge. Previous attempts often suffered from noise and limited qubit connectivity, hindering the observation of subtle relativistic effects.

This research showcases a system where excitations demonstrably follow geodesic paths, the shortest routes through the engineered spacetime, and where the emergence of horizon-like boundaries impacts quantum behaviour. The observed freezing of magnetization near these horizons provides a tangible link between quantum simulation and theoretical predictions. Interpreting these results requires careful consideration. The simulated spacetime is a highly artificial construct, built from the specific couplings between qubits. Extending this to more complex geometries or longer timescales remains a significant hurdle, as does scaling up the number of qubits while maintaining coherence. However, the fact that ballistic quasiparticle propagation was observed despite the strong spatial inhomogeneity is encouraging, suggesting a degree of robustness in the underlying physics. For the future, this work opens several avenues for exploration. Beyond refining the simulation of known spacetimes, researchers might investigate how quantum entanglement behaves in these synthetic gravitational fields, potentially informing our understanding of black hole information paradoxes. More immediately, this platform could become a testbed for new quantum algorithms, leveraging the unique properties of curved spacetime to enhance computational power. Once the limitations of qubit numbers and coherence are addressed, the possibilities for exploring fundamental physics, and perhaps even developing new technologies, become genuinely exciting. 👉 More information 🗞 Observing quantum many-body dynamics in emergent curved spacetime using programmable quantum processors 🧠 ArXiv: https://arxiv.org/abs/2602.15524 Tags: