Quantum Computer Simulates Particle Physics with 51 Qubits

Rohan Joshi and colleagues at Ludwig Maximilian University of Munich present the largest quantum simulation of string-breaking dynamics to date, utilising a $5 \times $4 lattice and $$51 qubits on a \texttt{Quantinuum System Model H2} quantum computer. The simulation, a collaboration between Ludwig Maximilian University of Munich, RIKEN Centre for Quantum Computing (RQC), and College of Science, offers the first experimental realisation of string breaking and the emergence of dynamical gauge fields in two dimensions. Implementing a tunable plaquette term enabled observation of genuine $2+$1D dynamics and the creation of electron-positron pairs. This work paves the way for flexible quantum simulators capable of modelling photon-like propagation in gauge theories. Quantum simulation reveals dynamical gauge fields and string breaking in two-plus-one dimensions Employing $$51 qubits, the quantum simulation surpasses all prior efforts, representing a $$1540 entangling gate increase over previous simulations of string-breaking dynamics. This achievement unlocks the ability to probe genuine two-plus-one-dimensional ($2+$1D) dynamics, previously inaccessible due to limitations in both classical computation and the need for a tunable ‘plaquette term’, a mathematical component enabling active behaviour. Classical computational methods, such as lattice quantum chromodynamics (LQCD), face significant challenges when simulating real-time dynamics, particularly at high energies, due to the exponential growth of computational resources required with increasing system size and simulation time. This quantum simulation circumvents some of these limitations by leveraging the principles of quantum mechanics to directly represent the underlying physics. Physicists at Quantinuum, led by Scott Aaronson and Kristan Temme, experimentally realised string breaking and the emergence of dynamical gauge fields, observing the annihilation of string segments and the production of electron-positron pairs; these phenomena were only apparent when the plaquette term was actively engaged. The observation of electron-positron pair creation is particularly noteworthy, as it demonstrates the simulation’s ability to model fundamental particle production processes. A $5 \times $4 matter-site lattice facilitated the observation of matter creation extending across the entire lattice plane, and the simulation achieved a two-qubit gate depth of $$28 per Trotter step. The Trotter decomposition is a crucial technique in quantum simulation, allowing complex time evolution operators to be approximated as a sequence of simpler, implementable quantum gates. While the $$51 qubit scale still limits the simulation of more complex, realistic scenarios, a substantial increase in qubit count is needed to approach practical applications. The current simulation provides a foundational proof-of-principle, but scaling to larger lattice sizes and more complex particle interactions will require significant advancements in quantum hardware and error mitigation techniques. Dynamical gauge fields emerged, with string segments annihilating and producing electron-positron pairs, demonstrating a pathway for simulating photon-like propagation within programmable quantum systems. This ability to simulate dynamical gauge fields is crucial for understanding the fundamental forces governing particle interactions. Experimental establishment of string breaking, a process where energetic strings fragment, highlighted the importance of the tunable ‘plaquette term’ in achieving genuine two-dimensional dynamics. Further research will focus on scaling up the simulation to encompass more complex interactions, given the limitations of current qubit counts, and exploring the potential for simulating more realistic physical systems. U Quantum Link Simulation of Dynamical String Breaking The physicists employed a U quantum link model, a specific method for representing fundamental forces on a quantum computer, to simulate interactions in two dimensions. This model discretises space and time onto a lattice, creating a grid where interactions between particles can be calculated; it’s akin to building with Lego bricks, where larger structures emerge from smaller, connected components. Unlike traditional lattice gauge theory formulations that rely on classical fields, the U quantum link model represents the gauge fields themselves as quantum degrees of freedom, allowing for a more natural and efficient implementation on a quantum computer. The U(1) symmetry employed in this simulation corresponds to the symmetry of quantum electrodynamics, the theory of light and matter interactions.

The team specifically introduced a ‘plaquette term’, a mathematical component that allows for active behaviour, similar to adding a hinge to a flat structure. This term represents the interaction between the gauge fields and is essential for capturing the dynamics of the system. Without this term, the simulation would be limited to one dimension. The largest reported quantum simulation of string-breaking dynamics used 51 qubits on a Quantinuum System Model H2 computer, employing a shallow circuit design with up to 1540 entangling gates. The shallow circuit design minimises the impact of qubit decoherence, a major source of error in quantum computations. Classical methods struggle with these complex, real-time simulations, making this approach particularly valuable for exploring high-energy physics. The computational cost of simulating quantum field theories classically scales exponentially with the size of the lattice and the simulation time, whereas quantum simulations offer the potential for polynomial scaling, albeit with the challenges of building and controlling large-scale quantum computers. Quantum simulation replicates string fragmentation and dynamical gauge fields Modelling the behaviour of fundamental particles demands ever more powerful computational tools, and this work offers a promising step towards modelling high-energy physics with quantum computers. String breaking, the fragmentation of energetic strings, and the emergence of dynamical gauge fields have now been experimentally demonstrated, essential for understanding how forces operate between particles. This experiment represents the largest quantum simulation of its kind to date, utilising fifty-one qubits to model string breaking. The process of string breaking is crucial for understanding hadronization, the formation of hadrons (composite particles made of quarks and gluons) from the energetic strings produced in high-energy collisions. Understanding this fragmentation, known as hadronization, is vital for interpreting high-energy physics data. The quantum simulation successfully demonstrated string breaking and the emergence of dynamical gauge fields, fundamental components of particle physics, in two spatial dimensions, confirming matter creation extended across the entire lattice plane. Accurately modelling two-dimensional particle interactions remains significant, and this demonstration supports that goal. The ability to simulate these phenomena in a controlled quantum environment provides valuable insights into the underlying physics and could potentially lead to the development of new theoretical models. Future directions include exploring the effects of different lattice sizes, gauge groups, and particle interactions, as well as investigating the potential for using this simulation platform to study other fundamental problems in high-energy physics and condensed matter physics. The research successfully demonstrated string breaking and the emergence of dynamical gauge fields in a two-dimensional quantum simulation using fifty-one qubits. This is important because accurately modelling string fragmentation is crucial for understanding hadronization, the process by which particles are formed in high-energy collisions. The simulation revealed that signatures of genuine two-dimensional dynamics only appeared when a plaquette term was included, allowing for the propagation of photon-like excitations. Researchers intend to explore the effects of varying lattice sizes and particle interactions in future work. 👉 More information 🗞 Observation of genuine $2+1$D string dynamics in a U$(1)$ lattice gauge theory with a tunable plaquette term on a trapped-ion quantum computer 🧠 ArXiv: https://arxiv.org/abs/2604.07436 Tags: