Rydberg Atom Arrays on Lieb Lattices Exhibit Quantum Liquid-Vapor Transition and Density

The quest to understand complex quantum systems receives a boost from new research into the behaviour of interacting particles, with implications for fields ranging from materials science to high-energy physics. Mark Hirsbrunner from the National Energy Research Scientific Computing Center, Milan Kornjača from QuEra Computing Inc., and Rhine Samajdar from Princeton University, alongside their colleagues, investigate this behaviour using a novel platform: arrays of Rydberg atoms arranged on a Lieb lattice. This work demonstrates a powerful ability to simulate quantum phenomena, revealing a range of ordered phases and a quantum analogue of a liquid-vapor transition, complete with observable hysteretic behaviour. Importantly, the team also observes unusually slow relaxation after sudden changes to the system, suggesting fundamental constraints on how these quantum systems reach equilibrium, and highlighting the potential of this platform to explore previously inaccessible quantum dynamics.

Neutral-atom quantum simulators represent a promising avenue for exploring strongly interacting many-body systems, with potential applications across condensed matter physics, statistical mechanics, and high-energy physics. Researchers are increasingly focused on these systems due to their ability to model complex quantum phenomena that are intractable for classical computers. This work combines quantum experiments, numerical calculations, and analytical methods to investigate the behaviour of these systems in detail, aiming to demonstrate a rich set of behaviours and advance the capabilities of neutral-atom quantum simulation as a tool for scientific discovery.

Lieb Lattice Rydberg Atom Array Characterization

This research centers on creating and studying quantum systems using Rydberg atoms arranged in a Lieb lattice, a structure with unique properties that allows for the exploration of exotic quantum phases and phenomena. The team aimed to map out the phase diagrams of these systems, identifying different quantum phases, symmetric, collinear, and star, and understanding the transitions between them. They combined experimental measurements using Rydberg atom arrays with numerical simulations, validating theoretical models and exploring system behaviour beyond the reach of either approach alone. The researchers successfully identified and characterized the symmetric, collinear, and star phases in their Rydberg atom arrays, demonstrating that the phase boundaries are sensitive to experimental conditions.

Experimental results consistently matched the predictions of the simulations, providing confidence in the accuracy of the models. They also observed evidence for a first-order quantum liquid-vapor transition, identifying a critical point and observing strong quantum fluctuations near it. A simple model successfully captured the qualitative features of this transition, including the critical point. Detailed analysis of the system revealed that the phase boundaries depend on how the edges of the system are defined. The team also developed an effective model that accurately describes the liquid-vapor transition, capturing the key features of the phase change.

This research demonstrates the versatility of the Rydberg atom array on a Lieb lattice as a platform for exploring a wide range of quantum phenomena, including exotic phases and quantum criticality, providing insights into strongly correlated quantum systems. Future research will focus on accurately determining the critical exponents associated with the phase transitions, requiring larger system sizes and more extensive simulations. Exploring the effects of quantum fluctuations beyond current theoretical approaches is also crucial for fully understanding the system’s behaviour. Investigating the impact of disorder on the phase diagrams and critical behaviour could reveal how robust these phases are, and further expand the capabilities of this platform.

Lieb Lattice Reveals Quantum Liquid-Vapor Transition

Researchers have demonstrated a powerful new platform for quantum simulation using neutral atoms arranged on a Lieb lattice, revealing complex quantum phenomena with unprecedented clarity. This work expands the capabilities of quantum simulators, allowing scientists to explore areas of physics previously inaccessible with conventional tabletop experiments. The team successfully mapped the ground states and phase diagram of the system, identifying various density-wave ordered phases, and achieved strong agreement between experimental observations and sophisticated theoretical simulations. A key breakthrough lies in the observation of a quantum analog of the classical liquid-vapor transition, a fundamental process in physics.

By carefully controlling the system with local detuning fields, researchers were able to induce a first-order phase transition between ordered phases, culminating in a quantum critical point. Detailed examination of this transition revealed hysteretic dynamics, providing insights into the underlying mechanisms driving the phase change. This level of control and observation represents a significant advancement in the ability to study phase transitions at the quantum level. Beyond static phases, the team investigated how the system responds to sudden changes, performing quantum quench experiments. These experiments revealed surprisingly slow relaxation dynamics following the quench, a phenomenon attributed to emergent kinetic constraints within the system. This slow relaxation is particularly noteworthy as it differs significantly from behaviour observed in simpler systems and presents a challenge for conventional simulations, highlighting the power of this new platform to access complex dynamics. The use of the Lieb lattice geometry proved crucial to these discoveries, enabling richer physics than that observed on more commonly studied lattice structures.

Lieb Lattice Reveals Slow Quantum Relaxation

This research demonstrates the versatility of neutral-atom quantum simulators by exploring a range of quantum phenomena using Rydberg atoms arranged on a Lieb lattice. The team successfully mapped the ground states and phase diagram of the system, identifying various density-wave ordered phases, and observed a quantum analog of a classical liquid-vapor transition, including its characteristic hysteretic dynamics. Furthermore, studies of quantum quenches revealed anomalously slow relaxation dynamics attributable to kinetic constraints within the system, highlighting the ability of these simulators to probe complex many-body quantum dynamics. These findings expand the capabilities of quantum simulation through advancements in lattice design, single-site control of local fields, and precise manipulation of boundary conditions.

While acknowledging the computational challenges inherent in simulating complex quantum systems, the authors suggest that the scalability of current Rydberg platforms offers the potential for more quantitative studies of these states and their associated quantum critical regimes. Future research directions include investigations into frustrated magnetism, glassy behaviour, and the emergence of dynamical gauge fields, as well as exploring the quantum analog of nucleation dynamics and hysteresis in quantum phase diagrams. The developed protocols offer a controlled environment for studying these phenomena and potentially addressing fundamental challenges in simulating nonequilibrium quantum systems.