Discrete Time Crystals Achieve Robust Subharmonic Response with Power-Law Lifetime
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The pursuit of novel phases of matter extends beyond equilibrium systems, and recent attention focuses on discrete time crystals, materials exhibiting periodic behaviour driven by external stimuli. Ling-Zhi Tang from the Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area, alongside Xiao Li, Z. D. Wang, and Dan-Wei Zhang from South China Normal University, investigate a pathway to creating these time crystals without relying on disorder. Their work demonstrates that discrete time crystals emerge in a periodically kicked atomic spin chain, stabilised by a phenomenon called Floquet strong Hilbert space fragmentation, where the system’s quantum state breaks into many disconnected parts.
This research establishes a new mechanism for sustaining complex temporal order in quantum systems, revealing a robust and potentially scalable route towards creating and controlling these exotic phases of matter, and offering insights into non-equilibrium quantum dynamics. Many-Body Physics, Floquet Systems, and Simulation This compilation presents a comprehensive overview of research in many-body physics and quantum simulation, exploring the behavior of interacting quantum systems through theoretical developments, numerical methods, and experimental realizations. A significant focus lies on Floquet systems, which are periodically driven systems, and the associated concepts of prethermalization and the emergence of novel phases of matter. These studies investigate how these systems evolve and potentially reach stable, yet non-equilibrium, states. A central theme is Hilbert space fragmentation, a phenomenon where a quantum system’s state becomes confined to disconnected regions, leading to localization and suppressing thermal equilibrium. Researchers explore the conditions causing this fragmentation and its observable consequences, utilizing diverse experimental platforms for quantum simulation, including Rydberg atom arrays, trapped ions, superconducting qubits, and neutral atoms in optical lattices. Studies also address the effects of disorder on quantum systems, including Anderson localization, and explore topological phases of matter and their potential realization in quantum simulators. The research is categorized into theoretical foundations, investigations of Hilbert space fragmentation, and applications to specific quantum simulation platforms. Key theoretical papers establish the framework for understanding prethermalization and Floquet systems, while studies of fragmentation explore its origins and consequences. Investigations using Rydberg atom arrays demonstrate control over many-body dynamics and the realization of exotic magnetic states, and research with trapped ions and superconducting qubits showcases the simulation of topological phases and the exploration of non-equilibrium phenomena.
Floquet Model Creates Disorder-Free Discrete Time Crystals Scientists have demonstrated the creation of discrete time crystals, phases of matter exhibiting unique temporal order, using a periodically driven spin chain. This work introduces a Floquet model, a system evolving in discrete time steps, constructed from alternating Hamiltonian dynamics. The model utilizes a sequence of two distinct operations, a global spin flip and an interaction between spins, creating a system that does not require disorder for stabilization.
The team constructed the Floquet operator, defining the system’s evolution over a single period, and determined the corresponding effective Hamiltonian to characterize the system’s dynamics. They calculated the system’s energy levels and prepared initial states to observe spin-echo evolution under the Floquet operator. Detailed analysis of the system’s magnetization response, specifically the fidelity and autocorrelation functions, revealed a robust periodic oscillation, confirming the emergence of the time crystal order. The study demonstrates that strong interactions between spins promote Hilbert space fragmentation, a key mechanism for stabilizing the time crystal order in this disorder-free system.
Strong Fragmentation Sustains Discrete Time Crystals Researchers have demonstrated a novel mechanism for creating discrete time crystals within a periodically driven spin chain. This work establishes that strong Hilbert space fragmentation, where the system’s quantum state is confined to disconnected regions, can sustain these time crystals without the need for disorder. Numerical simulations reveal a period-doubling response, a hallmark of discrete time crystals, and uncover more complex, multi-periodic behavior arising from the interplay of different energy levels within the system. Analytical work proves the approximate conservation of magnetization and domain-wall number within the Floquet operator, consistent with numerical results detailing the structure of symmetry subspaces. The research establishes Floquet Hilbert space fragmentation as a viable, disorder-free mechanism for sustaining nontrivial temporal orders in out-of-equilibrium quantum many-body systems, offering a promising pathway for realizing these exotic phases on near-term quantum simulators. The findings highlight the potential of Hilbert space fragmentation for stabilizing and exploring novel quantum phases in disorder-free systems, opening new avenues for research in quantum materials and quantum information science.
Sustaining Discrete Time Crystals Without Disorder This research establishes a mechanism for sustaining discrete time crystals, phases of matter exhibiting periodic behavior in time, without relying on disorder. Scientists demonstrated the creation of these time crystals within a periodically driven spin chain, leveraging a phenomenon called Floquet Hilbert space fragmentation. This fragmentation creates a unique structure within the system that protects the time crystal order, allowing it to persist even in the absence of irregularities typically required for stabilization.
The team observed a robust subharmonic response, a key characteristic of discrete time crystals, and uncovered more complex, multi-periodic behavior arising from the interplay of different energy levels within the system. The lifetime of the time crystal order proved independent of the driving frequency and grew exponentially with the size of the system, confirming the effectiveness of the fragmentation in preserving the temporal order. Analytical work revealed the conservation of specific properties within the system, supporting the theoretical understanding of this fragmentation process. 👉 More information 🗞 Discrete time crystals enabled by Floquet strong Hilbert space fragmentation 🧠 ArXiv: https://arxiv.org/abs/2512.14182 Tags: