Researchers at the University of Science and Technology of China (USTC), in collaboration with the National University of Singapore and the University of Southampton, report demonstrating a quantum computational advantage using a processor built from ultracold atoms, rather than silicon. The team successfully sampled the driven thermalized states of a Bose-Hubbard system involving up to 64 sites with 20 atoms, achieving a Hilbert space dimension that surpasses the capabilities of current supercomputers by three orders of magnitude in terms of sampling rate. This work demonstrates the sampling of an interacting chaotic system performed on a quantum processor of ultracold atoms and opens the possibility of utilizing quantum computational advantage in simulating Floquet dynamics of many-body systems. Yong-Guang Zheng, Ying-Chao Shen, and Wei-Yong Zhang are listed as equal contributors to this research, signifying a highly collaborative effort within the USTC team.
Driven Bose-Hubbard System Sampling with Ultracold Atoms
A quantum processor leveraging ultracold atoms has demonstrated a computational advantage over the most powerful supercomputers in a specific task, marking a significant departure from silicon-based quantum computing platforms. The team’s approach centers on precise manipulation and atom-number-resolved detection using a quantum gas microscope with bichromatic superlattices. This allowed them to sample the driven Hubbard chains and two-leg ladders in a thermalized phase, a regime notoriously difficult for classical simulation due to the volume law scaling of Rényi entanglement entropy. The researchers explain in their published work that, owing to the intimate connection with a random matrix ensemble, it is proposed to be classically intractable to sample the driven thermalized many-body states of a Bose-Hubbard system and further extract multipoint correlations from the output strings for characterizing quantum systems. They employed Bayesian tests to verify the systems were indeed operating within the thermalized phase, confirming the validity of their results.
The significance of this achievement extends beyond simply exceeding the capabilities of existing supercomputers. The researchers were able to extract multipoint correlations of up to 14th-order from the experimental samples, providing clear distinctions between thermalized and many-body-localized phases.
Atom-Number-Resolved Detection via Quantum Gas Microscopy
The pursuit of scalable quantum computing has broadened the physical platforms under investigation, moving beyond superconducting circuits and trapped ions. This represents a departure from conventional silicon-based processors and highlights the growing internationalization of quantum research, with a Chinese institution taking a leading role. Central to this achievement is the implementation of a quantum gas microscope coupled with bichromatic superlattices, enabling precise manipulation. This technique allows researchers to not only manipulate individual atoms but also to precisely determine the number of atoms occupying each site within the optical lattice, a critical capability for verifying the system’s behavior. This level of control and measurement is essential for exploring complex quantum phenomena. The researchers rigorously tested the processor’s functionality, confirming that the atoms were behaving as predicted by theory; this verification is crucial, as achieving true quantum advantage requires demonstrating that the system is operating in a regime inaccessible to classical computation.
Rényi Entanglement Entropy and Thermal Phase Verification
Researchers at the University of Science and Technology of China (USTC) have demonstrated a step forward in quantum computational advantage, not through incremental improvements to silicon-based technology, but by leveraging a different platform: ultracold atoms. The team’s success hinges on their ability to accurately characterize the thermalized phase of a driven Bose-Hubbard system. Crucially, the researchers focused on rigorously verifying the system’s state, rather than simply achieving faster processing. They state, “We employ the Bayesian tests to verify that our prepared systems operate in the driven thermalized phase,” confirming the system’s behavior aligns with theoretical predictions. A key metric used to confirm this thermalization is the Rényi entanglement entropy, which scales in a way that means simulating the same system on a classical computer becomes exponentially more difficult as the system size increases.
Multipoint Correlations Distinguish Thermalized and Localized Phases
The ability to definitively distinguish between different phases of matter is crucial for developing new materials and technologies, and researchers are now applying this principle to quantum systems. A team led by Jian-Wei Pan of China (USTC) has demonstrated a method for differentiating between thermalized and many-body-localized phases using multipoint correlations extracted from a quantum processor built with ultracold atoms. This advancement isn’t simply about achieving higher computational power; it’s about gaining a deeper understanding of how complex quantum systems behave and verifying those behaviors with unprecedented precision. These high-order correlations proved to be the key to distinguishing between the thermalized and localized phases. While classical computational methods, such as tensor networks, struggle to accurately predict behavior in these complex systems, the ultracold atom processor provided clear distinctions. The observed “volume law scaling of the Rényi entanglement entropy in the thermalized phase” further confirmed the system’s behavior and its departure from simpler, classically simulatable models.
While much of the public conversation around quantum computing centers on the promise of universal, fault-tolerant machines, a more immediate path to practical quantum advantage is emerging through specialized devices. This wasn’t achieved with superconducting qubits or trapped ions, the dominant platforms attracting considerable investment, but with a quantum processor built from ultracold atoms. The team’s success hinges on the ability to precisely control and measure the behavior of these atoms within a carefully engineered optical lattice.
