The study marks the first time researchers have captured the delicate process of spontaneous symmetry breaking in a quantum system precisely at zero temperature—an elusive regime where traditional experimental observations have long remained out of reach. By leveraging a state-of-the-art seven-qubit superconducting quantum processor, the team faithfully emulated the dynamics of a quantum many-body system undergoing a phase transition from a classical antiferromagnetic state to an entangled ferromagnetic quantum phase.

Initially, the system was arranged in a classical antiferromagnetic phase, where neighboring particles exhibit spin orientations that alternate sharply between two opposite directions, reflecting an ordered, staggered pattern with inherent symmetry. Through a carefully engineered digitized evolution, the quantum circuit guided the system to spontaneously reorganize itself into a ferromagnetic quantum phase, where all particle spins align uniformly while establishing intricate quantum correlations — a signature of entanglement.

According to Alan Santos, a physicist associated with the Institute of Fundamental Physics of the Spanish National Research Council and a key member of the theoretical team, the experiment reveals profound insights into quantum phase transitions driven by symmetry breaking. He elaborates, “The original spin configuration of alternating orientations evolved spontaneously into a uniformly aligned state—this transition is a direct consequence of the system breaking its initial symmetry as it reorganizes into a new phase.”

Spontaneous symmetry breaking lies at the heart of many critical phenomena in physics, from superconductivity to the Higgs mechanism, and serves as an essential mechanism enabling complex structures to emerge in nature. Yet, achieving a direct experimental handle on SSB at absolute zero—a state where thermal fluctuations vanish and quantum effects prevail exclusively—has remained one of the field’s most formidable challenges until now.

Absolute zero, defined as 0 Kelvin or -273.15 degrees Celsius, represents a theoretical limit where all classical motion ceases. While physically unattainable, simulating systems at this temperature theoretically strips away classical noise, isolating pure quantum mechanical behavior. The research team circumvented the impossibility of reaching absolute zero experimentally by instead digitally simulating the zero-temperature adiabatic evolution of their quantum spin lattice using a superconducting processor capable of exquisite control and measurement.

The quantum processor employed in the experiment featured seven superconducting qubits arranged in a linear lattice configuration that permitted only immediate neighbor interactions. This architecture closely mimicked the local interactions found in real quantum materials. By executing specialized algorithms that implement adiabatic evolution—a gradual ramping of system parameters to avoid excitations—the researchers ensured the system faithfully reproduced the zero-temperature ground state dynamics underlying symmetry breaking.

A critical aspect of detecting the phase transition involved analyzing quantum correlation functions and quantifying entanglement through Rényi entropy measures. Rényi entropy, a mathematical tool introduced by Hungarian mathematician Alfréd Rényi in the 1960s, provides a powerful metric to characterize the degree and distribution of quantum entanglement within a many-body system. The marked changes in these observables corroborated the onset of order and quantum coherence indicative of the ferromagnetic phase.

Entanglement, one of the most baffling yet fundamental features of quantum mechanics, describes correlations between particles so strong that the state of one instantaneously influences the state of another, regardless of spatial separation. “Superposition and entanglement are the dual pillars of quantum computation,” Santos explains. “While superposition allows a quantum system to explore multiple computational paths simultaneously, entanglement unlocks correlations that classical computers cannot replicate, vastly accelerating certain calculations.”

This quantum advantage was tangibly demonstrated through the simulation itself: what would be prohibitively complex for classical computers—tracking an evolving many-body quantum state with local interactions at zero temperature—became feasible within a manageable runtime on the superconducting quantum processor. The experiment thus validates the promise of quantum computing as a transformative tool to explore complex quantum phenomena that lie beyond classical reach.

The work was a collaborative triumph involving researchers from top institutions worldwide, including the Southern University of Science and Technology (SUSTech) in Shenzhen, China; Aarhus University in Denmark; and the Federal University of São Carlos (UFSCar) in Brazil. The actual physical implementation and execution of the quantum circuits took place at SUSTech, utilizing its cutting-edge superconducting quantum hardware cooled to near absolute zero temperatures—around one millikelvin—achieved through advanced dilution refrigerators.

Superconducting qubits, composed of aluminum and niobium alloys, offer strong advantages in scalability and coherence, a main reason why leading quantum computing efforts worldwide harness this technology. As Santos notes, “Building hundreds or even thousands of these qubits on a chip is technically feasible, providing a promising route toward practical, large-scale quantum processors essential for future quantum simulations and applications.”

Beyond the fundamental physics questions addressed, this experiment’s success underscores a broader paradigm shift ushered in by quantum computing: the capacity to simulate and understand quantum materials and phase transitions that have long eluded traditional approaches. Such capabilities could accelerate the discovery of novel quantum phases, materials, and technologies that harness quantum effects for computing, sensing, and communication.

Moreover, the research highlights how intertwining theoretical developments with state-of-the-art hardware implementations—in this case combining adiabatic algorithms with superconducting lattice processors—can yield unprecedented experimental insights into deep quantum phenomena. It eloquently embodies the symbiotic relationship between advancing quantum theory and enabling experimental quantum device engineering.

As physics continues to revolve around the profound interplay between symmetry and its breaking, this landmark study demonstrates that quantum computers are not merely abstract curiosities but potent new instruments to probe nature’s subtleties at the most fundamental level. The exploration of zero-temperature spontaneous symmetry breaking, once a purely theoretical concept, now takes a decisive step toward experimental reality—heralding a new age of quantum discovery.

Subject of Research: Quantum simulation of spontaneous symmetry breaking at zero temperature using superconducting qubits.

Article Title: Digital simulation of zero-temperature spontaneous symmetry breaking in a superconducting lattice processor

News Publication Date: 7-Apr-2025

Web References: https://doi.org/10.1038/s41467-025-57812-8

Image Credits: Alan Santos

Atomic nuclei are intricate quantum many-body systems composed of protons and neutrons bound by nuclear forces. The synthesis and study of rare and exotic isotopes open doors to unraveling aspects of nuclear structure and dynamics that remain largely unexplored. The nuclear chart theoretically encompasses around 7,000 nuclides, but experimental evidence exists for only about 3,300, leaving a significant domain uncharted. Creating neutron-deficient isotopes, especially in the heavy actinide region, is exceptionally challenging due to their fleeting existence and the minuscule likelihood of production, often quantified by extremely low cross-section values.

The newly synthesized isotope protactinium-210 lies deep within the proton drip line, an area of the nuclear chart where nuclei have so many protons relative to neutrons that they are prone to spontaneous proton emission or alpha decay. Producing such isotopes requires precision and innovation. At the China Accelerator Facility for Superheavy Elements (CAFE2), researchers accelerated a calcium-40 ion beam to bombard a lutetium-175 target. The resulting fusion-evaporation reaction led to the creation of protactinium-210 nuclei. Despite the extremely low production cross-section of approximately seven picobarns—equating to a probability of only a few events among trillions of reactions—researchers observed 23 distinct decay events, a testament to the facility’s sensitivity and the experiment’s meticulous design.

Central to the success was the use of the gas-filled recoil separator known as the Spectrometer for Heavy Atoms and Nuclear Structure-2 (SHANS2). This state-of-the-art instrument allows for efficient separation and identification of the desired heavy isotopes from a plethora of reaction byproducts. The detection of alpha decay signals enabled precise characterization of protactinium-210’s decay properties, extending existing systematics within this proton-rich region. The experimental results showed remarkable alignment with theoretical nuclear models, especially shell model calculations that predict nuclear behavior near and beyond the proton drip line, underscoring the robustness of modern nuclear theory.

Alpha decay, an essential mode of radioactive decay for heavy proton-rich nuclei, involves the emission of an alpha particle (two protons and two neutrons) from the parent nucleus, transforming it into a different element. Measuring the half-life and decay energies of protactinium-210 provides critical benchmarks for nuclear models and helps refine our understanding of nuclear forces under extreme proton-to-neutron ratios. The extremely short half-lives on the order of milliseconds to microseconds further highlight the experimental challenges faced by the team and the necessity for advanced detection and data acquisition systems.

The ramifications of synthesizing protactinium-210 extend beyond the identification of a new isotope. This milestone demonstrates the capability of CAFE2 to explore the landscape of heavy and superheavy nuclei, paving the way for future experiments aiming to discover new elements with even higher proton numbers. The delicate balance between nuclear binding energy and repulsive forces governs the limits of nuclear existence, and pushing these boundaries informs both nuclear physics and astrophysical phenomena such as nucleosynthesis in explosive stellar environments.

This research also reflects the continuous evolution and globalization of nuclear physics, with collaborative efforts crossing institutional and geographical boundaries. In addition to IMP, partners from the University of Chinese Academy of Sciences, Advanced Energy Science and Technology Guangdong Laboratory, Shandong University, and other contributing institutions played critical roles. Such joint ventures enhance the pooling of expertise, resources, and technologies necessary for high-stakes experimental undertakings.

Given the extraordinarily low production cross-sections and ephemeral existence of isotopes like protactinium-210, each observed decay event represents an invaluable data point. The statistical accumulation of 23 decay events was achieved through persistent experimentation and demonstrates the precision of experimental apparatus and methodology. This precision is vital for establishing reliable decay chains and confirms the isotope’s identity beyond reasonable doubt, distinguishing protactinium-210 from neighboring or contaminant nuclei.

From a broader perspective, studies of rare isotopes in the neutron-deficient actinide region yield insights into the nuclear shell effects and shape coexistence phenomena at the limits of nuclear stability. Such knowledge enriches theoretical frameworks and enhances predictive capabilities about nuclei far from stability, which are often inaccessible via other experimental means. This information is instrumental for applications ranging from nuclear medicine to understanding fundamental interaction forces within matter.

The fusion-evaporation technique employed here exemplifies the sophisticated experimental approaches required in modern nuclear synthesis. Accelerating medium-mass ion beams—such as calcium-40—and bombarding heavier targets can occasionally create compound nuclei that subsequently evaporate neutrons and protons to form new isotopes. Fine-tuning beam energies, target thicknesses, and detector sensitivities is essential for maximizing yields and isolating rare reaction channels that generate exotic isotopes like protactinium-210.

Looking ahead, the capability to synthesize and study such proton-rich isotopes suggests promising avenues for charting the unknown territories of the nuclear landscape. By extending alpha-decay systematics, researchers can validate nuclear models at extreme proton-to-neutron ratios, which has implications for understanding forces within the nucleus and predicting properties of yet-undiscovered elements. These explorations contribute fundamentally to our understanding of matter and the overarching principles that govern nuclear stability and transformation.

In summary, the landmark discovery of protactinium-210 represents a significant leap in nuclear science, achieved through advanced experimental ingenuity and international collaboration. It highlights the ongoing quest to map uncharted nuclides, challenges theoretical nuclear physics to account for extreme cases, and solidifies the prowess of cutting-edge research facilities like CAFE2. As humanity continues to probe the atomic nucleus, milestones such as these pave the way to unravel deeper cosmic and subatomic mysteries.

Subject of Research: Not applicable

Article Title: Discovery of the α-emitting isotope 210Pa

News Publication Date: 29-May-2025

Web References:
https://doi.org/10.1038/s41467-025-60047-2

References:
Nature Communications, DOI: 10.1038/s41467-025-60047-2, May 29, 2025.

Image Credits: IMP

Keywords

Particle physics, Nuclear physics, Particle accelerators, Particle theory

A groundbreaking development in this field has emerged from a collaborative research initiative spearheaded by a team from the Department of Physics at The University of Hong Kong (HKU). Their inventive approach, referred to as “entanglement microscopy,” presents a revolutionary means of probing the underlying structures of quantum entanglement. This method leverages advanced quantum Monte Carlo simulations to visualize and map entangled states at a microscopic scale. Through this innovative lens, researchers can dissect the subtle dynamics between entangled particles, dramatically enhancing our comprehension of quantum matter.

At the heart of the research is a focus on many-body quantum systems, where entanglement is inherently more complicated due to the exponential growth of degrees of freedom. The team, led by Professor Zi Yang MENG, and collaborated with researchers from the University of Montreal, aimed to unravel the intricacies of entanglement in two prominent models of two-dimensional systems: the transverse field Ising model and the fermionic t-V model. These models not only serve as fundamental benchmarks in quantum physics but also facilitate an in-depth exploration of entanglement behaviors and their implications for quantum state organization and interactions.

The implications of their findings are profound. The research unveiled critical distinctions in entanglement features dependent on the dimensionality of the system. For instance, in their examination of the Ising quantum critical point, they found that entanglement is predominantly short-range. Here, the interconnectedness of particles diminishes rapidly with increased distance, demonstrating a phenomenon termed “sudden death” where entangled relationships can abruptly vanish with minor temperature fluctuations or alterations in spatial separation. This behavior starkly contrasts with the observations made in the fermionic t-V model, which exhibited a more persistent entanglement despite greater separation among particles.

Another surprisingly intricate outcome highlighted by their investigations is the absence of three-party entanglement in two-dimensional Ising transitions, which stands in contrast to the presence of such entanglement in one-dimensional systems. This finding indicates that dimensionality plays a pivotal role in the structural formation of entangled particles. Such variations can be likened to social networks, where lower-dimensional systems correlate to small, tight-knit groups showcasing profound interconnections, while higher-dimensional systems reflect expansive networks that diminish intricate interactions.

Entanglement microscopy does not merely represent a theoretical advancement; it harbors practical applications that could redefine our technological landscape. As a consequence of this research, there exists potential to refine quantum computing methodologies, enhancing hardware applications and creating sophisticated algorithms suited for complex problem-solving in various fields, such as artificial intelligence and cryptography. Furthermore, this enhanced understanding of quantum entanglement may pave the way for groundbreaking advancements in next-generation quantum materials, which possess the ability to transform sectors including energy, electronics, and superconductivity.

Taking into account these profound implications, the study’s authors emphasize that these insights into entanglement structures could accelerate the progression of quantum simulations, thereby influencing research in adjoining disciplines such as chemistry and biology. This unearthing of fundamental physics could create a ripple effect, fostering ongoing innovations driven by the intricate understandings of entanglement derived from their studies.

In addition to its significance in pure research, the advancements showcased in this work are likely to attract the interest of diverse fields, from material science seeking to design innovative materials to computer scientists focused on expanding computational capabilities. The relevance of these findings transcends quantum physics, reaching into practical applications and cross-disciplinary collaborations that could alter the fabric of current technological paradigms.

As this research gains recognition and traction within the scientific community, it opens the door for further studies that could continue to unravel the complexities of quantum systems and enhance our understanding of the universe at a fundamental level. The marriage of entanglement studies with experimental approaches may accelerate the pace at which we explore these deep connections in quantum mechanics, eventually leading to previously unimagined breakthroughs.

In conjunction with these developments in quantum research, the significance of entangled states in our understanding of natural phenomena cannot be understated. Their intricate behaviors may shed light on the fundamental laws that govern the universe, shifting our perspective and potentially unlocking new scientific paradigms that challenge established theories. This essence of curiosity and exploration is essential in advancing our grasp of both the macroscopic and microscopic realms of reality.

The complete study detailing these findings has been formally published in the eminent journal Nature Communications. The rigorous examination and innovative methodologies presented in the paper offer a promising glance into the evolving landscape of quantum mechanics, spotlighting the relevance of entanglement in both theoretical insights and practical advancements.

By furthering our comprehension of quantum entanglement, the contributions made by this research team not only enrich academic discourse but also pave the way for future innovations. This unlocking of quantum entanglement’s secrets might significantly impact technology and scientific inquiry, drawing ever closer to elucidating the mysteries of the universe we inhabit.

In conclusion, the evolution of understanding around quantum entanglement and its implications continues to captivate researchers and technologists alike. As the exploration of entangled states throughout varying dimensions reveals subtleties not previously recognized, we edge closer to harnessing these phenomena in tangible applications that can potentially transform our world. With the promises showcased through entanglement microscopy, the quest for knowledge remains an exhilarating endeavor towards unraveling the intricacies of our universe.

Subject of Research: Quantum entanglement in many-body systems.
Article Title: Entanglement microscopy and tomography in many-body systems.
News Publication Date: 9-Dec-2024.
Web References: [Link to the publication if available]
References: [Citations of the study and relevant literature]
Image Credits: [Credits for any images used in the publication]

Keywords