Quantum Breakthrough: Large Systems Prove True Quantum Behavior
An international team of physicists has achieved a groundbreaking milestone by confirming that large quantum systems genuinely obey quantum mechanics. Using Bell's test across 73 qubits, researchers from Leiden University, Tsinghua University, and Zhejiang University demonstrated genuine quantum correlations that cannot be explained by classical physics. This research, published in October 2025, represents the largest-scale verification of quantum behavior ever conducted and provides critical validation for quantum computing technologies. The findings confirm that quantum computers are not merely scaling up in size but are becoming more authentically quantum, opening new possibilities for secure communication and advanced quantum algorithms.
In a landmark achievement for quantum physics, an international research team has definitively proven that large quantum systems truly operate according to the principles of quantum mechanics. This breakthrough, involving scientists from Leiden University, Tsinghua University in Beijing, and Zhejiang University in Hangzhou, represents the most comprehensive verification of quantum behavior at scale ever conducted.
The Quantum Lie Detector
The research team employed what they describe as a 'quantum lie detector' – Bell's test, originally designed by physicist John Bell. This test serves as a verification mechanism to determine whether quantum systems are genuinely utilizing quantum effects or merely simulating them. As quantum technologies continue to mature, increasingly rigorous validation methods become essential to ensure these systems operate as intended.
The study, detailed in research from the University of Leiden, marks a significant advancement in quantum verification. The team successfully tested Bell correlations in systems containing up to 73 qubits – the fundamental building blocks of quantum computers. This scale represents a substantial leap forward in quantum system validation.
Innovative Experimental Approach
Rather than attempting direct measurement of complex Bell correlations, the researchers adopted a clever strategy focusing on energy minimization – an area where quantum devices already demonstrate proficiency. This optimized approach proved remarkably successful, allowing the team to create specialized quantum states using 73 qubits in a superconducting quantum processor.
The experimental results revealed energy measurements far below what classical systems could achieve, with the difference measuring 48 standard deviations – making it statistically nearly impossible that the outcome resulted from chance. This dramatic deviation from classical expectations provides compelling evidence for genuine quantum behavior.
Beyond Basic Verification
The research team extended their investigation beyond standard Bell correlations to certify genuine multipartite Bell correlations – a more demanding form of quantum nonlocality requiring participation from all qubits in the system. This advanced verification demonstrates that quantum computers are not merely increasing in size but are improving in their ability to exhibit and prove authentic quantum behavior.
Remarkably, the researchers succeeded in preparing a series of low-energy states that passed this stringent test up to 24 qubits, efficiently confirming these specialized correlations. This achievement represents a significant milestone in quantum system characterization and validation.
Implications for Quantum Technology
This breakthrough has profound implications for the future of quantum computing and related technologies. The ability to certify deep quantum behavior in large, complex systems provides essential validation for quantum computer development. This verification ensures that quantum computers are truly operating according to quantum principles rather than merely simulating quantum behavior.
The insights gained from this research extend beyond theoretical interest. Understanding and controlling Bell correlations could lead to improvements in quantum communication systems, enhanced cryptographic security, and the development of novel quantum algorithms. As quantum technologies continue to evolve, this type of rigorous validation becomes increasingly critical for practical applications.
The successful demonstration of genuine quantum behavior at this scale represents a crucial step toward realizing the full potential of quantum computing. It confirms that the path toward larger, more powerful quantum systems is not merely one of scaling but of maintaining and enhancing authentic quantum characteristics – a fundamental requirement for achieving quantum advantage in practical applications.
