A team of researchers at the Indian Institute of Science Education and Research in Pune has achieved a significant breakthrough in quantum computing by extending the time qubits can effectively encode information. This advancement has enabled quantum particles to carry useful information for longer periods, marking a dramatic departure from previously established limits in quantum mechanics.
For decades, physicists have grappled with understanding the boundary between the quantum realm and the macroscopic world. A critical milestone in this exploration was the 1985 formulation of a mathematical test by physicists Anthony Leggett and Anupam Garg. This test, designed to assess the quantum nature of objects based on their correlations over time, revealed a fundamental limit known as the temporal Tsirelson’s bound (TTB). Objects that scored high on this test were considered quantum, but it was believed that even these objects could not exceed the constraints imposed by the TTB.
In a groundbreaking study, Arijit Chatterjee and his colleagues have found a method to surpass the TTB using a simple three-qubit system. The researchers utilized a carbon-based molecule containing three qubits, employing the first qubit to influence the behavior of the second, termed the target qubit. The third qubit was then used to extract the properties of the target.
This innovative approach allowed the target qubit to defy the limitations set by the TTB. The team discovered a remarkably high level of violation, which had not been achievable before. The key to their success lay in utilizing a quantum superposition state, where the first qubit effectively controlled the target qubit by allowing it to simultaneously exhibit two seemingly contradictory behaviors.
Typically, qubits experience a phenomenon known as decoherence over time, leading to a gradual loss of their ability to encode information. However, by breaking the TTB, the target qubit demonstrated a remarkable resilience, maintaining its information encoding capability for five times longer than previously possible. This enhancement is invaluable in contexts requiring precise control of qubits, particularly in computational applications.
The implications of this research extend beyond quantum computing. H. S. Karthik, a team member at the University of Gdansk, noted that this method could significantly improve quantum metrology, which involves highly accurate sensing of electromagnetic fields. Furthermore, Le Luo from Sun Yat-Sen University in China highlighted that this study not only has clear potential for refining quantum computing protocols but also fundamentally broadens our understanding of quantum object behavior over time.
The substantial violation of the TTB underscores the profound quantum correlations present within the three-qubit system, suggesting a level of quantumness that is unattainable in classical systems. As researchers continue to explore the boundaries of the quantum world, this advancement represents a pivotal step in unlocking the full potential of quantum technologies.