Mit team cools trapped ions far below standard limit
Researchers from the Massachusetts Institute of Technology and MIT Lincoln Laboratory have developed a breakthrough technique that cools trapped ions to temperatures about 10 times lower than the conventional Doppler limit in laser cooling. This method, leveraging integrated photonics on a chip, achieves the feat in roughly 100 microseconds, outpacing existing approaches by several multiples. The innovation tackles a key bottleneck in trapped-ion quantum computing, where ions must approach absolute zero to curb vibrations that trigger computational errors.
Traditional setups rely on bulky external lasers and optics to target ions held in cryostats, limiting scalability to just dozens of qubits. The new polarization gradient cooling employs two light beams with differing polarizations that intersect to create a rotating vortex, efficiently damping ion motion. Implemented on a photonic chip with nanoscale antennas linked by waveguides, this allows envisioning thousands of sites on a single chip interfacing with numerous ions for scalable operations. Felix Knollmann, a doctoral student in MIT's physics department, noted that this paves the way for expansive quantum systems. The findings appear in Light: Science and Applications and Physical Review Letters.
In parallel, scientists from the Technical University of Vienna and Rice University reported observing an emergent topological semimetal, a quantum state once deemed impossible because it merges two supposedly incompatible phenomena. Working with a cerium-ruthenium-tin compound near absolute zero, they detected topological properties despite electrons lacking the precise velocities and energies typically required. Diana Kirschbaum, lead author from TU Wien, described the material as oscillating between states, rendering the quasiparticle concept meaningless in this fluctuating regime. Silke Bühler-Paschen, a TU Wien physics professor and co-leader, called it a major surprise, urging broader definitions of topological states. Theoretical modeling by Lei Chen in Qimiao Si's Rice group linked the behavior to quantum criticality itself. Published in Nature Physics, these advances promise practical quantum technologies, from scalable processors to advanced sensors and low-power electronics.
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