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Research Highlights

Entangled quantum bits protected by symmetry

Shovan Dutta and Nigel Cooper

The researchers found a way to protect highly fragile quantum systems from noise, which could aid in the design and development of new quantum devices, such as ultrafast quantum computers.

Distant Bell pairs protected against noise in the middle

Entangled particle-hole pairs between left and right sides protected from noise at the centre by a hidden symmetry.

Dutta and Cooper showed that microscopic particles can remain inextricably linked, or entangled, over long distances even if there are random disruptions in the middle. This finding opens up a new window into the quantum world that can revolutionise future technology by preserving quantum effects in noisy environments.

Their study addresses one of the most counterintuitive predictions of quantum theory called "entanglement," where a measurement on one particle immediately affects another distant particle, no matter how far apart they are. Harnessing this peculiar feature, a quantum computer could perform calculations well beyond the capacities of even the most powerful supercomputers. However, entanglement is fragile and quickly suppressed by weak environmental noise, which is the single biggest hurdle for such aspirations.

The authors discover a simple setup in which one can prepare and stabilise entangled pairs of particles even in the presence of noise. They show the pairs are protected by a surprising “hidden” symmetry that allows one to control their number all the way from zero to a large maximum value. These conclusions apply to a broad class of physical systems and can be realised in existing experimental platforms.

Long-Range Coherence and Multiple Steady States in a Lossy Qubit Array S Dutta and NR Cooper, Phys. Rev. Lett. 125 240404 (2020)

Adapted from a Cambridge Research press release.

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