https://doi.org/10.48550/arXiv.2406.12820
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 https://doi.org/10.48550/arXiv.2406.12820
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 https://doi.org/10.48550/arXiv.2406.12820
 https://doi.org/10.48550/arXiv.2406.12820

Fibonacci anyons

Quantum physics

With IBM Quantum, we braid non-abelian Fibonacci anyons in string-net condensates to realise fault-tolerant universal quantum computation.

Realizing string-net condensation: Fibonacci anyon braiding for universal gates and sampling chromatic polynomials

In press Nature Communications (2025)

Z. K. Minev, K. Najafi, S. Majumder, J. Wang, A. Stern, E. Kim, C. Jian, G. Zhu

The remarkable complexity of the vacuum state of a topologically-ordered many-body quantum system encodes the character and intricate braiding interactions of its emergent particles, the anyons.} Quintessential predictions exploiting this complexity use the Fibonacci string-net condensate (Fib-SNC) and its Fibonacci anyons to go beyond classical computing. Sampling the Fib-SNC wavefunction is expected to yield estimates of the chromatic polynomial of graph objects, a classical task that is provably hard. At the same time, exchanging anyons of Fib-SNC is expected to allow fault-tolerant universal quantum computation. Nevertheless, the physical realization of Fib-SNC and its anyons remains elusive. Here, we introduce a scalable dynamical string-net preparation (DSNP) approach, suitable even for near-term quantum processors, which dynamically prepares Fib-SNC and its anyons through reconfigurable graphs. Using a superconducting quantum processor, we couple the DSNP approach with composite error-mitigation on deep circuits to successfully create, measure, and braid anyons of Fib-SNC in a scalable manner. We certify the creation of anyons by measuring their `anyon charge', finding an average experimental accuracy of 94%. Furthermore, we validate that exchanging these anyons yields the { expected} golden ratio~ϕ with~98% average accuracy and~8% measurement uncertainty. Finally, we sample the Fib-SNC to estimate the chromatic polynomial at~ϕ+2 for {several} graphs. Our results establish the proof of principle for using Fib-SNC and its anyons for fault-tolerant universal quantum computation and {for aiming at} a classically-hard problem.

In press Nature Communications (2025)

Z. K. Minev, K. Najafi, S. Majumder, J. Wang, A. Stern, E. Kim, C. Jian, G. Zhu