Quantum computer creates particle that can remember its past

It may revolutionize how we approach quantum computing.
Loukia Papadopoulos
An illustration of quantum computing.jpg
An illustration of quantum computing.


A quantum computer has produced a particle, called an anyon, that can remember its past and improve quantum computing.

This is according to a report by New Scientist published on Tuesday.

The anyon is unique because it keeps a kind of record of where it has been. It was first discovered in the 1970s to exist in only two dimensions and resemble quasiparticles, collective vibrations that behave as if they are particles.

Swapping anyons keep a record of the number of swaps that influence the way they vibrate, making them an attractive way to do quantum computing, but they had never before been found experimentally.

Now, Henrik Dryer at quantum computing firm Quantinuum and his colleagues have developed a new quantum processor called H2, which can create qubits or quantum bits, the basic building block of a quantum computer and surface anyons.

A Kagome lattice

They did this by entangling these qubits in a formation called a Kagome lattice, a pattern of interlocking stars common in traditional woven Japanese baskets, giving them identical quantum mechanical properties to those predicted for anyons.

“This is the first convincing test that’s been able to do that, so this would be the first case of what you would call non-Abelian topological order,” told New Scientist Steven Simon at the University of Oxford. 

The quantum computer also allows the researchers to play around with the anyons to better understand their exotic state of matter, he added.

However, some researchers claim that Quantinuum has not actually created non-Abelian anyons. They argue that the firm has instead merely simulated them.

“I know they’re very excited about their work and they should be excited, but it is still a simulation,” told New Scientist Jiannis Pachos at the University of Leeds, UK. 

But Dryer claims that the quasiparticle nature of anyons means that a simulation is identical to the real thing. 

“A counterintuitive property of these anyons is that they are not really physical, they don’t care what they’re made of,” told New Scientist Dryer. 

“They’re just about information and entanglement – so if you have any system that can create that kind of entanglement, you can create the same type of anyons.”

The work is published in Cornell University's arxiv database.

Study abstract:

Non-Abelian topological order (TO) is a coveted state of matter with remarkable properties, including quasiparticles that can remember the sequence in which they are exchanged. These anyonic excitations are promising building blocks of fault-tolerant quantum computers. However, despite extensive efforts, non-Abelian TO and its excitations have remained elusive, unlike the simpler quasiparticles or defects in Abelian TO. In this work, we present the first unambiguous realization of non-Abelian TO and demonstrate control of its anyons. Using an adaptive circuit on Quantinuum's H2 trapped-ion quantum processor, we create the ground state wavefunction of D4 TO on a kagome lattice of 27 qubits, with fidelity per site exceeding 98.4%. By creating and moving anyons along Borromean rings in spacetime, anyon interferometry detects an intrinsically non-Abelian braiding process. Furthermore, tunneling non-Abelions around a torus creates all 22 ground states, as well as an excited state with a single anyon -- a peculiar feature of non-Abelian TO. This work illustrates the counterintuitive nature of non-Abelions and enables their study in quantum devices.

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