A strange new phase of matter created in a quantum computer behaves as if it has two time dimensions

A strange new phase of matter created in a quantum computer behaves as if it has two time dimensions

The Penrose tiling pattern is a type of semi-crystal, which means it has an ordered structure but never repeats. The pattern, made up of two shapes, is a two-dimensional projection of a square five-dimensional grid. credit: none

By shining a laser pulse sequence inspired by Fibonacci numbers into atoms inside a quantum computer, physicists have created a fascinating, never-before-seen phase of matter. The physicists reported on July 20 that the phase has benefits with two time dimensions even though there is still only one single flow of time. temper nature.

This mind-bending property offers a desirable benefit: the information stored in phase is more error-protected than the alternative settings currently used in quantum computers. As a result, information can exist without being distorted for longer, an important milestone for making quantum computing viable, says lead author of the study Filip Domitrescu.

Domitrescu, who worked on the project as a research fellow at the Center for Computational Quantum Physics in New York City, says that using the approach for an “extra time dimension” is an entirely different way of thinking about the phases of matter. “I’ve been working on these theoretical ideas for over five years, and seeing them actually come true in experiments is exciting.”

Domitrescu led the theoretical component of the study with Andrew Potter of the University of British Columbia in Vancouver, Roman Vasier of the University of Massachusetts, Amherst and Agish Kumar of the University of Texas at Austin. The experiments were performed on a quantum computer at Quantinuum in Broomfield, Colorado, by a team led by Brian Nienhuis.

The team’s quantum computer working units consist of 10 atomic ions of an element called ytterbium. Each ion is held and individually controlled by the electric fields produced by the ion trap, and can be manipulated or measured with laser pulses.

Each of these atomic ions function as scientists call quantum bits, or “qubits.” Whereas classical computers define information in bits (each representing a 0 or 1), the qubits used by quantum computers take advantage of the weirdness of quantum mechanics to store more information. Just like a dead and alive Schrödinger cat in its box, a qubit can be 0, 1 or a combination – or “overlay” – of both. The density of additional information and the way qubits interact with each other allow quantum computers to tackle computational problems beyond the reach of conventional computers.

However, there is a big problem: just as a peek into Schrödinger’s chest obscures the cat’s fate, so too does the interaction with the qubit. This interaction does not have to be intentional. “Even if you keep all of the atoms under tight control, they can lose their quantity by talking to their environment, heating up or interacting with things in ways they didn’t plan for,” Domitrescu says. “In practice, experimental devices contain many error sources that can degrade coherence after a few laser pulses.”

Thus, the challenge is to make qubits more powerful. To do this, physicists can use “symmetry,” which are essentially properties that withstand change. (A snowflake, for example, has rotational symmetry because it looks the same when rotated 60 degrees.) One way is to add temporal symmetry by blasting atoms with rhythmic laser pulses. This approach is useful, but Domitrescu and his collaborators wondered if they could move forward. So instead of just one-time symmetry, they aimed to add two using ordered but non-repetitive laser pulses.

A strange new phase of matter created in a quantum computer behaves as if it has two time dimensions

In this quantum computer, physicists have created an unprecedented phase of matter that functions as if time had two dimensions. The stage can help protect quantum information from destruction for much longer than current methods. Credit: Quantinum

The best way to understand their approach is to think of another ordered but not repetitive thing: “quasicrystals”. A typical crystal has a regular repeating structure, like hexagons in a honeycomb. The semi-crystal still has order, but its patterns are never repeated. (Penrose tiling is one example.) Even more surprisingly, semi-crystals are crystals of higher dimensions projected, or compressed, to lower dimensions. These higher dimensions can be further than the three dimensions of physical space: for example, a two-dimensional Penrose tiling is a projected slice of a five-dimensional lattice.

For qubits, Dumitrescu, Wasser and Potter proposed in 2018 to create a quasicrystal in time rather than space. While the periodic laser pulse may alternate (a, b, a, b, a, b, etc.), the researchers created a quasi-periodic laser pulse system based on the Fibonacci sequence. In such a sequence, each part of the sequence is the sum of the previous two parts (A, AB, ABA, ABAAB, ABAABABA, etc.). This arrangement, just like a semi-crystal, is arranged without repetition. A quasicrystal, it is a two-dimensional pattern compressed into one dimension. Flattening the dimensions theoretically results in two time symmetries instead of just one: the system essentially gets additional symmetry from an extra temporal dimension that does not exist.

However, actual quantum computers are incredibly complex experimental systems, so whether or not the benefits promised by theory will persist in real-world qubits has yet to be proven.

Using a quantum computer, experimentalists put the theory to the test. They pulsed laser light onto computer qubits periodically using a sequence based on Fibonacci numbers. The focus was on qubits at either end of the 10-atom configuration; This is where the researchers expected to see the new phase of matter simultaneously experiencing time symmetry. In the periodic test, the edge qubits remained quantum for about 1.5 seconds – a really staggering length given that the qubits were interacting strongly with each other. Using the quasi-periodic mode, the qubits remained quantum for the duration of the experiment, about 5.5 seconds. That’s because the consistency of the extra time provided more protection, Domitrescu says.

“With this quasi-periodic sequence, there’s a complex evolution that eliminates all the bugs that live on the edge,” he says. “Because of that, the edge stays quantum mechanically coherent a lot, much longer than you’d expect.”

Although the results demonstrate that the new phase of matter can act as a long-term storage of quantum information, researchers still need to functionally integrate the phase with the computational aspect of quantum computing. “We have this straightforward and impressive app, but we need to find a way to link it to the accounts,” Domitrescu says. “This is an open problem that we are working on.”

Doubling of Cooper pairs to protect qubits in quantum computers from noise

more information:
Philip Domitrescu, The dynamic topological phase achieved in a quantum-trapped ion simulation, temper nature (2022). DOI: 10.1038/s41586-022-04853-4. www.nature.com/articles/s41586-022-04853-4

Provided by Simons . Foundation

the quote: Strange New Phase of Matter Created in Quantum Computer Works As If It Has Two Time Dimensions (2022, July 20) Retrieved on July 20, 2022 from https://phys.org/news/2022-07-strange-phase- quantum-dimensions. programming language

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