By firing a Fibonacci laser pulse at atoms inside a quantum computer, physicists have created an entirely new, strange phase of matter that behaves as if it has two time dimensions.
a new phase of issueCreated by using lasers to rhythmically vibrate a string of 10 ytterbium ions, it allows scientists to store information in a more error-proof manner, paving the way for quantum. computers that can store information for a long time without deterioration. The researchers published their findings in an article published on July 20 in the journal Nature (opens in new tab).
Including a theoretical “extra” time dimension is “a completely different way of thinking about the phases of matter,” said lead author Philip Dumitrescu, a researcher at the Center for Computational Quantum Physics at the Flatiron Institute in New York. said in the statement. “I am working on them theory ideas for more than five years and it’s exciting to see them come to fruition in practice.”
Physicists didn’t plan to create a stage with a theoretical extra time dimension, and they didn’t look for a way to ensure better storage of quantum information. Instead, they were interested in creating a new phase of matter—a new form in which matter can exist outside of the standard solid, liquid, and other substances. gasplasma
They began building a new stage in quantum computer company Quantinuum’s H1 quantum processor, which consists of 10 ytterbium ions in a vacuum chamber precisely controlled by lasers in a device known as an ion trap.
Conventional computers use bits, or 0s and 1s, to form the basis of all calculations. Quantum computers are designed to use qubits, which can exist in either a 0 or a 1 state. But that’s where the similarities end. Thanks to the strange laws of the quantum world, qubits can exist in a combination or superposition of both 0 and 1 states until they are measured, after which they randomly collapse to 0 or 1.
This strange behavior is key to the power of quantum computing, as it allows qubits to connect with each other. quantum entanglementto process this Albert Einstein called “scary action from afar”. Entanglement binds two or more qubits together and combines their properties in such a way that any change in one particle causes a change in the other, even if they are separated by large distances. This allows quantum computers to perform multiple calculations simultaneously, increasing their processing power exponentially compared to classical devices.
But the development of quantum computers is being held back by a major flaw: Qubits simply don’t interact or entangle; because they cannot be perfectly isolated from the environment outside the quantum computer, they also interact with the external environment, causing them to lose their quantum properties and the information they carry in a process called decoherence.
“Even if you keep everything atoms Under close supervision, they can lose their ‘quantity’ by talking to their surroundings, becoming agitated or interacting with things in ways you didn’t plan for,” Dumitrescu said.
To overcome these pesky decoherence effects and create a new, stable phase, physicists looked at a special set of phases called topological phases. Quantum entanglement not only allows quantum devices to encode information on the single, static positions of qubits, but also weaves them into the dynamic motions and interactions of an entire material—the material’s entangled states in their own shape or topology. . This creates a “topological” qubit that encodes information in a multi-part form rather than a single part, greatly reducing the likelihood of a phase losing its information.
The main feature of the transition from one phase to another is the breaking of physical symmetries – the idea that the laws of physics are the same for an object at any point in time or space. As a liquid, the molecules in water obey the same physical laws at every point and in every direction in space. But if you cool water enough to turn it into ice, its molecules will arrange themselves, choosing regular points along the crystal structure or lattice. Suddenly, water molecules prefer to occupy points in space and leave other points empty; the spatial symmetry of water is spontaneously broken.
Creating a new topological phase in a quantum computer is also based on symmetry breaking, but with this new phase, the symmetry is broken in time, not space.
By periodically perturbing each ion in the chain with lasers, the physicists wanted to break the continuous time symmetry of the ions at rest and impose their own time symmetry — where the qubits stay the same at certain intervals — a rhythmic topological phase across the material.
But the experiment failed. Instead of creating a topological phase immune to decoherence effects, regular laser pulses amplified the extraneous noise in the system and destroyed it in less than 1.5 seconds after activation.
After re-examining the experiment, the researchers realized that in order to create a more stable topological phase, it was necessary to bind more than one symmetry to the ionic chain to reduce the possibility of mixing the system. To do this, they set out to find a pulse pattern that was simple and did not repeat regularly, but showed some sort of higher symmetry over time.
That got them going Fibonacci sequence, the next number in the sequence is created by adding the previous two. While a simple periodic laser pulse could alternate between two laser sources (A, B, A, B, A, B, etc.), their new pulse train instead moved by combining the previous two pulses (A, AB, ABA, ABAAB, ABAABABA and so on.).
This Fibonacci pulsation, like a quasi-crystal in space, created an ordered time symmetry that never repeats. And just like a quasicrystal, Fibonacci pulses compress a higher-dimensional pattern onto a lower-dimensional surface. In the case of a spatial quasicrystal such as a Penrose slab, a slice of a five-dimensional grid is projected onto a two-dimensional surface. Looking at the Fibonacci pulse pattern, we see two theoretical time symmetries arranged into one physical symmetry.
“The system gains bonus symmetry from an extra time dimension that is essentially non-existent,” the researchers said in a statement. The system appears to be a material that exists in a higher dimension with two dimensions of time – even if this is physically impossible in reality.
When the team tested it, the new quasi-periodic Fibonacci pulse created a topographic phase that protected the system from data loss for the entire 5.5 seconds of the test. Indeed, they formed a phase immune to decoherence for a longer time than the others.
“In this quasi-periodic sequence, there is a complex evolution that cancels out all the bugs that live on the outside,” Dumitrescu said. “Therefore, the edge remains quantum-mechanically consistent for much, much longer than you would expect.”
Although the physicists have achieved their goal, one hurdle remains in turning their phase into a useful tool for quantum programmers: integrating it with the computational side of quantum computing so that it can be accessed with calculations.
“We have this direct, compelling application, but we need to find a way to connect it to computing,” Dumitrescu said. “It’s an open problem that we’re working on.”
Originally published in Live Science.