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Photo: File

Tech News: Time crystals may change computing

By Louis Fourie Time of article published Aug 14, 2021

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During the month of July, Google Quantum AI, a joint initiative between Google, NASA and the non-profit Universities Space Research Association, and about 100 scientists from multiple universities all over the world, claimed to have used the Google sycamore quantum processor of 20 qubits (the sub-atomic particles that can represent both 1 and 0 and which are the foundation of quantum computing) to observe a genuine time crystal. It almost sounds like science fiction, since time crystals are pretty difficult to find.

Could Google’s harnessing of a time crystal inside their quantum computer really be “the most important scientific breakthrough of our lifetime” as some people are saying. I do not know if it is the breakthrough of our lifetime. But I do know that time crystals do not adhere to well-known scientific laws and that the achievement is therefore remarkable!

The second law of thermodynamics basically states that systems naturally tend to settle in a state of disorder, known as “maximum entropy”. This compelling drive toward change or thermal equilibrium, as described by the second law of thermodynamics, is the typical behaviour of all things that tend to move toward less useful, random states. As time passes, systems inexorably deteriorate into chaos and disorder or entropy.

Time crystals, however, do not play by the rules and do not settle in thermal equilibrium. They do not like change. Instead of slowly degenerating towards randomness, they become trapped in two high-energy configurations that they change between – a process that can continue forever. Time crystals are both stable and constantly in flux, with definable states being repeated at precise predictable intervals without ever regressing into a state of total randomness.

According to researchers this makes time crystals a special “phase of matter”, which has originally been theorised by Frank Wilczek in 2012 as a new state that could potentially join the ranks of solids, liquids and gases. He postulated that if the properties of matter change over time rather than in space that it might create new states of matter.

But what exactly is a time crystal? Time crystals are systems of atoms that organise themselves in time the way solids crystallise in space and represent a new phase of matter independent from the well-known solids, liquids and gasses that comprise our known universe.

A time crystal changes continually, but does not seem to use any energy. According to scientists this violates Isaac Newton’s first law of motion, which deals with inertia or the resistance an object has to change while in motion. Thus a rolling wheel will only stop when other forces act upon it or when friction forces it to ultimately stop. However, a time crystal will literally never stop.

Interestingly, time crystals act like superconducting materials (such as mercury or lead). Superconductivity is a typical quantum phenomenon where certain materials can conduct electricity without any energy loss if they are cooled below a certain temperature. They also expel magnetic fields.

Newtonian laws of physics revolve around symmetries. Before a liquid crystallises, the space it occupies is symmetric. If you sample the bottom, the top, or the middle of a cup of water, it would be exactly the same, thus occupying a symmetric space. But when the water crystallises, the atoms form rigid, set patterns. The space occupied by the crystal has become periodic and has broken spatial symmetry because of the repeating patterns in some directions rather than being the same in all directions.

Just as ordinary crystals are characterised by their repeating patterns in space, the continuous movement of time crystals exhibits repeating patterns in time or periodicity. As the periodicity of crystals breaks the symmetry of space, so does the periodicity of time crystals break the symmetry of time. Their atoms spin continually, changing directions as some pulsating force flips them. Quite literally, time crystals “tick” like a clock, and their atoms flip at a constant, periodic frequency.

But this is not the reason why they are called time crystals - the name comes from the fact that the crystals’ atomic structure repeats in time, which is why they seem to oscillate at set frequencies. Time crystals never find equilibrium the way that a diamond does.

Why is this so important? It is important since it means that time crystals can oscillate between forms without using any energy whatsoever. It could go on forever. This is of great importance in building a quantum computer, which is basically a quantum system far away from equilibrium.

Electronic computers, such as the trusted old laptops or desktop personal computers, are binary (1 or 0) and use logical gates that switch on and off. Quantum computers, however, work with qubits (quantum bits), which are often a single atom with a carefully controlled electron. Qubits involve many more possible states than just on and off. Although much more complex than traditional computers, quantum computers allow scientists to solve problems that involve more than just two binary outcomes.

This is where time crystals offer greater promise than quantum computing alone. Unlike unstable qubits, time crystals are stable and pulsate at constant intervals that might help scientists study certain repeating patterns or random numbers.

Although this research is still awaiting peer review for final publication it remains a remarkable breakthrough and historic. In their paper the scientists describe how they have built a special microscopic platform where a time crystal is surrounded by superconducting qubits (the basic unit of quantum information). Since the materials must be kept at an extremely low temperature for the advanced states like superconducting or time crystals, the quantum computer is situated inside a cryostat or a temperature-controlled supercooling chamber.

These special conditions allowed the scientists to achieve the first fully successful demonstration of a discrete time crystal in a quantum computer, which is no easy feat, since quantum computers are complex, difficult to build, maintain and use, and qubits are very unstable. When left alone the behaviour of qubits differ totally from when they are under observation. This instability makes it difficult to measure qubit states and complicates the use of quantum computers.

However, time crystals are very stable and defies Newtonian physics by constantly changing without using any energy. But not only did the scientists see a time crystal in action, but the process which produced it, is scalable. This makes the breakthrough even more meaningful and could potentially revolutionise the future of computing by trading unstable quantum bits for the stable time crystals as the essential building blocks in quantum computers. If independent scientists confirms the research, textbooks will probably be rewritten, and computing will be altered drastically. Time crystals will bring quantum coherence to a system where decoherence is a major challenge.

Our lives will also be changed since the next generation quantum computers may just solve the most complex problems on Earth with incredible speed and power that classical computers and humans have been unable to achieve such as developing a warp drive that would make interstellar travel possible and finding cures for currently incurable diseases.

Perhaps this discovery by Google is so big that we cannot fully comprehend it yet. At the current moment we can hardly understand time crystals that bends the laws of time and space!

Professor Louis CH Fourie is a technology strategist

*The views expressed here are not necessarily those of IOL or of title sites.


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