The connection between quantum computers and time crystals is well-established. Before we discuss this further, let’s first review what these unique and intriguing crystals are. Theoretical physicists have been investigating them since 2012 when American physicist Frank Wilczek, a Nobel laureate in physics, proposed their formulation. Initially, the scientific community was skeptical, but Wilczek’s idea has gradually gained acceptance and followers.
Like any other crystal, the atoms in these structures are arranged uniformly and orderly, creating a repeating pattern. However, there’s a crucial difference between ordinary crystals and Wilczek's crystals. In ordinary crystals, the pattern repeats in space, while in time crystals, surprisingly, the pattern repeats in time.
It’s challenging to envision an object with this property, but there’s an even stranger aspect that we shouldn't overlook: Creating a crystal like those proposed by Wilczek requires finding a way to break temporal symmetry spontaneously. A stable object isolated from any disturbance remains unchanged over time, preserving time translation symmetry. However, a time crystal should maintain its stability while also periodically changing its crystal structure.
Time Crystals Can Do Quantum Computers a Big Favor
If we observed the time crystal at different points in time, we’d notice that its structure isn’t consistently the same. It should periodically change, a behavior that leads us to identify it as a new state of matter different from the solid, liquid, gas, and plasma phases. Under specific conditions, more unusual states of matter are also possible, such as the Bose-Einstein condensate, which is when extremely cold atoms move together as if they were a single atom. However, everyone’s more familiar with the four classic phases.
Researchers at the University of the Chinese Academy of Sciences have employed a time crystal to increase the stability of a quantum computer’s internal state.
Despite the exotic nature of these concepts, time crystals have already become a reality. A research group at Lancaster University in the UK, led by physicist Samuli Autti, successfully created the first one in 2022. Their time crystals are composed of magnons, which are spin-1 quasiparticles (rather than simply particles) capable of carrying energy and momentum in a crystal. Autti and his colleagues confirmed that the time crystals they created exhibit the same properties as those theoretically formulated by Wilczek.
Following the footsteps of Autti’s team, other research groups have also developed their own time crystals. One of these groups, from the University of the Chinese Academy of Sciences, has successfully enhanced the stability of the internal state of a quantum computer using a time crystal. The conditions that must be preserved to maintain the internal state of qubits are so demanding that these machines easily “forget” the information they’re working with.
This phenomenon is known as “quantum decoherence,” and when it appears, the quantum computer loses the advantage given by quantum effects and starts to behave like a traditional computer. The team of Chinese scientists led by Biao Huang has developed a method that has enabled them to use a time crystal to prolong the time span during which quantum entanglement between the qubits is maintained.
Scientists are fabricating a temporary circuit board in which they’re using ultracold potassium to create the time crystals.
However, this isn’t all. Two physicists from the Jagielloński University in Poland and another from the Swinburne University of Technology in Australia argue that time crystals can be used to minimize errors in quantum computers. In their paper, available as a pre-print on arXiv, they propose the use of a time circuit board that incorporates ultracold atoms exhibiting the same behavior as time crystals. According to their paper, this board allows the quantum computer’s qubits to interact without any degradation. Furthermore, the scientists also claim that by using it, distant qubits can interact in complex ways that are currently not possible.
This sounds great. Plus, if scientists can confirm that this technology is fully functional, quantum computers could be close. Scientists are currently creating a temporary circuit board where they use ultracold potassium to create time crystals. The experiment will definitively confirm whether their proposal really works. Let’s hope it does. It’d be one of the biggest milestones in quantum computing in recent years. Fingers crossed.
Image | IBM
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