On December 9, 2024, Google Quantum AI Lab announced to the world “Willow,” a quantum chip capable of exponentially reducing quantum error as the number of qubits increases (see our article “Willow: Google’s new quantum chip” from 12/20/2024). The resonance of this announcement overshadowed other significant advances made by lesser-known players, which we would like to briefly review in this post.
Quantum error is the biggest challenge in building quantum chips, leading to experimentation with various solutions ranging from superconductors (very expensive) to trapped ions, from electron spin to diamonds, among others. On January 3, the Paris-based company Alice & Bob announced the creation of the “cat qubit” (named after the thought experiment known as “Schrödinger’s cat”), which is based on an antimony atom. Having eight quantum states instead of the classic two, it mitigates errors. Intuitively, this is simple to understand. The error consists of an unexpected (and therefore random) switch from state 0 to state 1 or vice versa. With the “Ailuro-Qubit” (forgive the neologism), seven consecutive errors are required (these quantum cats are less fortunate than real cats, having only seven lives!) to change the qubit’s microstate, drastically reducing the probability of error. But Alice & Bob’s ambition goes further, aiming to use Ailuro-Qubits to create logical qubits, which are collections of physical qubits that share the same information and must all be compromised simultaneously to cause a quantum error. This makes them more resilient because a compromised qubit can be identified and corrected by the others.
During the same days, Equal1, an Irish company with the mission of “democratizing” quantum computing, announced the creation of a quantum chip made from semiconductors with costs similar to traditional chips. This is possible because the spin (roughly, the rotation) of electrons is used as qubits, and silicon provides a stable environment for these quantum systems. More recently, Korean scientists have leveraged semiconductors to create 2D quantum chips (of course, 2D does not actually exist; the term is used here because they are as thin as a molecule), which are much less vulnerable to temperature fluctuations or stray electromagnetic waves, allowing them to maintain quantum coherence (essentially, information) for longer.
Just this month, at Chalmers University of Technology in Sweden, researchers managed to cool qubits down to 22 millikelvin (-273.13 degrees Celsius) using microwave radiation—an unprecedented temperature that allows quantum properties (such as entanglement) to be maintained, preventing errors for longer periods.
And on February 19, Microsoft announced Majorana 1, the most direct response to Google’s “Willow,” a prototype processor (QPU) currently capable of hosting eight qubits on new materials (indium arsenide and aluminum) that have never been used in this field before. These materials make the qubits much more reliable, resilient, and energy-efficient. We are talking about topological conductors based on the Majorana fermion, named after the mathematician who first theorized the coexistence of a subatomic particle and its antiparticle, enabling the capture of quantum information. These recent discoveries will allow the creation of QPUs with millions of qubits in years rather than decades, as previously expected.
All of this is a present that lays the foundation for future solutions. Meanwhile, we are also witnessing concrete advancements in Japan, where the 20-qubit trapped-ion quantum computer Reimei has been integrated with the Fugaku supercomputer (the sixth most powerful in the world). This supercomputer was chosen because its architecture allows ions to “move” (“ion shuttling”) within its circuits without altering their microstate (and thus the information they contain). We will not have quantum laptops or PCs replacing traditional ones anytime soon, but we can already solve some problems that traditional computers cannot handle. So why not support traditional computers in tackling these challenges? The key is enabling communication between bits and qubits, which is precisely what has been achieved in Japan.
Disclaimer: This article reflects the personal opinions of the contributors at Custodia Wealth Management who wrote it. It does not constitute investment advice, personalized consulting, or a recommendation, and it should not be considered as an invitation to engage in financial transactions.
