The new quantum chip uses nine qubits — five “cat” qubits that are protected against bit-flip errors and four superconducting qubits to correct phase-flip errors. These elements are combined with five superconducting buffer circuits to ensure data processing stability. (Image credit: AWS)
Amazon Web Services (AWS) has unveiled a prototype quantum computing chip that is the world's first to feature error-proof “cat qubits” — the basic units of quantum computing information inspired by Schrödinger's famous cat thought experiment.
The quantum processing unit (QPU), called Ocelot, includes five data qubits, or cat qubits, to store information; five buffer circuits made of superconducting tantalum to stabilize the cat qubits; and four additional qubits to detect errors that occur during data processing.
These internal components are distributed across two integrated silicon microchips, each measuring about 0.16 square inches (1 square centimeter), making the device compact enough to fit on the tip of a finger.
The new architecture is designed to significantly reduce the cost and energy needed to correct errors that naturally occur in quantum systems. Scientists are still looking for solutions to this problem (some progress was made in a study conducted in February 2024, as well as in a study conducted in April of last year).
Notably, the researchers claim that the new technology could exponentially reduce the number of errors as more qubits are added to future versions of the chip. They presented their findings in a new study published Feb. 26 in the journal Nature.
Reducing quantum noise
Because qubits are inherently “noisy,” meaning they are susceptible to vibrations, heat, electromagnetic interference, and cosmic radiation, they are much more prone to failure than classical bits. The error rate of classical bits is 1 in 1 million million, while that of qubits is about 1 in 1,000. This significantly higher error rate often leads to quantum superposition collapse during computation and failure of quantum operations.
There are two types of errors: bit-flip errors, where the probability of measuring 0 becomes the probability of measuring 1; and phase-flip errors, where the qubit is rotated 180 degrees about its vertical axis. Bit-flip errors affect both bits and qubits, while phase-flip errors affect only qubits. The need to correct both types of errors in quantum systems is resource-intensive compared to error correction in classical computing.
For this reason, scientists argue that a quantum computer would need millions of qubits before it could even come close to achieving “quantum supremacy,” which would be impossible given the physical space, energy, and resources needed to build and run such a hypothetical machine. As a result, more and more research is focused on developing robust qubits integrated with error-correction technologies.
“Logical qubits,” which consist of multiple physical qubits that store the same information to distribute points of failure, are the most common method of error correction. However, AWS researchers argue that without further hardware improvements, current approaches are very expensive, as it takes thousands of physical qubits to form a single logical qubit with low error rates.
However, Ocelot uses a cat qubit design developed by French startup Alice & Bob. Named after Schrödinger’s famous cat thought experiment, this qubit is designed to be inherently resistant to bit-flip errors.
Using new “cat qubits”
Unlike conventional superconducting qubits used in systems developed by companies like IBM and Google, which can achieve a superposition of 1 and 0, cat qubits can achieve a double superposition of two quantum states at once. Scientists at Alice & Bob described how the technology works in a roadmap and white paper published in 2024.
Sourse: www.livescience.com
