Enhancing Quantum Computer Behavior with Schrödinger’s Cat

Qubits inspired by Schrödinger’s cat were able to withstand errors for unusually long periods in quantum computing experiments. This could make them a promising building block for more reliable quantum computers in the future.

Researchers have long believed that quantum computers can solve problems that traditional computers cannot, but so far there have been few demonstrations of such capabilities. This is because quantum computers tend to make errors during calculations, but it is technically difficult to build quantum computers powerful enough to correct their own errors.

Zaki Legtas Researchers and their colleagues at France’s Ecole Normale Supérieure in collaboration with quantum computing startups alice and bobhave created a quantum bit (qubit) that avoids a particularly common type of error for an unprecedentedly long time of 10 seconds.

They created qubits by trapping light in tiny holes on a chip filled with tiny circuits made of perfectly conducting, or “superconducting,” wire. The light oscillates back and forth within the hole in two different ways. But instead of making it vibrate in only one direction, the researchers created a quantum superposition similar to the one involving the cat in Erwin Schrödinger’s famous thought experiment by making it behave in both directions. Therefore, this type of qubit is called a “cat qubit.”

According to Leghtas, physicists have theorized for more than a decade that cat qubits should be particularly unlikely to make so-called bit-flip errors. This is the equivalent of a traditional computer’s digital 0s naturally becoming 1s, and vice versa. However, it is not easy to demonstrate that laboratory cat qubits are highly resistant to bit flips.

He said he and his colleagues had been detecting bit-flip errors in the cat qubit every few milliseconds for several years. However, it was recently discovered that many of these errors were actually caused by the way the cat qubit’s state was measured. By redesigning that process, they made a huge technological leap. Their cat qubit now allows him to function for 10 seconds without bit flipping. This is 10,000 times longer than past experiments.

Researchers have so far built only one cat qubit with this property, but building more cat qubits could certainly be a step toward useful quantum computers. There is. This means that computers built using cat qubits use more qubits instead of reserving some qubits for computation and using the rest to correct bit-flip errors in the computation qubits. This is because the bits can be used for calculations. Leghtas says these his Cat qubits have the potential to reduce the number of qubits needed for error correction by about 10 times compared to other qubit designs, including superconducting circuits. states.

christian andersen The researchers from Delft University of Technology in the Netherlands say that while 10 seconds between bit flips is a very long time for a qubit, it’s not the only qubit property that is important. There is a trade-off between making cat qubits more resilient to bit-flip errors and making them more susceptible to accidentally causing other kinds of errors. Future research will need to find the most practical way to address this, he
says.

“This is really great. It’s great progress, but there are also a lot of challenges,” Andersen said.