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Error Fix For Long-Lived Qubits Brings Quantum Computers Nearer


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Artist's representation of quantum computing.

Yale University researchers have managed to store data in a quantum bit for 320 microseconds.

Credit: Mehau Kulyk/Science Photo Library

Researchers at Yale University have achieved a 20-fold increase in quantum bit (qubit) lifetime. The researchers were able to store the data for 320 microseconds, marking the first time quantum error correction (QEC) reached the "break-even" point, according to Yale professor Rob Schoelkopf.

The researchers built their QEC system to be as simple as possible, which reduces the chances of errors creeping in. Schoelkopf says the system consists of a superconductor inside an aluminum box, with a chamber on either side. One chamber is filled with microwave photons, which are linked to the superconductor, while the other is used to read from and write data to the superconducting qubit; the two chambers together encode a single quantum bit of information.

Schoelkopf says the system relies on the number of photons in the first chamber being even, so an error is introduced if one photon is lost, which happens naturally over time. The team uses quantum-state tomography to check the evenness or oddness of the photons.

The technique allows for a quick look at a quantum object without destroying it, and with continuous monitoring the researchers were able to count the number of errors and compensate for them when finally reading out the data from the superconducting qubit, according to Schoelkopf.

From New Scientist
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