Quantum Error Correction
Research conducted by University of Massachusetts Amherst scientists has demonstrated “quantum dissipation engineering as a resource-efficient alternative or supplement to active quantum error correction (QEC) in future quantum computing architectures”, which in layman’s terms means the team are heading in the right direction to building a fault-tolerant quantum computer.
Published in the journal Nature, the paper, Protecting a bosonic qubit with autonomous quantum error correction, proves that QEC can be demonstrated, further breaking down some of the obstacles that have made a powerful quantum computer a possibility.
“What we just demonstrated was akin to painting the inside of the box in a special way and that somehow helps the cat better survive the inevitable harm of the outside world.”
— Chen Wang, a physicist at the University of Massachusetts Amherst
“Mid To Long Run”
The main obstacle to date has been from the quantum components themselves, which are fragile at best and react to any outside noise or interference, breaking down the quantum state of the qubits (quantum bits) in the system. To combat this problem, QEC is an indispensable component and key issue to preserving the delicate quantum information so important in QC.
“Although our experiment is still a rather rudimentary demonstration, we have finally fulfilled this counterintuitive theoretical possibility of dissipative QEC,” said co-author on the paper and physicist Chen Wang. “Looking forward, the implication is that there may be more avenues to protect our qubits from errors and do so less expensively. Therefore, this experiment raises the outlook of potentially building a useful fault-tolerant quantum computer in the mid to long run.”
So far, the team’s experiment has accomplished “passive QEC by tailoring the friction (or dissipation) experienced by the qubit”.
This can seem quite counterintuitive to those readers trained in physics amongst us, as ‘friction’ — which is in all sense and purposes external noise — is not regarded as conducive to quantum coherence, i.e. the building blocks of a reliable quantum computer.
Chen then alluded to German physicist Erwin Schrödinger’s famous thought experiment in relation to quantum coherence.
“Unfortunately, it is very difficult to keep a cat staying that way since any gas, light, or anything leaking into the box will destroy the magic: The cat will become either dead or just a regular live cat. The most straightforward strategy to protect a Schrodinger’s cat is to make the box as tight as possible, but that also makes it harder to use it for computation. What we just demonstrated was akin to painting the inside of the box in a special way and that somehow helps the cat better survive the inevitable harm of the outside world.”
It’s good to hear such stories of research in the quantum sphere, and although we’re still a long way to go in achieving the ultimate prize of a perfectly-built fault-tolerant quantum computer, Chen and his team’s work on spontaneous quantum error correction is certainly a move in the right direction.