Sign In

Communications of the ACM

ACM News

Cosmic Rays May Soon Stymie Quantum Computing


View as: Print Mobile App Share: Send by email Share on reddit Share on StumbleUpon Share on Hacker News Share on Tweeter Share on Facebook
A superconducting dark matter detector.

Natural radiation may interfere with both superconducting dark matter detectors and superconducting qubits.

Credit: Timothy Holland, PNNL

The practicality of quantum computing hangs on the integrity of the quantum bit, or qubit.

Qubits, the logic elements of quantum computers, are coherent two-level systems that represent quantum information. Each has the strange ability to be in a quantum superposition, carrying aspects of both states simultaneously, enabling a quantum version of parallel computation. Quantum computers, if they can be scaled to accommodate many qubits on one processor, could be dizzyingly faster, and able to handle far more complex problems, than today's conventional computers.

But that all depends on a qubit's integrity, or how long it can operate before its superposition and the quantum information are lost—a process called decoherence, which ultimately limits the computer run-time. Superconducting qubits—a leading qubit modality today—have achieved exponential improvement in this key metric, from less than one nanosecond in 1999 to around 200 microseconds today for the best-performing devices.

But researchers at MIT, MIT Lincoln Laboratory, and Pacific Northwest National Laboratory (PNNL) have found that a qubit's performance will soon hit a wall. In a paper published in Nature, the team reports that the low-level, otherwise harmless background that is emitted by trace elements in concrete walls and incoming cosmic rays are enough to cause decoherence in qubits. They found that this effect, if left unmitigated, will limit the performance of qubits to just a few milliseconds.

 

From Phys.org
View Full Article

 


 

No entries found