#GOOGLE QUANTUM ERROR CORRECTION CODE#

In fact, his error-correction code was a response to skepticism about the feasibility of implementing his factoring algorithm. Shor is also responsible for the theoretical result that put quantum computing on the map, an algorithm that would enable a quantum computer to factor large numbers exponentially faster than a conventional computer can. The first quantum error correction code was invented in 1994 by Peter Shor, now the Morss Professor of Applied Mathematics at MIT, with an office just down the hall from Harrow’s. “It seemed that to figure out what the error was you had to measure, and measurement destroys your quantum information.” “People thought that error correction was impossible in the ’90s,” Harrow explains. The key to quantum algorithm design is manipulating the quantum state of the qubits so that when the superposition collapses, the result is (with high probability) the solution to a problem.īut the need to preserve superposition makes error correction difficult. Once you perform a measurement on the qubits, however, the superposition collapses, and the qubits take on definite values. This is the reason for quantum computers’ potential advantages: A string of qubits in superposition could, in some sense, perform a huge number of computations in parallel. Like a bit in a conventional computer, a qubit can represent 1 or 0, but it can also inhabit a state known as “quantum superposition,” where it represents 1 and 0 simultaneously. “So going above that is one of the reasons we’re excited about this work.” “There were many, many different proposals, all of which seemed to get stuck at this square-root point,” says Aram Harrow, an assistant professor of physics at MIT, who led the research. And for reasonably sized quantum computers, that fraction can be arbitrarily large - although the larger it is, the more qubits the computer requires. In a paper they’re presenting at the Association for Computing Machinery’s Symposium on Theory of Computing in June, researchers from MIT, Google, the University of Sydney, and Cornell University present a new code that can correct errors afflicting - almost - a specified fraction of a computer’s qubits, not just the square root of their number.

So they could correct eight errors in a 64-qubit quantum computer, for instance, but not 10. But until now, codes that could make do with limited measurements could correct only a limited number of errors - one roughly equal to the square root of the total number of qubits. The ideal quantum error correction code would correct any errors in quantum data, and it would require measurement of only a few quantum bits, or qubits, at a time. Crucial to most designs for quantum computers is quantum error correction, which helps preserve the fragile quantum states on which quantum computation depends. Quantum computers are largely theoretical devices that could perform some computations exponentially faster than conventional computers can.

Google quantum error correction