surface code

Quantum's Problem Is Too Many Qubits, Not Too Few

Error correction works. That was settled this year. What nobody puts on a slide is the exchange rate: roughly a thousand fragile physical qubits to buy one reliable logical one, which lands a useful machine at millions of qubits against the few thousand that exist. A new family of codes published in Nature Communications claims to cut that ratio twenty-fold. Here is how, and the condition attached to it.