Superconducting Qubits
Qubits built from superconducting circuits that must operate near absolute zero. Used by IBM, Google, and others; the most widely deployed quantum computing approach today.
Superconducting qubits are built from electrical circuits made of superconducting materials, typically aluminum or niobium, that must be cooled to around 15 millikelvin to function. At this temperature, electrical resistance disappears and quantum effects in the circuit become observable and controllable.
The qubit states are typically stored in the energy levels of a Josephson junction, a specific superconducting circuit element. Quantum gate operations are performed using microwave pulses precisely tuned to the qubit's resonant frequency.
Superconducting qubits are the most commercially mature qubit modality. IBM has deployed systems with 1,000+ qubits. Google's Willow chip, announced in December 2024, demonstrated below-threshold quantum error correction, the first experimental result where adding more physical qubits actually reduced the logical error rate. The technology benefits from decades of semiconductor manufacturing knowledge.
The key challenge for superconducting qubits is that every qubit must be individually fabricated and calibrated, which creates engineering complexity as systems scale. This is one reason some researchers believe neutral atom systems have a scalability advantage.
No major Colorado company is building superconducting qubits, though Maybell Quantum's ColdCloud service provides the dilution refrigerator infrastructure that superconducting systems require. The 15 mK operating temperature of superconducting systems is the origin of this publication's name.