Operation of a silicon quantum processor unit cell above one kelvin

Area of Science:

• Quantum Computing
• Solid-State Physics
• Materials Science

Background:

• Scaling quantum computers is limited by heat generation and the cooling power of dilution refrigerators.
• Current solid-state qubit technologies face significant challenges in achieving large-scale qubit numbers.

Purpose of the Study:

• To demonstrate a scalable silicon quantum processor unit cell operating at higher temperatures.
• To enable the development of quantum computers with integrated classical control electronics.

Main Methods:

• Utilized a silicon quantum processor unit cell with two qubits confined to quantum dots.
• Isolated quantum dots from the electron reservoir for initialization and readout via electron tunneling.
• Employed electrically driven spin resonance for coherent qubit control in isotopically enriched silicon.

Main Results:

• Achieved single-qubit gate fidelities of 98.6% and a coherence time of 2 microseconds at 1.5 Kelvin.
• Demonstrated operation at low magnetic fields (0.1 tesla) with qubit energy below thermal energy.
• Showcased a unit cell compatible with error-correction architectures and scalable to millions of qubits.

Conclusions:

• The demonstrated silicon quantum processor unit cell is a core building block for scalable quantum computers.
• Operation at 1.5 Kelvin is feasible, suggesting potential use of simpler pumped 4He cooling systems.
• This advancement could enable the integration of classical control electronics with qubit arrays, overcoming major scaling hurdles.