Ramped measurement technique for robust high-fidelity spin qubit readout

Area of Science:

• Quantum Computing
• Solid-State Physics
• Nanotechnology

Background:

• Single-electron spin qubits are crucial for quantum computing.
• Current readout methods rely on spin-to-charge conversion, requiring high qubit energy relative to system temperature.
• This limits operational temperature range and measurement speed.

Purpose of the Study:

• To develop a novel initialization and measurement technique for single-electron spin qubits.
• To improve readout fidelity and enable operation at higher temperatures.
• To overcome limitations of traditional energy-selective readout methods.

Main Methods:

• Demonstrated a new technique using voltage ramps instead of static voltages for qubit initialization and measurement.
• Utilized spin-to-charge conversion with a coupled charge sensor.
• Achieved state-to-charge readout fidelities above 99%.

Main Results:

• Achieved >99% state-to-charge readout fidelity.
• Required qubit energies approximately half of those needed for traditional methods.
• Enabled high-fidelity electron spin readout at higher operating temperatures.

Conclusions:

• The voltage ramp technique offers a significant advancement for single-electron spin qubit readout.
• This method allows for high-fidelity measurements at higher temperatures, expanding operational possibilities.
• The technique provides pragmatic benefits including dynamic feedback and simplified alignment.